As the comment above the code setting the DPM_FLAG_NO_DIRECT_COMPLETE
flag explains:
/*
* On Cherry Trail devices the GFX0._PS0 AML checks if the controller
* is on and if it is not on it turns it on and restores what it
* believes is the correct state to the PWM controller.
* Because of this we must disallow direct-complete, which keeps the
* controller (runtime)suspended, on resume to avoid 2 issues:
* 1. The controller getting turned on without the linux-pm code
* knowing about this. On devices where the controller is unused
* this causes it to stay on during the next suspend causing high
* battery drain (because S0i3 is not reached)
* 2. The state restoring code unexpectedly messing with the controller
*/
The pm-core must not skip resume to avoid the GFX0._PS0 AML code messing
with the PWM controller behind our back. But leaving the controller
runtime-suspended (skipping runtime-resume + normal-suspend) during
suspend is fine. Set the DPM_FLAG_SMART_SUSPEND flag to allow this.
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
Changes in v2:
- Extend comment to explain why the DPM_FLAG_SMART_SUSPEND is set
---
drivers/pwm/pwm-lpss-platform.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/pwm/pwm-lpss-platform.c b/drivers/pwm/pwm-lpss-platform.c
index ac33861edb48..986786be1e49 100644
--- a/drivers/pwm/pwm-lpss-platform.c
+++ b/drivers/pwm/pwm-lpss-platform.c
@@ -69,9 +69,13 @@ static int pwm_lpss_probe_platform(struct platform_device *pdev)
* this causes it to stay on during the next suspend causing high
* battery drain (because S0i3 is not reached)
* 2. The state restoring code unexpectedly messing with the controller
+ *
+ * Leaving the controller runtime-suspended (skipping runtime-resume +
+ * normal-suspend) during suspend is fine.
*/
if (info->other_devices_aml_touches_pwm_regs)
- dev_pm_set_driver_flags(&pdev->dev, DPM_FLAG_NO_DIRECT_COMPLETE);
+ dev_pm_set_driver_flags(&pdev->dev, DPM_FLAG_NO_DIRECT_COMPLETE|
+ DPM_FLAG_SMART_SUSPEND);
pm_runtime_set_active(&pdev->dev);
pm_runtime_enable(&pdev->dev);
--
2.28.0
