Re: [Intel-gfx] [PATCH] drm/i915: Remove runtime suspended boolean from intel_runtime_pm struct

[Jani Nikula <jani.nikula@intel.com>]

On Wed, 13 Sep 2023, Jouni Högander <jouni.hogander@intel.com> wrote:
> It's not necessary to carry separate suspended status information in
> intel_runtime_pm struct as this information is already in underlying device
> structure. Remove it and use pm_runtime_suspended() to obtain suspended
> status information when needed.

I started wondering if this is racy, and my conclusion is that it's
"less" racy than the original. rpm->suspended gets toggled in the middle
of the suspend/resume sequences. So it could be halfway. Dunno if
anything *after* those toggles depends on the state having been changed
already; didn't find any. Maybe Imre has a better idea.

Also, pm_runtime_suspended() seems more reliable when suspend/resume
fails.

Acked-by: Jani Nikula <jani.nikula@intel.com>


>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Imre Deak <imre.deak@intel.com>
>
> Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display_power.c | 2 +-
>  drivers/gpu/drm/i915/i915_driver.c                 | 3 ---
>  drivers/gpu/drm/i915/i915_gpu_error.c              | 2 +-
>  drivers/gpu/drm/i915/intel_runtime_pm.c            | 1 -
>  drivers/gpu/drm/i915/intel_runtime_pm.h            | 4 ++--
>  5 files changed, 4 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
> index 68cf5e6b0b46..889bb26009a2 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_power.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_power.c
> @@ -216,7 +216,7 @@ bool __intel_display_power_is_enabled(struct drm_i915_private *dev_priv,
>  	struct i915_power_well *power_well;
>  	bool is_enabled;
>  
> -	if (dev_priv->runtime_pm.suspended)
> +	if (pm_runtime_suspended(dev_priv->drm.dev))
>  		return false;
>  
>  	is_enabled = true;
> diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
> index f8dbee7a5af7..cd98ee740976 100644
> --- a/drivers/gpu/drm/i915/i915_driver.c
> +++ b/drivers/gpu/drm/i915/i915_driver.c
> @@ -1569,8 +1569,6 @@ static int intel_runtime_suspend(struct device *kdev)
>  	if (root_pdev)
>  		pci_d3cold_disable(root_pdev);
>  
> -	rpm->suspended = true;
> -
>  	/*
>  	 * FIXME: We really should find a document that references the arguments
>  	 * used below!
> @@ -1621,7 +1619,6 @@ static int intel_runtime_resume(struct device *kdev)
>  	disable_rpm_wakeref_asserts(rpm);
>  
>  	intel_opregion_notify_adapter(dev_priv, PCI_D0);
> -	rpm->suspended = false;
>  
>  	root_pdev = pcie_find_root_port(pdev);
>  	if (root_pdev)
> diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
> index 4008bb09fdb5..a60bab177c55 100644
> --- a/drivers/gpu/drm/i915/i915_gpu_error.c
> +++ b/drivers/gpu/drm/i915/i915_gpu_error.c
> @@ -1972,7 +1972,7 @@ static void capture_gen(struct i915_gpu_coredump *error)
>  	struct drm_i915_private *i915 = error->i915;
>  
>  	error->wakelock = atomic_read(&i915->runtime_pm.wakeref_count);
> -	error->suspended = i915->runtime_pm.suspended;
> +	error->suspended = pm_runtime_suspended(i915->drm.dev);
>  
>  	error->iommu = i915_vtd_active(i915);
>  	error->reset_count = i915_reset_count(&i915->gpu_error);
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> index 6d8e5e5c0cba..8743153fad87 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -652,7 +652,6 @@ void intel_runtime_pm_init_early(struct intel_runtime_pm *rpm)
>  
>  	rpm->kdev = kdev;
>  	rpm->available = HAS_RUNTIME_PM(i915);
> -	rpm->suspended = false;
>  	atomic_set(&rpm->wakeref_count, 0);
>  
>  	init_intel_runtime_pm_wakeref(rpm);
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.h b/drivers/gpu/drm/i915/intel_runtime_pm.h
> index 764b183ae452..f79cda7a2503 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.h
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.h
> @@ -6,6 +6,7 @@
>  #ifndef __INTEL_RUNTIME_PM_H__
>  #define __INTEL_RUNTIME_PM_H__
>  
> +#include <linux/pm_runtime.h>
>  #include <linux/types.h>
>  
>  #include "intel_wakeref.h"
> @@ -43,7 +44,6 @@ struct intel_runtime_pm {
>  	atomic_t wakeref_count;
>  	struct device *kdev; /* points to i915->drm.dev */
>  	bool available;
> -	bool suspended;
>  	bool irqs_enabled;
>  	bool no_wakeref_tracking;
>  
> @@ -110,7 +110,7 @@ intel_rpm_wakelock_count(int wakeref_count)
>  static inline void
>  assert_rpm_device_not_suspended(struct intel_runtime_pm *rpm)
>  {
> -	WARN_ONCE(rpm->suspended,
> +	WARN_ONCE(pm_runtime_suspended(rpm->kdev),
>  		  "Device suspended during HW access\n");
>  }

-- 
Jani Nikula, Intel