On Wed, Aug 24, 2016 at 01:05:18PM +0200, Daniel Vetter wrote:
> 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.
FB_MODIFIERS are pretty magic, I know!
This was more of if you want to use fbdev + fbc, this is what we should
do. Note that this is not so much a module option, but fbc state. At
this point in fbdev's lifecycle, we should be able to use HAS_FBC()
which is equivalent to i915.enable_fbc once we've sanitized the options.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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