On Tue, Feb 02, 2016 at 11:06:26AM +0000, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
>
> RPS lock must be taken before the struct_mutex to avoid
> locking inversion. So stop grabbing it for the whole
> powersave initialization and instead only take it during
> the sections which need it.
>
> Also, struct_mutex is not needed any more since dedicated
> RPS lock was added in:
>
> commit 4fc688ce79772496503d22263d61b071a8fb596e
> Author: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
> Date: Fri Nov 2 11:14:01 2012 -0700
>
> drm/i915: protect RPS/RC6 related accesses (including PCU) with a new mutex
>
> Based on prototype patch by Chris Wilson and a subsequent
> mailing list discussion involving Ville, Imre, Chris and
> Daniel.
>
> v2: More details in the commit.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Imre Deak <imre.deak@xxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_display.c | 4 ----
> drivers/gpu/drm/i915/intel_pm.c | 9 +++++----
> 2 files changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 5018295cd92b..af0d33a3697a 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -15995,9 +15995,7 @@ void intel_modeset_gem_init(struct drm_device *dev)
> struct drm_i915_gem_object *obj;
> int ret;
>
> - mutex_lock(&dev->struct_mutex);
> intel_init_gt_powersave(dev);
> - mutex_unlock(&dev->struct_mutex);
>
> intel_modeset_init_hw(dev);
>
> @@ -16077,9 +16075,7 @@ void intel_modeset_cleanup(struct drm_device *dev)
>
> intel_cleanup_overlay(dev);
>
> - mutex_lock(&dev->struct_mutex);
> intel_cleanup_gt_powersave(dev);
> - mutex_unlock(&dev->struct_mutex);
The whitespace no longer conveys meaning, it used to be to clearly mark
the mutex section.
> @@ -5235,6 +5233,7 @@ static void valleyview_setup_pctx(struct drm_device *dev)
> out:
> DRM_DEBUG_DRIVER("PCBR: 0x%08x\n", I915_READ(VLV_PCBR));
> dev_priv->vlv_pctx = pctx;
> + mutex_unlock(&dev->struct_mutex);
> }
>
> static void valleyview_cleanup_pctx(struct drm_device *dev)
> @@ -5244,8 +5243,10 @@ static void valleyview_cleanup_pctx(struct drm_device *dev)
> if (WARN_ON(!dev_priv->vlv_pctx))
> return;
>
> + mutex_lock(&dev->struct_mutex);
> drm_gem_object_unreference(&dev_priv->vlv_pctx->base);
> dev_priv->vlv_pctx = NULL;
> + mutex_unlock(&dev->struct_mutex);
This made me smile.
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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