Messages in this thread Patch in this message | | | Date | Tue, 14 Dec 2021 10:49:49 +0000 | From | Cristian Marussi <> | Subject | Re: [PATCH v7 06/16] firmware: arm_scmi: Add configurable polling mode for transports |
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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
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