On Wed, Aug 24, 2016 at 08:39:52AM +0100, Chris Wilson wrote:
> When FBC is enabled, access through the fbdev is tracked using
> ORIGIN_GTT, i.e. native hw tracking by FBC. This requires the
> framebuffer to be fenced, which requires us to allocate the object
> as X-tiled.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_fbdev.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> index 8d6bfa565b50..ad3995f87485 100644
> --- a/drivers/gpu/drm/i915/intel_fbdev.c
> +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> @@ -138,14 +138,17 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
>
> mode_cmd.pitches[0] = ALIGN(mode_cmd.width *
> DIV_ROUND_UP(sizes->surface_bpp, 8), 64);
> + if (i915.enable_fbc)
> + mode_cmd.pitches[0] = ALIGN(mode_cmd.pitches[0], 512);
> +
> mode_cmd.pixel_format = drm_mode_legacy_fb_format(sizes->surface_bpp,
> sizes->surface_depth);
>
> - mutex_lock(&dev->struct_mutex);
> -
> size = mode_cmd.pitches[0] * mode_cmd.height;
> size = PAGE_ALIGN(size);
>
> + mutex_lock(&dev->struct_mutex);
> +
> /* If the FB is too big, just don't use it since fbdev is not very
> * important and we should probably use that space with FBC or other
> * features. */
> @@ -159,6 +162,12 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
> goto out;
> }
>
> + if (i915.enable_fbc) {
> + obj->tiling_and_stride = mode_cmd.pitches[0] | I915_TILING_X;
> + mode_cmd.modifier[0] = I915_FORMAT_MOD_X_TILED;
> + mode_cmd.flags |= DRM_MODE_FB_MODIFIERS;
> + }
Even more magic set-tiling calls, now also depending upon module options.
This sounds like a rather bad idea to me.
-Daniel
> +
> fb = __intel_framebuffer_create(dev, &mode_cmd, obj);
> if (IS_ERR(fb)) {
> i915_gem_object_put(obj);
> --
> 2.9.3
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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