[PATCH v1] chrome/cros_ec: Handle events during suspend after resume completion

[PATCH v1] chrome/cros_ec: Handle events during suspend after resume completion

[Karthikeyan Ramasubramanian]

On boards where EC IRQ is not wake capable, EC does not trigger IRQ to
signal any non-wake events until EC receives host resume event.
Commit 47ea0ddb1f56 ("platform/chrome: cros_ec_lpc: Separate host
command and irq disable") separated enabling IRQ and sending resume
event host command into early_resume and resume_complete stages
respectively. This separation leads to host not handling certain events
posted during a small time window between early_resume and
resume_complete stages. This change moves handling all events that
happened during suspend after sending host resume event.

Fixes: 47ea0ddb1f56 ("platform/chrome: cros_ec_lpc: Separate host command and irq disable")
Cc: stable@vger.kernel.org
Cc: Lalith Rajendran <lalithkraj@chromium.org>
Cc: chrome-platform@lists.linux.dev
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@chromium.org>
---

 drivers/platform/chrome/cros_ec.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec.c b/drivers/platform/chrome/cros_ec.c
index badc68bbae8cc..41714df053916 100644
--- a/drivers/platform/chrome/cros_ec.c
+++ b/drivers/platform/chrome/cros_ec.c
@@ -432,6 +432,12 @@ static void cros_ec_send_resume_event(struct cros_ec_device *ec_dev)
 void cros_ec_resume_complete(struct cros_ec_device *ec_dev)
 {
 	cros_ec_send_resume_event(ec_dev);
+	/*
+	 * Let the mfd devices know about events that occur during
+	 * suspend. This way the clients know what to do with them.
+	 */
+	cros_ec_report_events_during_suspend(ec_dev);
+
 }
 EXPORT_SYMBOL(cros_ec_resume_complete);
 
@@ -442,12 +448,6 @@ static void cros_ec_enable_irq(struct cros_ec_device *ec_dev)
 
 	if (ec_dev->wake_enabled)
 		disable_irq_wake(ec_dev->irq);
-
-	/*
-	 * Let the mfd devices know about events that occur during
-	 * suspend. This way the clients know what to do with them.
-	 */
-	cros_ec_report_events_during_suspend(ec_dev);
 }
 
 /**
@@ -475,8 +475,9 @@ EXPORT_SYMBOL(cros_ec_resume_early);
  */
 int cros_ec_resume(struct cros_ec_device *ec_dev)
 {
-	cros_ec_enable_irq(ec_dev);
-	cros_ec_send_resume_event(ec_dev);
+	cros_ec_resume_early(ec_dev);
+	cros_ec_resume_complete(ec_dev);
+
 	return 0;
 }
 EXPORT_SYMBOL(cros_ec_resume);
-- 
2.44.0.769.g3c40516874-goog

Re: [PATCH v1] chrome/cros_ec: Handle events during suspend after resume completion

[Tzung-Bi Shih]

On Thu, Apr 25, 2024 at 02:37:11PM -0600, Karthikeyan Ramasubramanian wrote:
> On boards where EC IRQ is not wake capable, EC does not trigger IRQ to
> signal any non-wake events until EC receives host resume event.

The sentence looks irrelevant to the fix.  Presumably, EC should send those
pending non-wake events after it receives host resume event.

> Commit 47ea0ddb1f56 ("platform/chrome: cros_ec_lpc: Separate host
> command and irq disable") separated enabling IRQ and sending resume
> event host command into early_resume and resume_complete stages
> respectively. This separation leads to host not handling certain events
> posted during a small time window between early_resume and
> resume_complete stages. This change moves handling all events that
> happened during suspend after sending host resume event.

The regression you see is probably not due to the "separation" but an unwanted
code reorder.

Before 47ea0ddb1f56[1], a resume is:
1) Enable IRQ.
2) Send resume event.
3) Handle pending events.


After 47ea0ddb1f56[2], a resume is:
1) Enable IRQ.
2) Handle pending events.
3) Send resume event.

If there are some more events pending between 2) and 3), they would be handled
further late.

[1]: https://elixir.bootlin.com/linux/v6.6/source/drivers/platform/chrome/cros_ec.c#L381
[2]: https://elixir.bootlin.com/linux/v6.7/source/drivers/platform/chrome/cros_ec.c#L438


I see what the patch tries to fix but the commit message makes less sense to
me.  Please fix accordingly.