Re: [RFC 05/15] drm/i915: Lookup CRTC for plane directly

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, May 20, 2015 at 07:12:17PM -0700, Matt Roper wrote:
> Various places in the atomic plane code obtain the CRTC via
> plane_state->crtc.  But plane_state->crtc is NULL when disabling the
> plane, so the code will fall back to looking at the old CRTC value in
> plane->crtc in that case.  This isn't going to work when we start
> supporting non-blocking flips (since the legacy plane->crtc pointer will
> already be updated to its new value before the asynchronous workqueue
> task runs the plane commit function).  The code is also fragile in
> general (we have to be careful when doing stuff like updating properties
> on a disabled plane).  Since Intel hardware has a fixed plane to pipe
> mapping, let's just lookup the CRTC via that fixed mapping and avoid
> future mistakes.

Older gens have non-fixed mapping. So I think we should really be looking
at the state (future state in check, current state in commit). Sadly last
time I tried to do that the state was still all lies and resulted in
explosions. Dunno if things are better now.

> 
> Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
> Reported-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_atomic_plane.c | 12 ++++++------
>  drivers/gpu/drm/i915/intel_display.c      |  8 ++++----
>  drivers/gpu/drm/i915/intel_drv.h          |  7 +++++++
>  drivers/gpu/drm/i915/intel_sprite.c       |  4 ++--
>  4 files changed, 19 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_atomic_plane.c b/drivers/gpu/drm/i915/intel_atomic_plane.c
> index 714ee24..21c808d 100644
> --- a/drivers/gpu/drm/i915/intel_atomic_plane.c
> +++ b/drivers/gpu/drm/i915/intel_atomic_plane.c
> @@ -115,16 +115,16 @@ static int intel_plane_atomic_check(struct drm_plane *plane,
>  	struct intel_plane *intel_plane = to_intel_plane(plane);
>  	struct intel_plane_state *intel_state = to_intel_plane_state(state);
>  
> -	crtc = crtc ? crtc : plane->crtc;
> +	crtc = intel_get_crtc_for_drm_plane(plane);
>  	intel_crtc = to_intel_crtc(crtc);
>  
>  	/*
> -	 * Both crtc and plane->crtc could be NULL if we're updating a
> -	 * property while the plane is disabled.  We don't actually have
> -	 * anything driver-specific we need to test in that case, so
> -	 * just return success.
> +	 * Both state->crtc and plane->state->crtc could be NULL if we're
> +	 * updating a property while the plane is disabled.  We don't actually
> +	 * have anything driver-specific we need to test in that case, so just
> +	 * return success.
>  	 */
> -	if (!crtc)
> +	if (!state->crtc && !plane->state->crtc)
>  		return 0;
>  
>  	crtc_state = intel_crtc_state_for_plane(intel_state);
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 1a7d2a9..f4398a7 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -13092,7 +13092,7 @@ intel_check_primary_plane(struct drm_plane *plane,
>  	int min_scale = DRM_PLANE_HELPER_NO_SCALING;
>  	int ret;
>  
> -	crtc = crtc ? crtc : plane->crtc;
> +	crtc = intel_get_crtc_for_drm_plane(plane);
>  	intel_crtc = to_intel_crtc(crtc);
>  	crtc_state = intel_crtc_state_for_plane(state);
>  
> @@ -13174,7 +13174,7 @@ intel_commit_primary_plane(struct drm_plane *plane,
>  	struct intel_crtc *intel_crtc;
>  	struct drm_rect *src = &state->src;
>  
> -	crtc = crtc ? crtc : plane->crtc;
> +	crtc = intel_get_crtc_for_drm_plane(plane);
>  	intel_crtc = to_intel_crtc(crtc);
>  
>  	plane->fb = fb;
> @@ -13409,7 +13409,7 @@ intel_check_cursor_plane(struct drm_plane *plane,
>  	unsigned stride;
>  	int ret;
>  
> -	crtc = crtc ? crtc : plane->crtc;
> +	crtc = intel_get_crtc_for_drm_plane(plane);
>  	intel_crtc = to_intel_crtc(crtc);
>  
>  	ret = drm_plane_helper_check_update(plane, crtc, fb,
> @@ -13482,7 +13482,7 @@ intel_commit_cursor_plane(struct drm_plane *plane,
>  	struct drm_i915_gem_object *obj = intel_fb_obj(state->base.fb);
>  	uint32_t addr;
>  
> -	crtc = crtc ? crtc : plane->crtc;
> +	crtc = intel_get_crtc_for_drm_plane(plane);
>  	intel_crtc = to_intel_crtc(crtc);
>  
>  	plane->fb = state->base.fb;
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 1e22ffe..ea67093 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -803,6 +803,13 @@ intel_get_crtc_for_plane(struct drm_device *dev, int plane)
>  	return dev_priv->plane_to_crtc_mapping[plane];
>  }
>  
> +static inline struct drm_crtc *
> +intel_get_crtc_for_drm_plane(struct drm_plane *plane)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(plane->dev);
> +	return dev_priv->pipe_to_crtc_mapping[to_intel_plane(plane)->pipe];
> +}
> +
>  struct intel_unpin_work {
>  	struct work_struct work;
>  	struct drm_crtc *crtc;
> diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
> index bfe9213..2164e63 100644
> --- a/drivers/gpu/drm/i915/intel_sprite.c
> +++ b/drivers/gpu/drm/i915/intel_sprite.c
> @@ -752,7 +752,7 @@ intel_check_sprite_plane(struct drm_plane *plane,
>  	int pixel_size;
>  	int ret;
>  
> -	intel_crtc = intel_crtc ? intel_crtc : to_intel_crtc(plane->crtc);
> +	intel_crtc = to_intel_crtc(intel_get_crtc_for_drm_plane(plane));
>  	crtc_state = intel_crtc_state_for_plane(state);
>  
>  	if (!fb) {
> @@ -942,7 +942,7 @@ intel_commit_sprite_plane(struct drm_plane *plane,
>  	unsigned int crtc_w, crtc_h;
>  	uint32_t src_x, src_y, src_w, src_h;
>  
> -	crtc = crtc ? crtc : plane->crtc;
> +	crtc = intel_get_crtc_for_drm_plane(plane);
>  	intel_crtc = to_intel_crtc(crtc);
>  
>  	plane->fb = fb;
> -- 
> 1.8.5.1
> 
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-- 
Ville Syrjälä
Intel OTC
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