Re: [PATCH 2/2] drm/i915: Crop cursor image for CHV pipe C cursor issue

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Jun 08, 2016 at 01:57:44PM +0530, Akshu Agrawal wrote:
> CHV pipe C hits underrun when we get -ve X values of cursor. To avoid
> this we crop the cursor image for by -ve X value and thus use '0' as
> least X value.

You're talking about "-ve" here and there's absolutely no "-ve" anywhere
in your patch. That makes your commit message non-understandable.

But I think I get what you're doing here, and nope, you can't override the
cursor image like that. If we go with this w/a then you need to allocate a
new cursor gem bo instead. This is userspace-visible.

For similar reasons you're also not allowed to change crtc->state.
-Daniel

> Signed-off-by: Akshu Agrawal <akshu.agrawal@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 113 +++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h     |   3 +
>  2 files changed, 116 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index bca9245..e6e6568 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -14279,6 +14279,81 @@ void intel_create_rotation_property(struct drm_device *dev, struct intel_plane *
>  				plane->base.state->rotation);
>  }
>  
> +static void vlv_unpin_buffer_obj(struct drm_i915_gem_object *obj,
> +			  char __iomem *buffer_start)
> +{
> +	iounmap(buffer_start);
> +	i915_gem_object_ggtt_unpin(obj);
> +}
> +
> +static char __iomem *vlv_pin_and_map_buffer_obj
> +				(struct drm_i915_gem_object *obj)
> +{
> +	struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
> +	char __iomem *buffer_start;
> +	int ret;
> +
> +	ret = i915_gem_obj_ggtt_pin(obj, PAGE_SIZE, PIN_MAPPABLE);
> +	if (ret)
> +		return NULL;
> +
> +	ret = i915_gem_object_set_to_gtt_domain(obj, true);
> +	if (ret) {
> +		i915_gem_object_ggtt_unpin(obj);
> +		return NULL;
> +	}
> +
> +	buffer_start = ioremap_wc(dev_priv->gtt.mappable_base +
> +			i915_gem_obj_ggtt_offset(obj), obj->base.size);
> +	if (buffer_start == NULL) {
> +		i915_gem_object_ggtt_unpin(obj);
> +		return NULL;
> +	}
> +
> +	return buffer_start;
> +}
> +
> +static int vlv_cursor_crop(struct intel_plane_state *state,
> +				      int prev_x)
> +{
> +	struct drm_i915_gem_object *obj = intel_fb_obj(state->base.fb);
> +	struct drm_framebuffer *fb = state->base.fb;
> +	char __iomem *buffer = state->vlv_cursor_image;
> +	char __iomem *base, *cursor_base;
> +	int size = obj->base.size;
> +	int i, x = state->base.crtc_x;
> +	int bytes_per_pixel = fb->bits_per_pixel / 8;
> +
> +	base = vlv_pin_and_map_buffer_obj(obj);
> +	if (base == NULL)
> +		return -ENOMEM;
> +
> +	if (prev_x >= 0) {
> +		if (buffer != NULL)
> +			kfree(buffer);
> +		buffer = kzalloc(size, GFP_KERNEL);
> +		state->vlv_cursor_image = buffer;
> +		if (buffer == NULL)
> +			return -ENOMEM;
> +		memcpy(buffer, base, size);
> +	}
> +	cursor_base = buffer;
> +	x = -x;
> +	for (i = 0; i < state->base.crtc_h; i++) {
> +		cursor_base += x * bytes_per_pixel;
> +		memcpy(base, cursor_base,
> +			(state->base.crtc_w - x) * bytes_per_pixel);
> +		base += (state->base.crtc_w - x) * bytes_per_pixel;
> +		memset(base, 0, x * bytes_per_pixel);
> +		base += x * bytes_per_pixel;
> +		cursor_base += (state->base.crtc_w - x) * bytes_per_pixel;
> +	}
> +
> +	vlv_unpin_buffer_obj(obj, base);
> +
> +	return 0;
> +}
> +
>  static int
>  intel_check_cursor_plane(struct drm_plane *plane,
>  			 struct intel_crtc_state *crtc_state,
> @@ -14287,8 +14362,10 @@ intel_check_cursor_plane(struct drm_plane *plane,
>  	struct drm_crtc *crtc = crtc_state->base.crtc;
>  	struct drm_framebuffer *fb = state->base.fb;
>  	struct drm_i915_gem_object *obj = intel_fb_obj(fb);
> +	enum pipe pipe = to_intel_plane(plane)->pipe;
>  	unsigned stride;
>  	int ret;
> +	int crtc_prev_x = state->vlv_cursor_prev_x;
>  
>  	ret = drm_plane_helper_check_update(plane, crtc, fb, &state->src,
>  					    &state->dst, &state->clip,
> @@ -14309,6 +14386,32 @@ intel_check_cursor_plane(struct drm_plane *plane,
>  		return -EINVAL;
>  	}
>  
> +	/*
> +	 * There is an issue in CHV PIPE C where we hit underrun on
> +	 * -ve value of cursor. To avoid this we are cropping the
> +	 *  image for all PIPE C -ve values.
> +	 */
> +	if (IS_CHERRYVIEW(plane->dev)) {
> +		if (pipe == PIPE_C && state->visible &&
> +		    state->base.crtc_x < 0) {
> +			ret = vlv_cursor_crop(state, crtc_prev_x);
> +			if (ret)
> +				return -ENOMEM;
> +		} else if (crtc_prev_x < 0) { /* Restore the image back */
> +			char __iomem *base;
> +			char __iomem *org_image = state->vlv_cursor_image;
> +			int size = obj->base.size;
> +
> +			if (org_image == NULL)
> +				return -ENOMEM;
> +			base = vlv_pin_and_map_buffer_obj(obj);
> +			if (base == NULL)
> +				return -ENOMEM;
> +			memcpy(base, org_image, size);
> +			vlv_unpin_buffer_obj(obj, base);
> +		}
> +	}
> +
>  	stride = roundup_pow_of_two(state->base.crtc_w) * 4;
>  	if (obj->base.size < stride * state->base.crtc_h) {
>  		DRM_DEBUG_KMS("buffer is too small\n");
> @@ -14320,6 +14423,16 @@ intel_check_cursor_plane(struct drm_plane *plane,
>  		return -EINVAL;
>  	}
>  
> +	if (IS_CHERRYVIEW(plane->dev)) {
> +		if (pipe == PIPE_C &&
> +		    state->visible && state->base.crtc_x < 0) {
> +			state->vlv_cursor_prev_x = state->base.crtc_x;
> +			state->base.crtc_x = 0;
> +		} else {
> +			state->vlv_cursor_prev_x = state->base.crtc_x;
> +		}
> +	}
> +
>  	return 0;
>  }
>  
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index ebe7b34..0c406d1 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -350,6 +350,9 @@ struct intel_plane_state {
>  
>  	/* async flip related structures */
>  	struct drm_i915_gem_request *wait_req;
> +
> +	char __iomem *vlv_cursor_image;
> +	int vlv_cursor_prev_x;
>  };
>  
>  struct intel_initial_plane_config {
> -- 
> 1.9.1
> 
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> Intel-gfx@lists.freedesktop.org
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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