[Intel-gfx] [PATCH 1/5] drm/i915: Add intel_display_power_{get, put} to request power for specific domains

Paulo Zanoni przanoni at gmail.com
Fri Sep 13 22:05:59 CEST 2013


Hi

2013/9/12  <ville.syrjala at linux.intel.com>:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Add APIs to get/put power well references for specific purposes.
>
> Also reorganize the internal i915_request power well handling to use the
> reference count just like everyone else. This way all we need to do is
> check the reference count and we know whether the power well needs to be
> enabled of disabled.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_drv.h |  4 ++
>  drivers/gpu/drm/i915/intel_pm.c  | 92 ++++++++++++++++++++++++++++++++++++----
>  2 files changed, 87 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 774ebb6..2ecd3d2 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -763,6 +763,10 @@ extern void i915_remove_power_well(struct drm_device *dev);
>
>  extern bool intel_display_power_enabled(struct drm_device *dev,
>                                         enum intel_display_power_domain domain);
> +extern void intel_display_power_get(struct drm_device *dev,
> +                                   enum intel_display_power_domain domain);
> +extern void intel_display_power_put(struct drm_device *dev,
> +                                   enum intel_display_power_domain domain);
>  extern void intel_init_power_well(struct drm_device *dev);
>  extern void intel_set_power_well(struct drm_device *dev, bool enable);
>  extern void intel_enable_gt_powersave(struct drm_device *dev);
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 8cffef4..4962303 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -5333,6 +5333,69 @@ static void __intel_set_power_well(struct drm_device *dev, bool enable)
>         }
>  }
>
> +void intel_display_power_get(struct drm_device *dev,
> +                            enum intel_display_power_domain domain)
> +{
> +       struct drm_i915_private *dev_priv = dev->dev_private;
> +       struct i915_power_well *power_well = &dev_priv->power_well;
> +
> +       if (!HAS_POWER_WELL(dev))
> +               return;
> +
> +       switch (domain) {
> +       case POWER_DOMAIN_PIPE_A:
> +       case POWER_DOMAIN_TRANSCODER_EDP:
> +               return;
> +       case POWER_DOMAIN_PIPE_B:
> +       case POWER_DOMAIN_PIPE_C:
> +       case POWER_DOMAIN_PIPE_A_PANEL_FITTER:
> +       case POWER_DOMAIN_PIPE_B_PANEL_FITTER:
> +       case POWER_DOMAIN_PIPE_C_PANEL_FITTER:
> +       case POWER_DOMAIN_TRANSCODER_A:
> +       case POWER_DOMAIN_TRANSCODER_B:
> +       case POWER_DOMAIN_TRANSCODER_C:

I know I'm the one who added all these domains, but I have to say I
only did this because of the reviewers, I don't really like the
interface. With your addition there's a new problem: you can get the
POWER_DOMAIN_PIPE_B interface and then put the
POWER_COMAIN_PIPE_C_PANEL_FITTER and no one will notice. I really
think the power well itself should be the domain. Also, in cases like
the suspend/resume code we don't have any domain that makes sense. But
what's *not* ugly about the power well code?

I'm not suggesting you to fix that, I'm more kinda asking for ideas, I
may want to reorganize this code yet again when doing the D3 feature.
(Just because every single time we touch the power well code we have
to refactor it!)


> +               spin_lock_irq(&power_well->lock);
> +               if (!power_well->count++)
> +                       __intel_set_power_well(power_well->device, true);
> +               spin_unlock_irq(&power_well->lock);
> +               return;
> +       default:
> +               BUG();
> +       }
> +}
> +
> +void intel_display_power_put(struct drm_device *dev,
> +                            enum intel_display_power_domain domain)
> +{
> +       struct drm_i915_private *dev_priv = dev->dev_private;
> +       struct i915_power_well *power_well = &dev_priv->power_well;
> +
> +       if (!HAS_POWER_WELL(dev))
> +               return;
> +
> +       switch (domain) {
> +       case POWER_DOMAIN_PIPE_A:
> +       case POWER_DOMAIN_TRANSCODER_EDP:
> +               return;
> +       case POWER_DOMAIN_PIPE_B:
> +       case POWER_DOMAIN_PIPE_C:
> +       case POWER_DOMAIN_PIPE_A_PANEL_FITTER:
> +       case POWER_DOMAIN_PIPE_B_PANEL_FITTER:
> +       case POWER_DOMAIN_PIPE_C_PANEL_FITTER:
> +       case POWER_DOMAIN_TRANSCODER_A:
> +       case POWER_DOMAIN_TRANSCODER_B:
> +       case POWER_DOMAIN_TRANSCODER_C:
> +               spin_lock_irq(&power_well->lock);
> +               WARN_ON(!power_well->count);
> +               if (!--power_well->count)
> +                       __intel_set_power_well(power_well->device, false);
> +               spin_unlock_irq(&power_well->lock);
> +               return;
> +       default:
> +               BUG();
> +       }
> +}
> +
>  static struct i915_power_well *hsw_pwr;
>
>  /* Display audio driver power well request */
> @@ -5342,8 +5405,7 @@ void i915_request_power_well(void)
>                 return;
>
>         spin_lock_irq(&hsw_pwr->lock);
> -       if (!hsw_pwr->count++ &&
> -                       !hsw_pwr->i915_request)
> +       if (!hsw_pwr->count++)
>                 __intel_set_power_well(hsw_pwr->device, true);
>         spin_unlock_irq(&hsw_pwr->lock);
>  }
> @@ -5357,8 +5419,7 @@ void i915_release_power_well(void)
>
>         spin_lock_irq(&hsw_pwr->lock);
>         WARN_ON(!hsw_pwr->count);
> -       if (!--hsw_pwr->count &&
> -                      !hsw_pwr->i915_request)
> +       if (!--hsw_pwr->count)
>                 __intel_set_power_well(hsw_pwr->device, false);
>         spin_unlock_irq(&hsw_pwr->lock);
>  }
> @@ -5394,15 +5455,28 @@ void intel_set_power_well(struct drm_device *dev, bool enable)
>                 return;
>
>         spin_lock_irq(&power_well->lock);
> +
> +       /*
> +        * This function will only ever contribute one
> +        * to the power well reference count. i915_request
> +        * is what tracks whether we have or have not
> +        * added the one to the reference count.
> +        */
> +       if (power_well->i915_request == enable)
> +               goto out;
> +
>         power_well->i915_request = enable;
>
> -       /* only reject "disable" power well request */
> -       if (power_well->count && !enable) {
> -               spin_unlock_irq(&power_well->lock);
> -               return;

And now to the real problem of the patch: previously whenever we got a
call to "enable" we'd call __intel_set_power_well and certainly write
the register. Now with this patch we may not do this due to
i915_request and the count. This breaks suspend/resume where just
after we resume we call intel_set_power_well(dev, true) but then the
new code doesn't really writes the register since i915_request is
already true. As a consequence, we see "unclaimed register" messages
complaining about registers 70008, 71008 and 72008. Perhaps in the
resume path we should fix our tracking and force the "enable" somehow.


> +       if (enable) {
> +               if (!power_well->count++)
> +                       __intel_set_power_well(dev, true);
> +       } else {
> +               WARN_ON(!power_well->count);
> +               if (!--power_well->count)
> +                       __intel_set_power_well(dev, false);
>         }
>
> -       __intel_set_power_well(dev, enable);
> + out:
>         spin_unlock_irq(&power_well->lock);
>  }
>
> --
> 1.8.1.5
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx



-- 
Paulo Zanoni



More information about the Intel-gfx mailing list