| Message ID | 20180628074253.21088-2-hverkuil@xs4all.nl (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jun 28, 2018 at 09:42:51AM +0200, Hans Verkuil wrote: > From: Hans Verkuil <hans.verkuil@cisco.com> > > This adds support for the DisplayPort CEC-Tunneling-over-AUX > feature that is part of the DisplayPort 1.3 standard. > > Unfortunately, not all DisplayPort/USB-C to HDMI adapters with a > chip that has this capability actually hook up the CEC pin, so > even though a CEC device is created, it may not actually work. > > Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> > --- > drivers/gpu/drm/Kconfig | 10 + > drivers/gpu/drm/Makefile | 1 + > drivers/gpu/drm/drm_dp_cec.c | 433 ++++++++++++++++++++++++++++++++ > drivers/gpu/drm/drm_dp_helper.c | 1 + > include/drm/drm_dp_helper.h | 56 +++++ > 5 files changed, 501 insertions(+) > create mode 100644 drivers/gpu/drm/drm_dp_cec.c > > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig > index 2a72d2feb76d..d5e217fd0c14 100644 > --- a/drivers/gpu/drm/Kconfig > +++ b/drivers/gpu/drm/Kconfig > @@ -122,6 +122,16 @@ config DRM_LOAD_EDID_FIRMWARE > default case is N. Details and instructions how to build your own > EDID data are given in Documentation/EDID/HOWTO.txt. > > +config DRM_DP_CEC > + bool "Enable DisplayPort CEC-Tunneling-over-AUX HDMI support" > + select CEC_CORE > + help > + Choose this option if you want to enable HDMI CEC support for > + DisplayPort/USB-C to HDMI adapters. > + > + Note: not all adapters support this feature, and even for those > + that do support this they often do not hook up the CEC pin. > + > config DRM_TTM > tristate > depends on DRM && MMU > diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile > index ef9f3dab287f..270266cc6eca 100644 > --- a/drivers/gpu/drm/Makefile > +++ b/drivers/gpu/drm/Makefile > @@ -41,6 +41,7 @@ drm_kms_helper-$(CONFIG_DRM_PANEL_BRIDGE) += bridge/panel.o > drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o > drm_kms_helper-$(CONFIG_DRM_KMS_CMA_HELPER) += drm_fb_cma_helper.o > drm_kms_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o > +drm_kms_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o > > obj-$(CONFIG_DRM_KMS_HELPER) += drm_kms_helper.o > obj-$(CONFIG_DRM_DEBUG_SELFTEST) += selftests/ > diff --git a/drivers/gpu/drm/drm_dp_cec.c b/drivers/gpu/drm/drm_dp_cec.c > new file mode 100644 > index 000000000000..1530ca685955 > --- /dev/null > +++ b/drivers/gpu/drm/drm_dp_cec.c > @@ -0,0 +1,433 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * DisplayPort CEC-Tunneling-over-AUX support > + * > + * Copyright 2018 Cisco Systems, Inc. and/or its affiliates. All rights reserved. > + */ > + > +#include <linux/kernel.h> > +#include <linux/module.h> > +#include <linux/slab.h> > +#include <drm/drm_dp_helper.h> > +#include <media/cec.h> > + > +/* > + * Unfortunately it turns out that we have a chicken-and-egg situation > + * here. Quite a few active (mini-)DP-to-HDMI or USB-C-to-HDMI adapters > + * have a converter chip that supports CEC-Tunneling-over-AUX (usually the > + * Parade PS176), but they do not wire up the CEC pin, thus making CEC > + * useless. > + * > + * Sadly there is no way for this driver to know this. What happens is > + * that a /dev/cecX device is created that is isolated and unable to see > + * any of the other CEC devices. Quite literally the CEC wire is cut > + * (or in this case, never connected in the first place). > + * > + * The reason so few adapters support this is that this tunneling protocol > + * was never supported by any OS. So there was no easy way of testing it, > + * and no incentive to correctly wire up the CEC pin. > + * > + * Hopefully by creating this driver it will be easier for vendors to > + * finally fix their adapters and test the CEC functionality. > + * > + * I keep a list of known working adapters here: > + * > + * https://hverkuil.home.xs4all.nl/cec-status.txt > + * > + * Please mail me (hverkuil@xs4all.nl) if you find an adapter that works > + * and is not yet listed there. > + * > + * Note that the current implementation does not support CEC over an MST hub. > + * As far as I can see there is no mechanism defined in the DisplayPort > + * standard to transport CEC interrupts over an MST device. It might be > + * possible to do this through polling, but I have not been able to get that > + * to work. > + */ > + > +/** > + * DOC: dp cec helpers > + * > + * These functions take care of supporting the CEC-Tunneling-over-AUX > + * feature of DisplayPort-to-HDMI adapters. > + */ > + > +/* > + * When the EDID is unset because the HPD went low, then the CEC DPCD registers > + * typically can no longer be read (true for a DP-to-HDMI adapter since it is > + * powered by the HPD). However, some displays toggle the HPD off and on for a > + * short period for one reason or another, and that would cause the CEC adapter > + * to be removed and added again, even though nothing else changed. > + * > + * This module parameter sets a delay in seconds before the CEC adapter is > + * actually unregistered. Only if the HPD does not return within that time will > + * the CEC adapter be unregistered. > + * > + * If it is set to a value >= NEVER_UNREG_DELAY, then the CEC adapter will never > + * be unregistered for as long as the connector remains registered. > + * > + * If it is set to 0, then the CEC adapter will be unregistered immediately as > + * soon as the HPD disappears. > + * > + * The default is one second to prevent short HPD glitches from unregistering > + * the CEC adapter. > + * > + * Note that for integrated HDMI branch devices that support CEC the DPCD > + * registers remain available even if the HPD goes low since it is not powered > + * by the HPD. In that case the CEC adapter will never be unregistered during > + * the life time of the connector. At least, this is the theory since I do not > + * have hardware with an integrated HDMI branch device that supports CEC. > + */ > +#define NEVER_UNREG_DELAY 1000 > +static unsigned int drm_dp_cec_unregister_delay = 1; > +module_param(drm_dp_cec_unregister_delay, uint, 0600); > +MODULE_PARM_DESC(drm_dp_cec_unregister_delay, > + "CEC unregister delay in seconds, 0: no delay, >= 1000: never unregister"); > + > +static int drm_dp_cec_adap_enable(struct cec_adapter *adap, bool enable) > +{ > + struct drm_dp_aux *aux = cec_get_drvdata(adap); > + u32 val = enable ? DP_CEC_TUNNELING_ENABLE : 0; > + ssize_t err = 0; > + > + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val); > + return (enable && err < 0) ? err : 0; > +} > + > +static int drm_dp_cec_adap_log_addr(struct cec_adapter *adap, u8 addr) > +{ > + struct drm_dp_aux *aux = cec_get_drvdata(adap); > + /* Bit 15 (logical address 15) should always be set */ > + u16 la_mask = 1 << CEC_LOG_ADDR_BROADCAST; > + u8 mask[2]; > + ssize_t err; > + > + if (addr != CEC_LOG_ADDR_INVALID) > + la_mask |= adap->log_addrs.log_addr_mask | (1 << addr); > + mask[0] = la_mask & 0xff; > + mask[1] = la_mask >> 8; > + err = drm_dp_dpcd_write(aux, DP_CEC_LOGICAL_ADDRESS_MASK, mask, 2); > + return (addr != CEC_LOG_ADDR_INVALID && err < 0) ? err : 0; > +} > + > +static int drm_dp_cec_adap_transmit(struct cec_adapter *adap, u8 attempts, > + u32 signal_free_time, struct cec_msg *msg) > +{ > + struct drm_dp_aux *aux = cec_get_drvdata(adap); > + unsigned int retries = min(5, attempts - 1); > + ssize_t err; > + > + err = drm_dp_dpcd_write(aux, DP_CEC_TX_MESSAGE_BUFFER, > + msg->msg, msg->len); > + if (err < 0) > + return err; > + > + err = drm_dp_dpcd_writeb(aux, DP_CEC_TX_MESSAGE_INFO, > + (msg->len - 1) | (retries << 4) | > + DP_CEC_TX_MESSAGE_SEND); > + return err < 0 ? err : 0; > +} > + > +static int drm_dp_cec_adap_monitor_all_enable(struct cec_adapter *adap, > + bool enable) > +{ > + struct drm_dp_aux *aux = cec_get_drvdata(adap); > + ssize_t err; > + u8 val; > + > + if (!(adap->capabilities & CEC_CAP_MONITOR_ALL)) > + return 0; > + > + err = drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CONTROL, &val); > + if (err >= 0) { > + if (enable) > + val |= DP_CEC_SNOOPING_ENABLE; > + else > + val &= ~DP_CEC_SNOOPING_ENABLE; > + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val); > + } > + return (enable && err < 0) ? err : 0; > +} > + > +static void drm_dp_cec_adap_status(struct cec_adapter *adap, > + struct seq_file *file) > +{ > + struct drm_dp_aux *aux = cec_get_drvdata(adap); > + struct drm_dp_desc desc; > + struct drm_dp_dpcd_ident *id = &desc.ident; > + > + if (drm_dp_read_desc(aux, &desc, true)) > + return; > + seq_printf(file, "OUI: %*pdH\n", > + (int)sizeof(id->oui), id->oui); > + seq_printf(file, "ID: %*pE\n", > + (int)strnlen(id->device_id, sizeof(id->device_id)), > + id->device_id); > + seq_printf(file, "HW Rev: %d.%d\n", id->hw_rev >> 4, id->hw_rev & 0xf); > + /* > + * Show this both in decimal and hex: at least one vendor > + * always reports this in hex. > + */ > + seq_printf(file, "FW/SW Rev: %d.%d (0x%02x.0x%02x)\n", > + id->sw_major_rev, id->sw_minor_rev, > + id->sw_major_rev, id->sw_minor_rev); > +} > + > +static const struct cec_adap_ops drm_dp_cec_adap_ops = { > + .adap_enable = drm_dp_cec_adap_enable, > + .adap_log_addr = drm_dp_cec_adap_log_addr, > + .adap_transmit = drm_dp_cec_adap_transmit, > + .adap_monitor_all_enable = drm_dp_cec_adap_monitor_all_enable, > + .adap_status = drm_dp_cec_adap_status, > +}; > + > +static int drm_dp_cec_received(struct drm_dp_aux *aux) > +{ > + struct cec_adapter *adap = aux->cec.adap; > + struct cec_msg msg; > + u8 rx_msg_info; > + ssize_t err; > + > + err = drm_dp_dpcd_readb(aux, DP_CEC_RX_MESSAGE_INFO, &rx_msg_info); > + if (err < 0) > + return err; > + > + if (!(rx_msg_info & DP_CEC_RX_MESSAGE_ENDED)) > + return 0; > + > + msg.len = (rx_msg_info & DP_CEC_RX_MESSAGE_LEN_MASK) + 1; > + err = drm_dp_dpcd_read(aux, DP_CEC_RX_MESSAGE_BUFFER, msg.msg, msg.len); > + if (err < 0) > + return err; > + > + cec_received_msg(adap, &msg); > + return 0; > +} > + > +static void drm_dp_cec_handle_irq(struct drm_dp_aux *aux) > +{ > + struct cec_adapter *adap = aux->cec.adap; > + u8 flags; > + > + if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, &flags) < 0) > + return; > + > + if (flags & DP_CEC_RX_MESSAGE_INFO_VALID) > + drm_dp_cec_received(aux); > + > + if (flags & DP_CEC_TX_MESSAGE_SENT) > + cec_transmit_attempt_done(adap, CEC_TX_STATUS_OK); > + else if (flags & DP_CEC_TX_LINE_ERROR) > + cec_transmit_attempt_done(adap, CEC_TX_STATUS_ERROR | > + CEC_TX_STATUS_MAX_RETRIES); > + else if (flags & > + (DP_CEC_TX_ADDRESS_NACK_ERROR | DP_CEC_TX_DATA_NACK_ERROR)) > + cec_transmit_attempt_done(adap, CEC_TX_STATUS_NACK | > + CEC_TX_STATUS_MAX_RETRIES); > + drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, flags); > +} > + > +/** > + * drm_dp_cec_irq() - handle CEC interrupt, if any > + * @aux: DisplayPort AUX channel > + * > + * Should be called when handling an IRQ_HPD request. If CEC-tunneling-over-AUX > + * is present, then it will check for a CEC_IRQ and handle it accordingly. > + */ > +void drm_dp_cec_irq(struct drm_dp_aux *aux) > +{ > + u8 cec_irq; > + int ret; > + > + mutex_lock(&aux->cec.lock); > + if (!aux->cec.adap) > + goto unlock; > + > + ret = drm_dp_dpcd_readb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1, > + &cec_irq); > + if (ret < 0 || !(cec_irq & DP_CEC_IRQ)) > + goto unlock; > + > + drm_dp_cec_handle_irq(aux); > + drm_dp_dpcd_writeb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1, DP_CEC_IRQ); > +unlock: > + mutex_unlock(&aux->cec.lock); > +} > +EXPORT_SYMBOL(drm_dp_cec_irq); > + > +static bool drm_dp_cec_cap(struct drm_dp_aux *aux, u8 *cec_cap) > +{ > + u8 cap = 0; > + > + if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CAPABILITY, &cap) != 1 || > + !(cap & DP_CEC_TUNNELING_CAPABLE)) > + return false; > + if (cec_cap) > + *cec_cap = cap; > + return true; > +} > + > +/* > + * Called if the HPD was low for more than drm_dp_cec_unregister_delay > + * seconds. This unregisters the CEC adapter. > + */ > +static void drm_dp_cec_unregister_work(struct work_struct *work) > +{ > + struct drm_dp_aux *aux = container_of(work, struct drm_dp_aux, > + cec.unregister_work.work); > + > + if (!aux->cec.adap) > + return; I guess this NULL check isn't particularly critical? > + mutex_lock(&aux->cec.lock); > + cec_unregister_adapter(aux->cec.adap); > + aux->cec.adap = NULL; > + mutex_unlock(&aux->cec.lock); > +} > + > +/* > + * A new EDID is set. If there is no CEC adapter, then create one. If > + * there was a CEC adapter, then check if the CEC adapter properties > + * were unchanged and just update the CEC physical address. Otherwise > + * unregister the old CEC adapter and create a new one. > + */ > +void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid) > +{ > + u32 cec_caps = CEC_CAP_DEFAULTS | CEC_CAP_NEEDS_HPD; > + unsigned int num_las = 1; > + u8 cap; > + > +#ifndef CONFIG_MEDIA_CEC_RC > + /* > + * CEC_CAP_RC is part of CEC_CAP_DEFAULTS, but it is stripped by > + * cec_allocate_adapter() if CONFIG_MEDIA_CEC_RC is undefined. > + * > + * Do this here as well to ensure the tests against cec_caps are > + * correct. > + */ > + cec_caps &= ~CEC_CAP_RC; > +#endif > + cancel_delayed_work_sync(&aux->cec.unregister_work); > + > + mutex_lock(&aux->cec.lock); > + if (!drm_dp_cec_cap(aux, &cap)) { > + /* CEC is not supported, unregister any existing adapter */ > + cec_unregister_adapter(aux->cec.adap); ... considering here we don't check for NULL. Also the check in the work is unlocked so I could imagine some slight race conditions if set_edid()/unset_edid() get called in a particularly funky way. But I suppose we shouldn't really do that so it's probably fine. And the cec_unregister_adapter() is done with the lock held anyway so any bogus pointers can't reach it. > + aux->cec.adap = NULL; > + goto unlock; > + } > + > + if (cap & DP_CEC_SNOOPING_CAPABLE) > + cec_caps |= CEC_CAP_MONITOR_ALL; > + if (cap & DP_CEC_MULTIPLE_LA_CAPABLE) > + num_las = CEC_MAX_LOG_ADDRS; > + > + if (aux->cec.adap) { > + if (aux->cec.adap->capabilities == cec_caps && > + aux->cec.adap->available_log_addrs == num_las) { > + /* Unchanged, so just set the phys addr */ > + cec_s_phys_addr_from_edid(aux->cec.adap, edid); > + goto unlock; > + } > + /* > + * The capabilities changed, so unregister the old > + * adapter first. > + */ > + cec_unregister_adapter(aux->cec.adap); > + } > + > + /* Create a new adapter */ > + aux->cec.adap = cec_allocate_adapter(&drm_dp_cec_adap_ops, > + aux, aux->cec.name, cec_caps, > + num_las); > + if (IS_ERR(aux->cec.adap)) { > + aux->cec.adap = NULL; > + goto unlock; > + } > + if (cec_register_adapter(aux->cec.adap, aux->cec.parent)) { > + cec_delete_adapter(aux->cec.adap); > + aux->cec.adap = NULL; > + } else { > + /* > + * Update the phys addr for the new CEC adapter. When called > + * from drm_dp_cec_register_connector() edid == NULL, so in > + * that case the phys addr is just invalidated. > + */ > + cec_s_phys_addr_from_edid(aux->cec.adap, edid); > + } > +unlock: > + mutex_unlock(&aux->cec.lock); > +} > +EXPORT_SYMBOL(drm_dp_cec_set_edid); > + > +/* > + * The EDID disappeared (likely because of the HPD going down). > + */ > +void drm_dp_cec_unset_edid(struct drm_dp_aux *aux) > +{ > + mutex_lock(&aux->cec.lock); > + if (!aux->cec.adap) > + goto unlock; > + cec_phys_addr_invalidate(aux->cec.adap); > + /* > + * We're done if we want to keep the CEC device > + * (drm_dp_cec_unregister_delay is >= NEVER_UNREG_DELAY) or if the > + * DPCD still indicates the CEC capability (expected for an integrated > + * HDMI branch device). > + */ > + if (drm_dp_cec_unregister_delay >= NEVER_UNREG_DELAY || > + drm_dp_cec_cap(aux, NULL)) > + goto unlock; > + > + mutex_unlock(&aux->cec.lock); > + cancel_delayed_work_sync(&aux->cec.unregister_work); > + mutex_lock(&aux->cec.lock); Can't we just do the cancel_work_sync() at the very start of the function? Either way this shouldn't deadlock anymore. For the series Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> > + > + if (aux->cec.adap) { > + /* > + * Unregister the CEC adapter after drm_dp_cec_unregister_delay > + * seconds. This to debounce short HPD off-and-on cycles from > + * displays. > + */ > + schedule_delayed_work(&aux->cec.unregister_work, > + drm_dp_cec_unregister_delay * HZ); > + } > +unlock: > + mutex_unlock(&aux->cec.lock); > +} > +EXPORT_SYMBOL(drm_dp_cec_unset_edid); > + > +/** > + * drm_dp_cec_register_connector() - register a new connector > + * @aux: DisplayPort AUX channel > + * @name: name of the CEC device > + * @parent: parent device > + * > + * A new connector was registered with associated CEC adapter name and > + * CEC adapter parent device. After registering the name and parent > + * drm_dp_cec_set_edid() is called to check if the connector supports > + * CEC and to register a CEC adapter if that is the case. > + */ > +void drm_dp_cec_register_connector(struct drm_dp_aux *aux, const char *name, > + struct device *parent) > +{ > + WARN_ON(aux->cec.adap); > + aux->cec.name = name; > + aux->cec.parent = parent; > + INIT_DELAYED_WORK(&aux->cec.unregister_work, drm_dp_cec_unregister_work); > + > + drm_dp_cec_set_edid(aux, NULL); > +} > +EXPORT_SYMBOL(drm_dp_cec_register_connector); > + > +/** > + * drm_dp_cec_unregister_connector() - unregister the CEC adapter, if any > + * @aux: DisplayPort AUX channel > + */ > +void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux) > +{ > + if (!aux->cec.adap) > + return; > + cancel_delayed_work_sync(&aux->cec.unregister_work); > + cec_unregister_adapter(aux->cec.adap); > + aux->cec.adap = NULL; > +} > +EXPORT_SYMBOL(drm_dp_cec_unregister_connector); > diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c > index a7ba602a43a8..f4a06b54aa7d 100644 > --- a/drivers/gpu/drm/drm_dp_helper.c > +++ b/drivers/gpu/drm/drm_dp_helper.c > @@ -1087,6 +1087,7 @@ static void drm_dp_aux_crc_work(struct work_struct *work) > void drm_dp_aux_init(struct drm_dp_aux *aux) > { > mutex_init(&aux->hw_mutex); > + mutex_init(&aux->cec.lock); > INIT_WORK(&aux->crc_work, drm_dp_aux_crc_work); > > aux->ddc.algo = &drm_dp_i2c_algo; > diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h > index c01564991a9f..d0a23db271dc 100644 > --- a/include/drm/drm_dp_helper.h > +++ b/include/drm/drm_dp_helper.h > @@ -1078,6 +1078,25 @@ struct drm_dp_aux_msg { > size_t size; > }; > > +struct cec_adapter; > +struct edid; > + > +/** > + * struct drm_dp_aux_cec - DisplayPort CEC-Tunneling-over-AUX > + * @lock: mutex protecting this struct > + * @adap: the CEC adapter for CEC-Tunneling-over-AUX support. > + * @name: name of the CEC adapter > + * @parent: parent device of the CEC adapter > + * @unregister_work: unregister the CEC adapter > + */ > +struct drm_dp_aux_cec { > + struct mutex lock; > + struct cec_adapter *adap; > + const char *name; > + struct device *parent; > + struct delayed_work unregister_work; > +}; > + > /** > * struct drm_dp_aux - DisplayPort AUX channel > * @name: user-visible name of this AUX channel and the I2C-over-AUX adapter > @@ -1136,6 +1155,10 @@ struct drm_dp_aux { > * @i2c_defer_count: Counts I2C DEFERs, used for DP validation. > */ > unsigned i2c_defer_count; > + /** > + * @cec: struct containing fields used for CEC-Tunneling-over-AUX. > + */ > + struct drm_dp_aux_cec cec; > }; > > ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, > @@ -1258,4 +1281,37 @@ drm_dp_has_quirk(const struct drm_dp_desc *desc, enum drm_dp_quirk quirk) > return desc->quirks & BIT(quirk); > } > > +#ifdef CONFIG_DRM_DP_CEC > +void drm_dp_cec_irq(struct drm_dp_aux *aux); > +void drm_dp_cec_register_connector(struct drm_dp_aux *aux, const char *name, > + struct device *parent); > +void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux); > +void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid); > +void drm_dp_cec_unset_edid(struct drm_dp_aux *aux); > +#else > +static inline void drm_dp_cec_irq(struct drm_dp_aux *aux) > +{ > +} > + > +static inline void drm_dp_cec_register_connector(struct drm_dp_aux *aux, > + const char *name, > + struct device *parent) > +{ > +} > + > +static inline void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux) > +{ > +} > + > +static inline void drm_dp_cec_set_edid(struct drm_dp_aux *aux, > + const struct edid *edid) > +{ > +} > + > +static inline void drm_dp_cec_unset_edid(struct drm_dp_aux *aux) > +{ > +} > + > +#endif > + > #endif /* _DRM_DP_HELPER_H_ */ > -- > 2.17.0
On 02/07/18 16:55, Ville Syrjälä wrote: > On Thu, Jun 28, 2018 at 09:42:51AM +0200, Hans Verkuil wrote: >> From: Hans Verkuil <hans.verkuil@cisco.com> >> >> This adds support for the DisplayPort CEC-Tunneling-over-AUX >> feature that is part of the DisplayPort 1.3 standard. >> >> Unfortunately, not all DisplayPort/USB-C to HDMI adapters with a >> chip that has this capability actually hook up the CEC pin, so >> even though a CEC device is created, it may not actually work. >> >> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> >> --- >> drivers/gpu/drm/Kconfig | 10 + >> drivers/gpu/drm/Makefile | 1 + >> drivers/gpu/drm/drm_dp_cec.c | 433 ++++++++++++++++++++++++++++++++ >> drivers/gpu/drm/drm_dp_helper.c | 1 + >> include/drm/drm_dp_helper.h | 56 +++++ >> 5 files changed, 501 insertions(+) >> create mode 100644 drivers/gpu/drm/drm_dp_cec.c >> >> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig >> index 2a72d2feb76d..d5e217fd0c14 100644 >> --- a/drivers/gpu/drm/Kconfig >> +++ b/drivers/gpu/drm/Kconfig >> @@ -122,6 +122,16 @@ config DRM_LOAD_EDID_FIRMWARE >> default case is N. Details and instructions how to build your own >> EDID data are given in Documentation/EDID/HOWTO.txt. >> >> +config DRM_DP_CEC >> + bool "Enable DisplayPort CEC-Tunneling-over-AUX HDMI support" >> + select CEC_CORE >> + help >> + Choose this option if you want to enable HDMI CEC support for >> + DisplayPort/USB-C to HDMI adapters. >> + >> + Note: not all adapters support this feature, and even for those >> + that do support this they often do not hook up the CEC pin. >> + >> config DRM_TTM >> tristate >> depends on DRM && MMU >> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile >> index ef9f3dab287f..270266cc6eca 100644 >> --- a/drivers/gpu/drm/Makefile >> +++ b/drivers/gpu/drm/Makefile >> @@ -41,6 +41,7 @@ drm_kms_helper-$(CONFIG_DRM_PANEL_BRIDGE) += bridge/panel.o >> drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o >> drm_kms_helper-$(CONFIG_DRM_KMS_CMA_HELPER) += drm_fb_cma_helper.o >> drm_kms_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o >> +drm_kms_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o >> >> obj-$(CONFIG_DRM_KMS_HELPER) += drm_kms_helper.o >> obj-$(CONFIG_DRM_DEBUG_SELFTEST) += selftests/ >> diff --git a/drivers/gpu/drm/drm_dp_cec.c b/drivers/gpu/drm/drm_dp_cec.c >> new file mode 100644 >> index 000000000000..1530ca685955 >> --- /dev/null >> +++ b/drivers/gpu/drm/drm_dp_cec.c >> @@ -0,0 +1,433 @@ >> +// SPDX-License-Identifier: GPL-2.0 >> +/* >> + * DisplayPort CEC-Tunneling-over-AUX support >> + * >> + * Copyright 2018 Cisco Systems, Inc. and/or its affiliates. All rights reserved. >> + */ >> + >> +#include <linux/kernel.h> >> +#include <linux/module.h> >> +#include <linux/slab.h> >> +#include <drm/drm_dp_helper.h> >> +#include <media/cec.h> >> + >> +/* >> + * Unfortunately it turns out that we have a chicken-and-egg situation >> + * here. Quite a few active (mini-)DP-to-HDMI or USB-C-to-HDMI adapters >> + * have a converter chip that supports CEC-Tunneling-over-AUX (usually the >> + * Parade PS176), but they do not wire up the CEC pin, thus making CEC >> + * useless. >> + * >> + * Sadly there is no way for this driver to know this. What happens is >> + * that a /dev/cecX device is created that is isolated and unable to see >> + * any of the other CEC devices. Quite literally the CEC wire is cut >> + * (or in this case, never connected in the first place). >> + * >> + * The reason so few adapters support this is that this tunneling protocol >> + * was never supported by any OS. So there was no easy way of testing it, >> + * and no incentive to correctly wire up the CEC pin. >> + * >> + * Hopefully by creating this driver it will be easier for vendors to >> + * finally fix their adapters and test the CEC functionality. >> + * >> + * I keep a list of known working adapters here: >> + * >> + * https://hverkuil.home.xs4all.nl/cec-status.txt >> + * >> + * Please mail me (hverkuil@xs4all.nl) if you find an adapter that works >> + * and is not yet listed there. >> + * >> + * Note that the current implementation does not support CEC over an MST hub. >> + * As far as I can see there is no mechanism defined in the DisplayPort >> + * standard to transport CEC interrupts over an MST device. It might be >> + * possible to do this through polling, but I have not been able to get that >> + * to work. >> + */ >> + >> +/** >> + * DOC: dp cec helpers >> + * >> + * These functions take care of supporting the CEC-Tunneling-over-AUX >> + * feature of DisplayPort-to-HDMI adapters. >> + */ >> + >> +/* >> + * When the EDID is unset because the HPD went low, then the CEC DPCD registers >> + * typically can no longer be read (true for a DP-to-HDMI adapter since it is >> + * powered by the HPD). However, some displays toggle the HPD off and on for a >> + * short period for one reason or another, and that would cause the CEC adapter >> + * to be removed and added again, even though nothing else changed. >> + * >> + * This module parameter sets a delay in seconds before the CEC adapter is >> + * actually unregistered. Only if the HPD does not return within that time will >> + * the CEC adapter be unregistered. >> + * >> + * If it is set to a value >= NEVER_UNREG_DELAY, then the CEC adapter will never >> + * be unregistered for as long as the connector remains registered. >> + * >> + * If it is set to 0, then the CEC adapter will be unregistered immediately as >> + * soon as the HPD disappears. >> + * >> + * The default is one second to prevent short HPD glitches from unregistering >> + * the CEC adapter. >> + * >> + * Note that for integrated HDMI branch devices that support CEC the DPCD >> + * registers remain available even if the HPD goes low since it is not powered >> + * by the HPD. In that case the CEC adapter will never be unregistered during >> + * the life time of the connector. At least, this is the theory since I do not >> + * have hardware with an integrated HDMI branch device that supports CEC. >> + */ >> +#define NEVER_UNREG_DELAY 1000 >> +static unsigned int drm_dp_cec_unregister_delay = 1; >> +module_param(drm_dp_cec_unregister_delay, uint, 0600); >> +MODULE_PARM_DESC(drm_dp_cec_unregister_delay, >> + "CEC unregister delay in seconds, 0: no delay, >= 1000: never unregister"); >> + >> +static int drm_dp_cec_adap_enable(struct cec_adapter *adap, bool enable) >> +{ >> + struct drm_dp_aux *aux = cec_get_drvdata(adap); >> + u32 val = enable ? DP_CEC_TUNNELING_ENABLE : 0; >> + ssize_t err = 0; >> + >> + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val); >> + return (enable && err < 0) ? err : 0; >> +} >> + >> +static int drm_dp_cec_adap_log_addr(struct cec_adapter *adap, u8 addr) >> +{ >> + struct drm_dp_aux *aux = cec_get_drvdata(adap); >> + /* Bit 15 (logical address 15) should always be set */ >> + u16 la_mask = 1 << CEC_LOG_ADDR_BROADCAST; >> + u8 mask[2]; >> + ssize_t err; >> + >> + if (addr != CEC_LOG_ADDR_INVALID) >> + la_mask |= adap->log_addrs.log_addr_mask | (1 << addr); >> + mask[0] = la_mask & 0xff; >> + mask[1] = la_mask >> 8; >> + err = drm_dp_dpcd_write(aux, DP_CEC_LOGICAL_ADDRESS_MASK, mask, 2); >> + return (addr != CEC_LOG_ADDR_INVALID && err < 0) ? err : 0; >> +} >> + >> +static int drm_dp_cec_adap_transmit(struct cec_adapter *adap, u8 attempts, >> + u32 signal_free_time, struct cec_msg *msg) >> +{ >> + struct drm_dp_aux *aux = cec_get_drvdata(adap); >> + unsigned int retries = min(5, attempts - 1); >> + ssize_t err; >> + >> + err = drm_dp_dpcd_write(aux, DP_CEC_TX_MESSAGE_BUFFER, >> + msg->msg, msg->len); >> + if (err < 0) >> + return err; >> + >> + err = drm_dp_dpcd_writeb(aux, DP_CEC_TX_MESSAGE_INFO, >> + (msg->len - 1) | (retries << 4) | >> + DP_CEC_TX_MESSAGE_SEND); >> + return err < 0 ? err : 0; >> +} >> + >> +static int drm_dp_cec_adap_monitor_all_enable(struct cec_adapter *adap, >> + bool enable) >> +{ >> + struct drm_dp_aux *aux = cec_get_drvdata(adap); >> + ssize_t err; >> + u8 val; >> + >> + if (!(adap->capabilities & CEC_CAP_MONITOR_ALL)) >> + return 0; >> + >> + err = drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CONTROL, &val); >> + if (err >= 0) { >> + if (enable) >> + val |= DP_CEC_SNOOPING_ENABLE; >> + else >> + val &= ~DP_CEC_SNOOPING_ENABLE; >> + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val); >> + } >> + return (enable && err < 0) ? err : 0; >> +} >> + >> +static void drm_dp_cec_adap_status(struct cec_adapter *adap, >> + struct seq_file *file) >> +{ >> + struct drm_dp_aux *aux = cec_get_drvdata(adap); >> + struct drm_dp_desc desc; >> + struct drm_dp_dpcd_ident *id = &desc.ident; >> + >> + if (drm_dp_read_desc(aux, &desc, true)) >> + return; >> + seq_printf(file, "OUI: %*pdH\n", >> + (int)sizeof(id->oui), id->oui); >> + seq_printf(file, "ID: %*pE\n", >> + (int)strnlen(id->device_id, sizeof(id->device_id)), >> + id->device_id); >> + seq_printf(file, "HW Rev: %d.%d\n", id->hw_rev >> 4, id->hw_rev & 0xf); >> + /* >> + * Show this both in decimal and hex: at least one vendor >> + * always reports this in hex. >> + */ >> + seq_printf(file, "FW/SW Rev: %d.%d (0x%02x.0x%02x)\n", >> + id->sw_major_rev, id->sw_minor_rev, >> + id->sw_major_rev, id->sw_minor_rev); >> +} >> + >> +static const struct cec_adap_ops drm_dp_cec_adap_ops = { >> + .adap_enable = drm_dp_cec_adap_enable, >> + .adap_log_addr = drm_dp_cec_adap_log_addr, >> + .adap_transmit = drm_dp_cec_adap_transmit, >> + .adap_monitor_all_enable = drm_dp_cec_adap_monitor_all_enable, >> + .adap_status = drm_dp_cec_adap_status, >> +}; >> + >> +static int drm_dp_cec_received(struct drm_dp_aux *aux) >> +{ >> + struct cec_adapter *adap = aux->cec.adap; >> + struct cec_msg msg; >> + u8 rx_msg_info; >> + ssize_t err; >> + >> + err = drm_dp_dpcd_readb(aux, DP_CEC_RX_MESSAGE_INFO, &rx_msg_info); >> + if (err < 0) >> + return err; >> + >> + if (!(rx_msg_info & DP_CEC_RX_MESSAGE_ENDED)) >> + return 0; >> + >> + msg.len = (rx_msg_info & DP_CEC_RX_MESSAGE_LEN_MASK) + 1; >> + err = drm_dp_dpcd_read(aux, DP_CEC_RX_MESSAGE_BUFFER, msg.msg, msg.len); >> + if (err < 0) >> + return err; >> + >> + cec_received_msg(adap, &msg); >> + return 0; >> +} >> + >> +static void drm_dp_cec_handle_irq(struct drm_dp_aux *aux) >> +{ >> + struct cec_adapter *adap = aux->cec.adap; >> + u8 flags; >> + >> + if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, &flags) < 0) >> + return; >> + >> + if (flags & DP_CEC_RX_MESSAGE_INFO_VALID) >> + drm_dp_cec_received(aux); >> + >> + if (flags & DP_CEC_TX_MESSAGE_SENT) >> + cec_transmit_attempt_done(adap, CEC_TX_STATUS_OK); >> + else if (flags & DP_CEC_TX_LINE_ERROR) >> + cec_transmit_attempt_done(adap, CEC_TX_STATUS_ERROR | >> + CEC_TX_STATUS_MAX_RETRIES); >> + else if (flags & >> + (DP_CEC_TX_ADDRESS_NACK_ERROR | DP_CEC_TX_DATA_NACK_ERROR)) >> + cec_transmit_attempt_done(adap, CEC_TX_STATUS_NACK | >> + CEC_TX_STATUS_MAX_RETRIES); >> + drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, flags); >> +} >> + >> +/** >> + * drm_dp_cec_irq() - handle CEC interrupt, if any >> + * @aux: DisplayPort AUX channel >> + * >> + * Should be called when handling an IRQ_HPD request. If CEC-tunneling-over-AUX >> + * is present, then it will check for a CEC_IRQ and handle it accordingly. >> + */ >> +void drm_dp_cec_irq(struct drm_dp_aux *aux) >> +{ >> + u8 cec_irq; >> + int ret; >> + >> + mutex_lock(&aux->cec.lock); >> + if (!aux->cec.adap) >> + goto unlock; >> + >> + ret = drm_dp_dpcd_readb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1, >> + &cec_irq); >> + if (ret < 0 || !(cec_irq & DP_CEC_IRQ)) >> + goto unlock; >> + >> + drm_dp_cec_handle_irq(aux); >> + drm_dp_dpcd_writeb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1, DP_CEC_IRQ); >> +unlock: >> + mutex_unlock(&aux->cec.lock); >> +} >> +EXPORT_SYMBOL(drm_dp_cec_irq); >> + >> +static bool drm_dp_cec_cap(struct drm_dp_aux *aux, u8 *cec_cap) >> +{ >> + u8 cap = 0; >> + >> + if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CAPABILITY, &cap) != 1 || >> + !(cap & DP_CEC_TUNNELING_CAPABLE)) >> + return false; >> + if (cec_cap) >> + *cec_cap = cap; >> + return true; >> +} >> + >> +/* >> + * Called if the HPD was low for more than drm_dp_cec_unregister_delay >> + * seconds. This unregisters the CEC adapter. >> + */ >> +static void drm_dp_cec_unregister_work(struct work_struct *work) >> +{ >> + struct drm_dp_aux *aux = container_of(work, struct drm_dp_aux, >> + cec.unregister_work.work); >> + >> + if (!aux->cec.adap) >> + return; > > I guess this NULL check isn't particularly critical? Correct. It can be removed since cec_unregister_adapter() also checks against NULL. > >> + mutex_lock(&aux->cec.lock); >> + cec_unregister_adapter(aux->cec.adap); >> + aux->cec.adap = NULL; >> + mutex_unlock(&aux->cec.lock); >> +} >> + >> +/* >> + * A new EDID is set. If there is no CEC adapter, then create one. If >> + * there was a CEC adapter, then check if the CEC adapter properties >> + * were unchanged and just update the CEC physical address. Otherwise >> + * unregister the old CEC adapter and create a new one. >> + */ >> +void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid) >> +{ >> + u32 cec_caps = CEC_CAP_DEFAULTS | CEC_CAP_NEEDS_HPD; >> + unsigned int num_las = 1; >> + u8 cap; >> + >> +#ifndef CONFIG_MEDIA_CEC_RC >> + /* >> + * CEC_CAP_RC is part of CEC_CAP_DEFAULTS, but it is stripped by >> + * cec_allocate_adapter() if CONFIG_MEDIA_CEC_RC is undefined. >> + * >> + * Do this here as well to ensure the tests against cec_caps are >> + * correct. >> + */ >> + cec_caps &= ~CEC_CAP_RC; >> +#endif >> + cancel_delayed_work_sync(&aux->cec.unregister_work); >> + >> + mutex_lock(&aux->cec.lock); >> + if (!drm_dp_cec_cap(aux, &cap)) { >> + /* CEC is not supported, unregister any existing adapter */ >> + cec_unregister_adapter(aux->cec.adap); > > ... considering here we don't check for NULL. > > Also the check in the work is unlocked so I could imagine some slight > race conditions if set_edid()/unset_edid() get called in a particularly > funky way. But I suppose we shouldn't really do that so it's probably > fine. And the cec_unregister_adapter() is done with the lock held anyway > so any bogus pointers can't reach it. Right. > >> + aux->cec.adap = NULL; >> + goto unlock; >> + } >> + >> + if (cap & DP_CEC_SNOOPING_CAPABLE) >> + cec_caps |= CEC_CAP_MONITOR_ALL; >> + if (cap & DP_CEC_MULTIPLE_LA_CAPABLE) >> + num_las = CEC_MAX_LOG_ADDRS; >> + >> + if (aux->cec.adap) { >> + if (aux->cec.adap->capabilities == cec_caps && >> + aux->cec.adap->available_log_addrs == num_las) { >> + /* Unchanged, so just set the phys addr */ >> + cec_s_phys_addr_from_edid(aux->cec.adap, edid); >> + goto unlock; >> + } >> + /* >> + * The capabilities changed, so unregister the old >> + * adapter first. >> + */ >> + cec_unregister_adapter(aux->cec.adap); >> + } >> + >> + /* Create a new adapter */ >> + aux->cec.adap = cec_allocate_adapter(&drm_dp_cec_adap_ops, >> + aux, aux->cec.name, cec_caps, >> + num_las); >> + if (IS_ERR(aux->cec.adap)) { >> + aux->cec.adap = NULL; >> + goto unlock; >> + } >> + if (cec_register_adapter(aux->cec.adap, aux->cec.parent)) { >> + cec_delete_adapter(aux->cec.adap); >> + aux->cec.adap = NULL; >> + } else { >> + /* >> + * Update the phys addr for the new CEC adapter. When called >> + * from drm_dp_cec_register_connector() edid == NULL, so in >> + * that case the phys addr is just invalidated. >> + */ >> + cec_s_phys_addr_from_edid(aux->cec.adap, edid); >> + } >> +unlock: >> + mutex_unlock(&aux->cec.lock); >> +} >> +EXPORT_SYMBOL(drm_dp_cec_set_edid); >> + >> +/* >> + * The EDID disappeared (likely because of the HPD going down). >> + */ >> +void drm_dp_cec_unset_edid(struct drm_dp_aux *aux) >> +{ >> + mutex_lock(&aux->cec.lock); >> + if (!aux->cec.adap) >> + goto unlock; >> + cec_phys_addr_invalidate(aux->cec.adap); >> + /* >> + * We're done if we want to keep the CEC device >> + * (drm_dp_cec_unregister_delay is >= NEVER_UNREG_DELAY) or if the >> + * DPCD still indicates the CEC capability (expected for an integrated >> + * HDMI branch device). >> + */ >> + if (drm_dp_cec_unregister_delay >= NEVER_UNREG_DELAY || >> + drm_dp_cec_cap(aux, NULL)) >> + goto unlock; >> + >> + mutex_unlock(&aux->cec.lock); >> + cancel_delayed_work_sync(&aux->cec.unregister_work); >> + mutex_lock(&aux->cec.lock); > > Can't we just do the cancel_work_sync() at the very start of the > function? Good point. That allows me to simplify this code a bit as well. > > Either way this shouldn't deadlock anymore. For the series > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> I'll post a v8, making these changes and adding your Reviewed-by. Thanks for your review! Hans > >> + >> + if (aux->cec.adap) { >> + /* >> + * Unregister the CEC adapter after drm_dp_cec_unregister_delay >> + * seconds. This to debounce short HPD off-and-on cycles from >> + * displays. >> + */ >> + schedule_delayed_work(&aux->cec.unregister_work, >> + drm_dp_cec_unregister_delay * HZ); >> + } >> +unlock: >> + mutex_unlock(&aux->cec.lock); >> +} >> +EXPORT_SYMBOL(drm_dp_cec_unset_edid); >> + >> +/** >> + * drm_dp_cec_register_connector() - register a new connector >> + * @aux: DisplayPort AUX channel >> + * @name: name of the CEC device >> + * @parent: parent device >> + * >> + * A new connector was registered with associated CEC adapter name and >> + * CEC adapter parent device. After registering the name and parent >> + * drm_dp_cec_set_edid() is called to check if the connector supports >> + * CEC and to register a CEC adapter if that is the case. >> + */ >> +void drm_dp_cec_register_connector(struct drm_dp_aux *aux, const char *name, >> + struct device *parent) >> +{ >> + WARN_ON(aux->cec.adap); >> + aux->cec.name = name; >> + aux->cec.parent = parent; >> + INIT_DELAYED_WORK(&aux->cec.unregister_work, drm_dp_cec_unregister_work); >> + >> + drm_dp_cec_set_edid(aux, NULL); >> +} >> +EXPORT_SYMBOL(drm_dp_cec_register_connector); >> + >> +/** >> + * drm_dp_cec_unregister_connector() - unregister the CEC adapter, if any >> + * @aux: DisplayPort AUX channel >> + */ >> +void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux) >> +{ >> + if (!aux->cec.adap) >> + return; >> + cancel_delayed_work_sync(&aux->cec.unregister_work); >> + cec_unregister_adapter(aux->cec.adap); >> + aux->cec.adap = NULL; >> +} >> +EXPORT_SYMBOL(drm_dp_cec_unregister_connector); >> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c >> index a7ba602a43a8..f4a06b54aa7d 100644 >> --- a/drivers/gpu/drm/drm_dp_helper.c >> +++ b/drivers/gpu/drm/drm_dp_helper.c >> @@ -1087,6 +1087,7 @@ static void drm_dp_aux_crc_work(struct work_struct *work) >> void drm_dp_aux_init(struct drm_dp_aux *aux) >> { >> mutex_init(&aux->hw_mutex); >> + mutex_init(&aux->cec.lock); >> INIT_WORK(&aux->crc_work, drm_dp_aux_crc_work); >> >> aux->ddc.algo = &drm_dp_i2c_algo; >> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h >> index c01564991a9f..d0a23db271dc 100644 >> --- a/include/drm/drm_dp_helper.h >> +++ b/include/drm/drm_dp_helper.h >> @@ -1078,6 +1078,25 @@ struct drm_dp_aux_msg { >> size_t size; >> }; >> >> +struct cec_adapter; >> +struct edid; >> + >> +/** >> + * struct drm_dp_aux_cec - DisplayPort CEC-Tunneling-over-AUX >> + * @lock: mutex protecting this struct >> + * @adap: the CEC adapter for CEC-Tunneling-over-AUX support. >> + * @name: name of the CEC adapter >> + * @parent: parent device of the CEC adapter >> + * @unregister_work: unregister the CEC adapter >> + */ >> +struct drm_dp_aux_cec { >> + struct mutex lock; >> + struct cec_adapter *adap; >> + const char *name; >> + struct device *parent; >> + struct delayed_work unregister_work; >> +}; >> + >> /** >> * struct drm_dp_aux - DisplayPort AUX channel >> * @name: user-visible name of this AUX channel and the I2C-over-AUX adapter >> @@ -1136,6 +1155,10 @@ struct drm_dp_aux { >> * @i2c_defer_count: Counts I2C DEFERs, used for DP validation. >> */ >> unsigned i2c_defer_count; >> + /** >> + * @cec: struct containing fields used for CEC-Tunneling-over-AUX. >> + */ >> + struct drm_dp_aux_cec cec; >> }; >> >> ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, >> @@ -1258,4 +1281,37 @@ drm_dp_has_quirk(const struct drm_dp_desc *desc, enum drm_dp_quirk quirk) >> return desc->quirks & BIT(quirk); >> } >> >> +#ifdef CONFIG_DRM_DP_CEC >> +void drm_dp_cec_irq(struct drm_dp_aux *aux); >> +void drm_dp_cec_register_connector(struct drm_dp_aux *aux, const char *name, >> + struct device *parent); >> +void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux); >> +void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid); >> +void drm_dp_cec_unset_edid(struct drm_dp_aux *aux); >> +#else >> +static inline void drm_dp_cec_irq(struct drm_dp_aux *aux) >> +{ >> +} >> + >> +static inline void drm_dp_cec_register_connector(struct drm_dp_aux *aux, >> + const char *name, >> + struct device *parent) >> +{ >> +} >> + >> +static inline void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux) >> +{ >> +} >> + >> +static inline void drm_dp_cec_set_edid(struct drm_dp_aux *aux, >> + const struct edid *edid) >> +{ >> +} >> + >> +static inline void drm_dp_cec_unset_edid(struct drm_dp_aux *aux) >> +{ >> +} >> + >> +#endif >> + >> #endif /* _DRM_DP_HELPER_H_ */ >> -- >> 2.17.0 >
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index 2a72d2feb76d..d5e217fd0c14 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -122,6 +122,16 @@ config DRM_LOAD_EDID_FIRMWARE default case is N. Details and instructions how to build your own EDID data are given in Documentation/EDID/HOWTO.txt. +config DRM_DP_CEC + bool "Enable DisplayPort CEC-Tunneling-over-AUX HDMI support" + select CEC_CORE + help + Choose this option if you want to enable HDMI CEC support for + DisplayPort/USB-C to HDMI adapters. + + Note: not all adapters support this feature, and even for those + that do support this they often do not hook up the CEC pin. + config DRM_TTM tristate depends on DRM && MMU diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index ef9f3dab287f..270266cc6eca 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -41,6 +41,7 @@ drm_kms_helper-$(CONFIG_DRM_PANEL_BRIDGE) += bridge/panel.o drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o drm_kms_helper-$(CONFIG_DRM_KMS_CMA_HELPER) += drm_fb_cma_helper.o drm_kms_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o +drm_kms_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o obj-$(CONFIG_DRM_KMS_HELPER) += drm_kms_helper.o obj-$(CONFIG_DRM_DEBUG_SELFTEST) += selftests/ diff --git a/drivers/gpu/drm/drm_dp_cec.c b/drivers/gpu/drm/drm_dp_cec.c new file mode 100644 index 000000000000..1530ca685955 --- /dev/null +++ b/drivers/gpu/drm/drm_dp_cec.c @@ -0,0 +1,433 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * DisplayPort CEC-Tunneling-over-AUX support + * + * Copyright 2018 Cisco Systems, Inc. and/or its affiliates. All rights reserved. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <drm/drm_dp_helper.h> +#include <media/cec.h> + +/* + * Unfortunately it turns out that we have a chicken-and-egg situation + * here. Quite a few active (mini-)DP-to-HDMI or USB-C-to-HDMI adapters + * have a converter chip that supports CEC-Tunneling-over-AUX (usually the + * Parade PS176), but they do not wire up the CEC pin, thus making CEC + * useless. + * + * Sadly there is no way for this driver to know this. What happens is + * that a /dev/cecX device is created that is isolated and unable to see + * any of the other CEC devices. Quite literally the CEC wire is cut + * (or in this case, never connected in the first place). + * + * The reason so few adapters support this is that this tunneling protocol + * was never supported by any OS. So there was no easy way of testing it, + * and no incentive to correctly wire up the CEC pin. + * + * Hopefully by creating this driver it will be easier for vendors to + * finally fix their adapters and test the CEC functionality. + * + * I keep a list of known working adapters here: + * + * https://hverkuil.home.xs4all.nl/cec-status.txt + * + * Please mail me (hverkuil@xs4all.nl) if you find an adapter that works + * and is not yet listed there. + * + * Note that the current implementation does not support CEC over an MST hub. + * As far as I can see there is no mechanism defined in the DisplayPort + * standard to transport CEC interrupts over an MST device. It might be + * possible to do this through polling, but I have not been able to get that + * to work. + */ + +/** + * DOC: dp cec helpers + * + * These functions take care of supporting the CEC-Tunneling-over-AUX + * feature of DisplayPort-to-HDMI adapters. + */ + +/* + * When the EDID is unset because the HPD went low, then the CEC DPCD registers + * typically can no longer be read (true for a DP-to-HDMI adapter since it is + * powered by the HPD). However, some displays toggle the HPD off and on for a + * short period for one reason or another, and that would cause the CEC adapter + * to be removed and added again, even though nothing else changed. + * + * This module parameter sets a delay in seconds before the CEC adapter is + * actually unregistered. Only if the HPD does not return within that time will + * the CEC adapter be unregistered. + * + * If it is set to a value >= NEVER_UNREG_DELAY, then the CEC adapter will never + * be unregistered for as long as the connector remains registered. + * + * If it is set to 0, then the CEC adapter will be unregistered immediately as + * soon as the HPD disappears. + * + * The default is one second to prevent short HPD glitches from unregistering + * the CEC adapter. + * + * Note that for integrated HDMI branch devices that support CEC the DPCD + * registers remain available even if the HPD goes low since it is not powered + * by the HPD. In that case the CEC adapter will never be unregistered during + * the life time of the connector. At least, this is the theory since I do not + * have hardware with an integrated HDMI branch device that supports CEC. + */ +#define NEVER_UNREG_DELAY 1000 +static unsigned int drm_dp_cec_unregister_delay = 1; +module_param(drm_dp_cec_unregister_delay, uint, 0600); +MODULE_PARM_DESC(drm_dp_cec_unregister_delay, + "CEC unregister delay in seconds, 0: no delay, >= 1000: never unregister"); + +static int drm_dp_cec_adap_enable(struct cec_adapter *adap, bool enable) +{ + struct drm_dp_aux *aux = cec_get_drvdata(adap); + u32 val = enable ? DP_CEC_TUNNELING_ENABLE : 0; + ssize_t err = 0; + + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val); + return (enable && err < 0) ? err : 0; +} + +static int drm_dp_cec_adap_log_addr(struct cec_adapter *adap, u8 addr) +{ + struct drm_dp_aux *aux = cec_get_drvdata(adap); + /* Bit 15 (logical address 15) should always be set */ + u16 la_mask = 1 << CEC_LOG_ADDR_BROADCAST; + u8 mask[2]; + ssize_t err; + + if (addr != CEC_LOG_ADDR_INVALID) + la_mask |= adap->log_addrs.log_addr_mask | (1 << addr); + mask[0] = la_mask & 0xff; + mask[1] = la_mask >> 8; + err = drm_dp_dpcd_write(aux, DP_CEC_LOGICAL_ADDRESS_MASK, mask, 2); + return (addr != CEC_LOG_ADDR_INVALID && err < 0) ? err : 0; +} + +static int drm_dp_cec_adap_transmit(struct cec_adapter *adap, u8 attempts, + u32 signal_free_time, struct cec_msg *msg) +{ + struct drm_dp_aux *aux = cec_get_drvdata(adap); + unsigned int retries = min(5, attempts - 1); + ssize_t err; + + err = drm_dp_dpcd_write(aux, DP_CEC_TX_MESSAGE_BUFFER, + msg->msg, msg->len); + if (err < 0) + return err; + + err = drm_dp_dpcd_writeb(aux, DP_CEC_TX_MESSAGE_INFO, + (msg->len - 1) | (retries << 4) | + DP_CEC_TX_MESSAGE_SEND); + return err < 0 ? err : 0; +} + +static int drm_dp_cec_adap_monitor_all_enable(struct cec_adapter *adap, + bool enable) +{ + struct drm_dp_aux *aux = cec_get_drvdata(adap); + ssize_t err; + u8 val; + + if (!(adap->capabilities & CEC_CAP_MONITOR_ALL)) + return 0; + + err = drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CONTROL, &val); + if (err >= 0) { + if (enable) + val |= DP_CEC_SNOOPING_ENABLE; + else + val &= ~DP_CEC_SNOOPING_ENABLE; + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val); + } + return (enable && err < 0) ? err : 0; +} + +static void drm_dp_cec_adap_status(struct cec_adapter *adap, + struct seq_file *file) +{ + struct drm_dp_aux *aux = cec_get_drvdata(adap); + struct drm_dp_desc desc; + struct drm_dp_dpcd_ident *id = &desc.ident; + + if (drm_dp_read_desc(aux, &desc, true)) + return; + seq_printf(file, "OUI: %*pdH\n", + (int)sizeof(id->oui), id->oui); + seq_printf(file, "ID: %*pE\n", + (int)strnlen(id->device_id, sizeof(id->device_id)), + id->device_id); + seq_printf(file, "HW Rev: %d.%d\n", id->hw_rev >> 4, id->hw_rev & 0xf); + /* + * Show this both in decimal and hex: at least one vendor + * always reports this in hex. + */ + seq_printf(file, "FW/SW Rev: %d.%d (0x%02x.0x%02x)\n", + id->sw_major_rev, id->sw_minor_rev, + id->sw_major_rev, id->sw_minor_rev); +} + +static const struct cec_adap_ops drm_dp_cec_adap_ops = { + .adap_enable = drm_dp_cec_adap_enable, + .adap_log_addr = drm_dp_cec_adap_log_addr, + .adap_transmit = drm_dp_cec_adap_transmit, + .adap_monitor_all_enable = drm_dp_cec_adap_monitor_all_enable, + .adap_status = drm_dp_cec_adap_status, +}; + +static int drm_dp_cec_received(struct drm_dp_aux *aux) +{ + struct cec_adapter *adap = aux->cec.adap; + struct cec_msg msg; + u8 rx_msg_info; + ssize_t err; + + err = drm_dp_dpcd_readb(aux, DP_CEC_RX_MESSAGE_INFO, &rx_msg_info); + if (err < 0) + return err; + + if (!(rx_msg_info & DP_CEC_RX_MESSAGE_ENDED)) + return 0; + + msg.len = (rx_msg_info & DP_CEC_RX_MESSAGE_LEN_MASK) + 1; + err = drm_dp_dpcd_read(aux, DP_CEC_RX_MESSAGE_BUFFER, msg.msg, msg.len); + if (err < 0) + return err; + + cec_received_msg(adap, &msg); + return 0; +} + +static void drm_dp_cec_handle_irq(struct drm_dp_aux *aux) +{ + struct cec_adapter *adap = aux->cec.adap; + u8 flags; + + if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, &flags) < 0) + return; + + if (flags & DP_CEC_RX_MESSAGE_INFO_VALID) + drm_dp_cec_received(aux); + + if (flags & DP_CEC_TX_MESSAGE_SENT) + cec_transmit_attempt_done(adap, CEC_TX_STATUS_OK); + else if (flags & DP_CEC_TX_LINE_ERROR) + cec_transmit_attempt_done(adap, CEC_TX_STATUS_ERROR | + CEC_TX_STATUS_MAX_RETRIES); + else if (flags & + (DP_CEC_TX_ADDRESS_NACK_ERROR | DP_CEC_TX_DATA_NACK_ERROR)) + cec_transmit_attempt_done(adap, CEC_TX_STATUS_NACK | + CEC_TX_STATUS_MAX_RETRIES); + drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, flags); +} + +/** + * drm_dp_cec_irq() - handle CEC interrupt, if any + * @aux: DisplayPort AUX channel + * + * Should be called when handling an IRQ_HPD request. If CEC-tunneling-over-AUX + * is present, then it will check for a CEC_IRQ and handle it accordingly. + */ +void drm_dp_cec_irq(struct drm_dp_aux *aux) +{ + u8 cec_irq; + int ret; + + mutex_lock(&aux->cec.lock); + if (!aux->cec.adap) + goto unlock; + + ret = drm_dp_dpcd_readb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1, + &cec_irq); + if (ret < 0 || !(cec_irq & DP_CEC_IRQ)) + goto unlock; + + drm_dp_cec_handle_irq(aux); + drm_dp_dpcd_writeb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1, DP_CEC_IRQ); +unlock: + mutex_unlock(&aux->cec.lock); +} +EXPORT_SYMBOL(drm_dp_cec_irq); + +static bool drm_dp_cec_cap(struct drm_dp_aux *aux, u8 *cec_cap) +{ + u8 cap = 0; + + if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CAPABILITY, &cap) != 1 || + !(cap & DP_CEC_TUNNELING_CAPABLE)) + return false; + if (cec_cap) + *cec_cap = cap; + return true; +} + +/* + * Called if the HPD was low for more than drm_dp_cec_unregister_delay + * seconds. This unregisters the CEC adapter. + */ +static void drm_dp_cec_unregister_work(struct work_struct *work) +{ + struct drm_dp_aux *aux = container_of(work, struct drm_dp_aux, + cec.unregister_work.work); + + if (!aux->cec.adap) + return; + mutex_lock(&aux->cec.lock); + cec_unregister_adapter(aux->cec.adap); + aux->cec.adap = NULL; + mutex_unlock(&aux->cec.lock); +} + +/* + * A new EDID is set. If there is no CEC adapter, then create one. If + * there was a CEC adapter, then check if the CEC adapter properties + * were unchanged and just update the CEC physical address. Otherwise + * unregister the old CEC adapter and create a new one. + */ +void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid) +{ + u32 cec_caps = CEC_CAP_DEFAULTS | CEC_CAP_NEEDS_HPD; + unsigned int num_las = 1; + u8 cap; + +#ifndef CONFIG_MEDIA_CEC_RC + /* + * CEC_CAP_RC is part of CEC_CAP_DEFAULTS, but it is stripped by + * cec_allocate_adapter() if CONFIG_MEDIA_CEC_RC is undefined. + * + * Do this here as well to ensure the tests against cec_caps are + * correct. + */ + cec_caps &= ~CEC_CAP_RC; +#endif + cancel_delayed_work_sync(&aux->cec.unregister_work); + + mutex_lock(&aux->cec.lock); + if (!drm_dp_cec_cap(aux, &cap)) { + /* CEC is not supported, unregister any existing adapter */ + cec_unregister_adapter(aux->cec.adap); + aux->cec.adap = NULL; + goto unlock; + } + + if (cap & DP_CEC_SNOOPING_CAPABLE) + cec_caps |= CEC_CAP_MONITOR_ALL; + if (cap & DP_CEC_MULTIPLE_LA_CAPABLE) + num_las = CEC_MAX_LOG_ADDRS; + + if (aux->cec.adap) { + if (aux->cec.adap->capabilities == cec_caps && + aux->cec.adap->available_log_addrs == num_las) { + /* Unchanged, so just set the phys addr */ + cec_s_phys_addr_from_edid(aux->cec.adap, edid); + goto unlock; + } + /* + * The capabilities changed, so unregister the old + * adapter first. + */ + cec_unregister_adapter(aux->cec.adap); + } + + /* Create a new adapter */ + aux->cec.adap = cec_allocate_adapter(&drm_dp_cec_adap_ops, + aux, aux->cec.name, cec_caps, + num_las); + if (IS_ERR(aux->cec.adap)) { + aux->cec.adap = NULL; + goto unlock; + } + if (cec_register_adapter(aux->cec.adap, aux->cec.parent)) { + cec_delete_adapter(aux->cec.adap); + aux->cec.adap = NULL; + } else { + /* + * Update the phys addr for the new CEC adapter. When called + * from drm_dp_cec_register_connector() edid == NULL, so in + * that case the phys addr is just invalidated. + */ + cec_s_phys_addr_from_edid(aux->cec.adap, edid); + } +unlock: + mutex_unlock(&aux->cec.lock); +} +EXPORT_SYMBOL(drm_dp_cec_set_edid); + +/* + * The EDID disappeared (likely because of the HPD going down). + */ +void drm_dp_cec_unset_edid(struct drm_dp_aux *aux) +{ + mutex_lock(&aux->cec.lock); + if (!aux->cec.adap) + goto unlock; + cec_phys_addr_invalidate(aux->cec.adap); + /* + * We're done if we want to keep the CEC device + * (drm_dp_cec_unregister_delay is >= NEVER_UNREG_DELAY) or if the + * DPCD still indicates the CEC capability (expected for an integrated + * HDMI branch device). + */ + if (drm_dp_cec_unregister_delay >= NEVER_UNREG_DELAY || + drm_dp_cec_cap(aux, NULL)) + goto unlock; + + mutex_unlock(&aux->cec.lock); + cancel_delayed_work_sync(&aux->cec.unregister_work); + mutex_lock(&aux->cec.lock); + + if (aux->cec.adap) { + /* + * Unregister the CEC adapter after drm_dp_cec_unregister_delay + * seconds. This to debounce short HPD off-and-on cycles from + * displays. + */ + schedule_delayed_work(&aux->cec.unregister_work, + drm_dp_cec_unregister_delay * HZ); + } +unlock: + mutex_unlock(&aux->cec.lock); +} +EXPORT_SYMBOL(drm_dp_cec_unset_edid); + +/** + * drm_dp_cec_register_connector() - register a new connector + * @aux: DisplayPort AUX channel + * @name: name of the CEC device + * @parent: parent device + * + * A new connector was registered with associated CEC adapter name and + * CEC adapter parent device. After registering the name and parent + * drm_dp_cec_set_edid() is called to check if the connector supports + * CEC and to register a CEC adapter if that is the case. + */ +void drm_dp_cec_register_connector(struct drm_dp_aux *aux, const char *name, + struct device *parent) +{ + WARN_ON(aux->cec.adap); + aux->cec.name = name; + aux->cec.parent = parent; + INIT_DELAYED_WORK(&aux->cec.unregister_work, drm_dp_cec_unregister_work); + + drm_dp_cec_set_edid(aux, NULL); +} +EXPORT_SYMBOL(drm_dp_cec_register_connector); + +/** + * drm_dp_cec_unregister_connector() - unregister the CEC adapter, if any + * @aux: DisplayPort AUX channel + */ +void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux) +{ + if (!aux->cec.adap) + return; + cancel_delayed_work_sync(&aux->cec.unregister_work); + cec_unregister_adapter(aux->cec.adap); + aux->cec.adap = NULL; +} +EXPORT_SYMBOL(drm_dp_cec_unregister_connector); diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c index a7ba602a43a8..f4a06b54aa7d 100644 --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -1087,6 +1087,7 @@ static void drm_dp_aux_crc_work(struct work_struct *work) void drm_dp_aux_init(struct drm_dp_aux *aux) { mutex_init(&aux->hw_mutex); + mutex_init(&aux->cec.lock); INIT_WORK(&aux->crc_work, drm_dp_aux_crc_work); aux->ddc.algo = &drm_dp_i2c_algo; diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index c01564991a9f..d0a23db271dc 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -1078,6 +1078,25 @@ struct drm_dp_aux_msg { size_t size; }; +struct cec_adapter; +struct edid; + +/** + * struct drm_dp_aux_cec - DisplayPort CEC-Tunneling-over-AUX + * @lock: mutex protecting this struct + * @adap: the CEC adapter for CEC-Tunneling-over-AUX support. + * @name: name of the CEC adapter + * @parent: parent device of the CEC adapter + * @unregister_work: unregister the CEC adapter + */ +struct drm_dp_aux_cec { + struct mutex lock; + struct cec_adapter *adap; + const char *name; + struct device *parent; + struct delayed_work unregister_work; +}; + /** * struct drm_dp_aux - DisplayPort AUX channel * @name: user-visible name of this AUX channel and the I2C-over-AUX adapter @@ -1136,6 +1155,10 @@ struct drm_dp_aux { * @i2c_defer_count: Counts I2C DEFERs, used for DP validation. */ unsigned i2c_defer_count; + /** + * @cec: struct containing fields used for CEC-Tunneling-over-AUX. + */ + struct drm_dp_aux_cec cec; }; ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, @@ -1258,4 +1281,37 @@ drm_dp_has_quirk(const struct drm_dp_desc *desc, enum drm_dp_quirk quirk) return desc->quirks & BIT(quirk); } +#ifdef CONFIG_DRM_DP_CEC +void drm_dp_cec_irq(struct drm_dp_aux *aux); +void drm_dp_cec_register_connector(struct drm_dp_aux *aux, const char *name, + struct device *parent); +void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux); +void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid); +void drm_dp_cec_unset_edid(struct drm_dp_aux *aux); +#else +static inline void drm_dp_cec_irq(struct drm_dp_aux *aux) +{ +} + +static inline void drm_dp_cec_register_connector(struct drm_dp_aux *aux, + const char *name, + struct device *parent) +{ +} + +static inline void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux) +{ +} + +static inline void drm_dp_cec_set_edid(struct drm_dp_aux *aux, + const struct edid *edid) +{ +} + +static inline void drm_dp_cec_unset_edid(struct drm_dp_aux *aux) +{ +} + +#endif + #endif /* _DRM_DP_HELPER_H_ */