| Message ID | 20211129191156.29322-7-cristian.marussi@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Introduce atomic support for SCMI transports | expand |
On Mon, Nov 29, 2021 at 07:11:46PM +0000, 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> > --- > 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 | 11 +++++++++++ > drivers/firmware/arm_scmi/driver.c | 17 +++++++++++++++++ > 2 files changed, 28 insertions(+) > > diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h > index 6438b5248c24..99b74f4d39b6 100644 > --- a/drivers/firmware/arm_scmi/common.h > +++ b/drivers/firmware/arm_scmi/common.h > @@ -339,11 +339,19 @@ 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(). > + * @polling_enabled: Flag used to annotate if polling mode is currently enabled > + * on this channel. > * @transport_info: Transport layer related information > */ > struct scmi_chan_info { > struct device *dev; > struct scmi_handle *handle; > + bool no_completion_irq; > + bool polling_enabled; Do we really need a separate flag for polling_enabled ? no_completion_irq means you need to enable polling and force_polling too. Just trying to see if we can get rid of unnecessary flags.
On Mon, Dec 13, 2021 at 11:25:55AM +0000, Sudeep Holla wrote: > On Mon, Nov 29, 2021 at 07:11:46PM +0000, 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. > > Hi Sudeep, thanks for the review. > > 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> > > --- > > 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 | 11 +++++++++++ > > drivers/firmware/arm_scmi/driver.c | 17 +++++++++++++++++ > > 2 files changed, 28 insertions(+) > > > > diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h > > index 6438b5248c24..99b74f4d39b6 100644 > > --- a/drivers/firmware/arm_scmi/common.h > > +++ b/drivers/firmware/arm_scmi/common.h > > @@ -339,11 +339,19 @@ 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(). > > + * @polling_enabled: Flag used to annotate if polling mode is currently enabled > > + * on this channel. > > * @transport_info: Transport layer related information > > */ > > struct scmi_chan_info { > > struct device *dev; > > struct scmi_handle *handle; > > + bool no_completion_irq; > > + bool polling_enabled; > > Do we really need a separate flag for polling_enabled ? > no_completion_irq means you need to enable polling and force_polling too. > Just trying to see if we can get rid of unnecessary flags. > Not really needed indeed, I was just trying to avoid multiple conditions checks later on the TX path (given no_completion_irq and force_polling never change after channel setup so I can just note down at setup that polling is enabled and then just check that later) and improve readability, but I can just use macros for readability and just ignore the multiple unneeded checks. Same holds later on the series for polling_capable flag that I similarly setup early during probe to avoid unneeded multiple condition checks. I'll remove both this internal flags and resort to macros, if it's fine for you. Thanks, Cristian
diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h index 6438b5248c24..99b74f4d39b6 100644 --- a/drivers/firmware/arm_scmi/common.h +++ b/drivers/firmware/arm_scmi/common.h @@ -339,11 +339,19 @@ 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(). + * @polling_enabled: Flag used to annotate if polling mode is currently enabled + * on this channel. * @transport_info: Transport layer related information */ struct scmi_chan_info { struct device *dev; struct scmi_handle *handle; + bool no_completion_irq; + bool polling_enabled; void *transport_info; }; @@ -402,6 +410,8 @@ 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 +420,7 @@ 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..8a30b832899c 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -817,6 +817,7 @@ 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 +828,10 @@ static int do_xfer(const struct scmi_protocol_handle *ph, if (unlikely(!cinfo)) return -EINVAL; + /* Initialized to true ONLY if also supported by transport. */ + if (cinfo->polling_enabled) + 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 +1532,18 @@ static int scmi_chan_setup(struct scmi_info *info, struct device *dev, if (ret) return ret; + if (tx && (cinfo->no_completion_irq || info->desc->force_polling)) { + if (info->desc->ops->poll_done) { + dev_info(dev, + "Enabled polling mode TX channel - prot_id:%d\n", + prot_id); + cinfo->polling_enabled = true; + } 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> --- 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 | 11 +++++++++++ drivers/firmware/arm_scmi/driver.c | 17 +++++++++++++++++ 2 files changed, 28 insertions(+)