Re: [PATCH 14/24] drm/i915: Add dev_priv->wm.mutex

Paulo Zanoni
2014-04-23T21:47:05Z

2014-03-07 13:32 GMT-03:00 <ville.syrjala@linux.intel.com>:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Add a mutex to protect most of the watermark state. Will be useful when
> we start to update watermarks asynchronously from plane updates, or
> when we get finer grained locking for planes.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
> drivers/gpu/drm/i915/i915_drv.h | 11 ++++++++++-
> drivers/gpu/drm/i915/intel_drv.h | 5 ++++-
> drivers/gpu/drm/i915/intel_pm.c | 21 +++++++++++++++++++--
> 3 files changed, 33 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 29da39f..0b19723 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1595,8 +1595,17 @@ typedef struct drm_i915_private {
> /* cursor */
> uint16_t cur_latency[5];
>
> - /* current hardware state */
> + /*
> + * current hardware state
> + * protected by dev_priv->wm.mutex
> + */
> struct ilk_wm_values hw;
> +
> + /*
> + * protects some dev_priv->wm and intel_crtc->wm
> + * state as well as the actual hardware registers
> + */
> + struct mutex mutex;
> } wm;
>
> struct i915_package_c8 pc8;
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index f022a78..8e32d69 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -384,7 +384,10 @@ struct intel_crtc {
>
> /* per-pipe watermark state */
> struct {
> - /* watermarks currently being used */
> + /*
> + * watermarks currently being used
> + * protected by dev_priv->wm.mutex
> + */
> struct intel_pipe_wm active;
> } wm;
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 3f5c1dc..d8adcb3 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -2692,8 +2692,13 @@ static void ilk_write_wm_values(struct drm_i915_private *dev_priv,
> static bool ilk_disable_lp_wm(struct drm_device *dev)
> {
> struct drm_i915_private *dev_priv = dev->dev_private;
> + bool changed;
>
> - return _ilk_disable_lp_wm(dev_priv, WM_DIRTY_LP_ALL);
> + mutex_lock(&dev_priv->wm.mutex);
> + changed = _ilk_disable_lp_wm(dev_priv, WM_DIRTY_LP_ALL);
> + mutex_unlock(&dev_priv->wm.mutex);
> +
> + return changed;
> }
>
> static void ilk_program_watermarks(struct drm_device *dev)
> @@ -2733,6 +2738,7 @@ static void ilk_update_wm(struct drm_crtc *crtc)
> {
> struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> struct drm_device *dev = crtc->dev;
> + struct drm_i915_private *dev_priv = dev->dev_private;
> struct ilk_pipe_wm_parameters params = {};
> struct intel_pipe_wm pipe_wm = {};
>
> @@ -2740,12 +2746,17 @@ static void ilk_update_wm(struct drm_crtc *crtc)
>
> intel_compute_pipe_wm(crtc, &params, &pipe_wm);
>
> + mutex_lock(&dev_priv->wm.mutex);
> +
> if (!memcmp(&intel_crtc->wm.active, &pipe_wm, sizeof(pipe_wm)))
> - return;
> + goto unlock;
>
> intel_crtc->wm.active = pipe_wm;
>
> ilk_program_watermarks(dev);
> +
> + unlock:
> + mutex_unlock(&dev_priv->wm.mutex);
> }
>
> static void ilk_update_sprite_wm(struct drm_plane *plane,
> @@ -2817,10 +2828,14 @@ void ilk_wm_get_hw_state(struct drm_device *dev)
> struct drm_i915_private *dev_priv = dev->dev_private;
> struct drm_crtc *crtc;
>
> + mutex_lock(&dev_priv->wm.mutex);
> +
> _ilk_wm_get_hw_state(dev, &dev_priv->wm.hw);
>
> list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
> _ilk_pipe_wm_hw_to_sw(crtc);
> +
> + mutex_unlock(&dev_priv->wm.mutex);
> }
>
> /**
> @@ -5760,6 +5775,8 @@ void intel_init_pm(struct drm_device *dev)
> {
> struct drm_i915_private *dev_priv = dev->dev_private;
>
> + mutex_init(&dev_priv->wm.mutex);
> +

I think you should probably init this at intel_pm_setup(), which is
called way earlier. Just to be safe.

With that fixed: Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>.

> if (HAS_FBC(dev)) {
> if (INTEL_INFO(dev)->gen >= 7) {
> dev_priv->display.fbc_enabled = ironlake_fbc_enabled;
> --
> 1.8.3.2
>
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--
Paulo Zanoni