| Message ID | 20211220195646.44498-2-cristian.marussi@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Introduce atomic support for SCMI transports | expand |
Hi, On 20/12/21 07:56PM, Cristian Marussi wrote: > SCMI communications along TX channels can optionally be provided of a > completion interrupt; when such interrupt is not available, command > transactions should rely on polling, where the SCMI core takes care to > repeatedly evaluate the transport-specific .poll_done() function, if > available, to determine if and when a request was fully completed or > timed out. > > Such mechanism is already present and working on a single transfer base: > SCMI protocols can indeed enable hdr.poll_completion on specific commands > ahead of each transfer and cause that transaction to be handled with > polling. > > Introduce a couple of flags to be able to enforce such polling behaviour > globally at will: > > - scmi_desc.force_polling: to statically switch the whole transport to > polling mode. > > - scmi_chan_info.no_completion_irq: to switch a single channel dynamically > to polling mode if, at runtime, is determined that no completion > interrupt was available for such channel. > > Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> This patch breaks linux-next build for me with LLVM. drivers/firmware/arm_scmi/driver.c:869:6: error: variable 'i_' is uninitialized when used within its own initialization [-Werror,-Wuninitialized] if (IS_POLLING_ENABLED(cinfo, info)) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/firmware/arm_scmi/driver.c:59:33: note: expanded from macro 'IS_POLLING_ENABLED' IS_TRANSPORT_POLLING_CAPABLE(i_)); \ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~ drivers/firmware/arm_scmi/driver.c:45:19: note: expanded from macro 'IS_TRANSPORT_POLLING_CAPABLE' typeof(__i) i_ = __i; \ ~~ ^~~ 1 error generated.
On Wed, Dec 22, 2021 at 01:08:54AM +0530, Pratyush Yadav wrote: > Hi, > > On 20/12/21 07:56PM, Cristian Marussi wrote: > > SCMI communications along TX channels can optionally be provided of a > > completion interrupt; when such interrupt is not available, command > > transactions should rely on polling, where the SCMI core takes care to > > repeatedly evaluate the transport-specific .poll_done() function, if > > available, to determine if and when a request was fully completed or > > timed out. > > > > Such mechanism is already present and working on a single transfer base: > > SCMI protocols can indeed enable hdr.poll_completion on specific commands > > ahead of each transfer and cause that transaction to be handled with > > polling. > > > > Introduce a couple of flags to be able to enforce such polling behaviour > > globally at will: > > > > - scmi_desc.force_polling: to statically switch the whole transport to > > polling mode. > > > > - scmi_chan_info.no_completion_irq: to switch a single channel dynamically > > to polling mode if, at runtime, is determined that no completion > > interrupt was available for such channel. > > > > Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> > > This patch breaks linux-next build for me with LLVM. > > drivers/firmware/arm_scmi/driver.c:869:6: error: variable 'i_' is uninitialized when used within its own initialization [-Werror,-Wuninitialized] > if (IS_POLLING_ENABLED(cinfo, info)) > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > drivers/firmware/arm_scmi/driver.c:59:33: note: expanded from macro 'IS_POLLING_ENABLED' > IS_TRANSPORT_POLLING_CAPABLE(i_)); \ > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~ > drivers/firmware/arm_scmi/driver.c:45:19: note: expanded from macro 'IS_TRANSPORT_POLLING_CAPABLE' > typeof(__i) i_ = __i; \ > ~~ ^~~ > 1 error generated. > Thanks for the report. The bot complained last night and I have pushed the update though not in time for linux-next today, must make it to tomorrow's cut. -- Regards, Sudeep
diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h index 6438b5248c24..652e5d95ee65 100644 --- a/drivers/firmware/arm_scmi/common.h +++ b/drivers/firmware/arm_scmi/common.h @@ -339,11 +339,16 @@ void scmi_protocol_release(const struct scmi_handle *handle, u8 protocol_id); * @dev: Reference to device in the SCMI hierarchy corresponding to this * channel * @handle: Pointer to SCMI entity handle + * @no_completion_irq: Flag to indicate that this channel has no completion + * interrupt mechanism for synchronous commands. + * This can be dynamically set by transports at run-time + * inside their provided .chan_setup(). * @transport_info: Transport layer related information */ struct scmi_chan_info { struct device *dev; struct scmi_handle *handle; + bool no_completion_irq; void *transport_info; }; @@ -402,6 +407,8 @@ struct scmi_device *scmi_child_dev_find(struct device *parent, * be pending simultaneously in the system. May be overridden by the * get_max_msg op. * @max_msg_size: Maximum size of data per message that can be handled. + * @force_polling: Flag to force this whole transport to use SCMI core polling + * mechanism instead of completion interrupts even if available. */ struct scmi_desc { int (*transport_init)(void); @@ -410,6 +417,7 @@ struct scmi_desc { int max_rx_timeout_ms; int max_msg; int max_msg_size; + const bool force_polling; }; #ifdef CONFIG_ARM_SCMI_TRANSPORT_MAILBOX diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c index 476b91845e40..cb9fc12503f2 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -36,6 +36,23 @@ #define CREATE_TRACE_POINTS #include <trace/events/scmi.h> +#define IS_POLLING_REQUIRED(__c, __i) \ + ((__c)->no_completion_irq || (__i)->desc->force_polling) \ + +#define IS_TRANSPORT_POLLING_CAPABLE(__i) \ + ((__i)->desc->ops->poll_done) + +#define IS_POLLING_ENABLED(__c, __i) \ +({ \ + bool __ret; \ + typeof(__c) c_ = __c; \ + typeof(__i) i_ = __i; \ + \ + __ret = (IS_POLLING_REQUIRED(c_, i_) && \ + IS_TRANSPORT_POLLING_CAPABLE(i_)); \ + __ret; \ +}) + enum scmi_error_codes { SCMI_SUCCESS = 0, /* Success */ SCMI_ERR_SUPPORT = -1, /* Not supported */ @@ -817,6 +834,7 @@ static int do_xfer(const struct scmi_protocol_handle *ph, struct device *dev = info->dev; struct scmi_chan_info *cinfo; + /* Check for polling request on custom command xfers at first */ if (xfer->hdr.poll_completion && !info->desc->ops->poll_done) { dev_warn_once(dev, "Polling mode is not supported by transport.\n"); @@ -827,6 +845,10 @@ static int do_xfer(const struct scmi_protocol_handle *ph, if (unlikely(!cinfo)) return -EINVAL; + /* True ONLY if also supported by transport. */ + if (IS_POLLING_ENABLED(cinfo, info)) + xfer->hdr.poll_completion = true; + /* * Initialise protocol id now from protocol handle to avoid it being * overridden by mistake (or malice) by the protocol code mangling with @@ -1527,6 +1549,16 @@ static int scmi_chan_setup(struct scmi_info *info, struct device *dev, if (ret) return ret; + if (tx && IS_POLLING_REQUIRED(cinfo, info)) { + if (IS_TRANSPORT_POLLING_CAPABLE(info)) + dev_info(dev, + "Enabled polling mode TX channel - prot_id:%d\n", + prot_id); + else + dev_warn(dev, + "Polling mode NOT supported by transport.\n"); + } + idr_alloc: ret = idr_alloc(idr, cinfo, prot_id, prot_id + 1, GFP_KERNEL); if (ret != prot_id) {
SCMI communications along TX channels can optionally be provided of a completion interrupt; when such interrupt is not available, command transactions should rely on polling, where the SCMI core takes care to repeatedly evaluate the transport-specific .poll_done() function, if available, to determine if and when a request was fully completed or timed out. Such mechanism is already present and working on a single transfer base: SCMI protocols can indeed enable hdr.poll_completion on specific commands ahead of each transfer and cause that transaction to be handled with polling. Introduce a couple of flags to be able to enforce such polling behaviour globally at will: - scmi_desc.force_polling: to statically switch the whole transport to polling mode. - scmi_chan_info.no_completion_irq: to switch a single channel dynamically to polling mode if, at runtime, is determined that no completion interrupt was available for such channel. Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> --- v7 --> v8 - removed internal poling_enabled flag, using macros v5 --> v6 - removed check on replies received by IRQs when xfer was requested as poll_completion (not all transport can suppress IRQs on an xfer basis) v4 --> v5 - make force_polling const - introduce polling_enabled flag to simplify checks on do_xfer v3 --> v4: - renamed .needs_polling flag to .no_completion_irq - refactored error path when polling needed but not supported --- drivers/firmware/arm_scmi/common.h | 8 ++++++++ drivers/firmware/arm_scmi/driver.c | 32 ++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+)