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

[Imre Deak]

On Wed, Sep 13, 2023 at 03:02:58PM +0300, Jani Nikula wrote:
> On Wed, 13 Sep 2023, Jouni Högander <jouni.hogander at 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.

The flag was added in the initial runtime PM enabling patch to detect
MMIO accesses while runtime suspended, looks like pm_runtime_suspended()
would've worked ok already at that point.

I wondered how the above detection would change in the system suspend /
resume handlers but that looks ok as well with the disable_depth check
in pm_runtime_suspended():
Reviewed-by: Imre Deak <imre.deak at intel.com>

> Acked-by: Jani Nikula <jani.nikula at intel.com>
> 
> 
> >
> > Cc: Jani Nikula <jani.nikula at intel.com>
> > Cc: Imre Deak <imre.deak at intel.com>
> >
> > Signed-off-by: Jouni Högander <jouni.hogander at 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