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pwm: lpss: Use DPM_FLAG_NO_DIRECT_COMPLETE instead of declaring a prepare handler

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ACPI LPSS devices use direct-complete style suspend/resume handling by
default. We set the DPM_FLAG_SMART_PREPARE and define a prepare handler
to disable this on Cherry Trail devices.

Clean this up a bit by setting the DPM_FLAG_NO_DIRECT_COMPLETE flag for
Cherry Trail devices, instead of defining a prepare handler.

While at it also improve the comment explaining why this is necessary.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Hans de Goede 2020-11-09 11:57:25 +01:00 committed by Thierry Reding
parent d58560e6fa
commit b9c90f153d
1 changed files with 15 additions and 20 deletions
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35
drivers/pwm/pwm-lpss-platform.c
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@ -58,7 +58,21 @@ static int pwm_lpss_probe_platform(struct platform_device *pdev)
platform_set_drvdata(pdev, lpwm);
dev_pm_set_driver_flags(&pdev->dev, DPM_FLAG_SMART_PREPARE);
/*
* 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
*/
if (info->other_devices_aml_touches_pwm_regs)
dev_pm_set_driver_flags(&pdev->dev, DPM_FLAG_NO_DIRECT_COMPLETE);
pm_runtime_set_active(&pdev->dev);
pm_runtime_enable(&pdev->dev);
@ -73,24 +87,6 @@ static int pwm_lpss_remove_platform(struct platform_device *pdev)
return pwm_lpss_remove(lpwm);
}
static int pwm_lpss_prepare(struct device *dev)
{
struct pwm_lpss_chip *lpwm = dev_get_drvdata(dev);
/*
* If other device's AML code touches the PWM regs on suspend/resume
* force runtime-resume the PWM controller to allow this.
*/
if (lpwm->info->other_devices_aml_touches_pwm_regs)
return 0; /* Force runtime-resume */
return 1; /* If runtime-suspended leave as is */
}
static const struct dev_pm_ops pwm_lpss_platform_pm_ops = {
.prepare = pwm_lpss_prepare,
};
static const struct acpi_device_id pwm_lpss_acpi_match[] = {
{ "80860F09", (unsigned long)&pwm_lpss_byt_info },
{ "80862288", (unsigned long)&pwm_lpss_bsw_info },
@ -104,7 +100,6 @@ static struct platform_driver pwm_lpss_driver_platform = {
.driver = {
.name = "pwm-lpss",
.acpi_match_table = pwm_lpss_acpi_match,
.pm = &pwm_lpss_platform_pm_ops,
},
.probe = pwm_lpss_probe_platform,
.remove = pwm_lpss_remove_platform,