[Intel-gfx] [PATCH 11/15] drm/i915: Protect DSPARB registers with a spinlock

[Maarten Lankhorst]

Op 28-11-16 om 18:37 schreef ville.syrjala at linux.intel.com:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Each DSPARB register can house bits for two separate pipes, hence
> we must protect the registers during reprogramming so that parallel
> FIFO reconfigurations happening simultaneosly on multiple pipes won't
> corrupt each others values.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c | 1 +
>  drivers/gpu/drm/i915/i915_drv.h | 3 +++
>  drivers/gpu/drm/i915/intel_pm.c | 6 ++++++
>  3 files changed, 10 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 0fba4bb5655e..c98032e9112b 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -811,6 +811,7 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv,
>  	spin_lock_init(&dev_priv->uncore.lock);
>  	spin_lock_init(&dev_priv->mm.object_stat_lock);
>  	spin_lock_init(&dev_priv->mmio_flip_lock);
> +	spin_lock_init(&dev_priv->wm.dsparb_lock);
Can we make sure all wm updates are done with dev_priv->wm.wm_mutex held instead?

gen9 wm's and ilk wm's use that mutex, for similar reasons.
>  	mutex_init(&dev_priv->sb_lock);
>  	mutex_init(&dev_priv->modeset_restore_lock);
>  	mutex_init(&dev_priv->av_mutex);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 9d808b706824..75439e9a67f7 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2169,6 +2169,9 @@ struct drm_i915_private {
>  	} sagv_status;
>  
>  	struct {
> +		/* protects DSPARB registers on pre-g4x/vlv/chv */
> +		spinlock_t dsparb_lock;
> +
>  		/*
>  		 * Raw watermark latency values:
>  		 * in 0.1us units for WM0,
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 24d85a4e4ed3..9f25f2195a6a 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -1215,6 +1215,8 @@ static void vlv_pipe_set_fifo_size(struct intel_crtc *crtc)
>  		      pipe_name(crtc->pipe), sprite0_start,
>  		      sprite1_start, fifo_size);
>  
> +	spin_lock(&dev_priv->wm.dsparb_lock);
> +
>  	switch (crtc->pipe) {
>  		uint32_t dsparb, dsparb2, dsparb3;
>  	case PIPE_A:
> @@ -1271,6 +1273,10 @@ static void vlv_pipe_set_fifo_size(struct intel_crtc *crtc)
>  	default:
>  		break;
>  	}
> +
> +	POSTING_READ(DSPARB);
> +
> +	spin_unlock(&dev_priv->wm.dsparb_lock);
>  }
>  
>  #undef VLV_FIFO