> -----Original Message----- > From: Ville Syrjälä [mailto:ville.syrjala@xxxxxxxxxxxxxxx] > Sent: Wednesday, September 09, 2015 11:06 AM > To: Konduru, Chandra > Cc: Syrjala, Ville; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Vetter, Daniel > Subject: Re: [PATCH 11/15] drm/i915: Add NV12 to primary plane > programming. > > On Wed, Sep 09, 2015 at 05:12:06PM +0000, Konduru, Chandra wrote: > > > > > > > > + /* For tile-Yf, uv-subplane tile width is 2x of Y- > > > subplane > > > > > > > */ > > > > > > > > + aux_stride = fb->modifier[0] == > > > > > > > I915_FORMAT_MOD_Yf_TILED ? > > > > > > > > + stride / 2 : stride; > > > > > > > > > > > > > > The 2x part was rather well hidden in the spec. How do we deal with > > > > > > > cases when the Y stride is an odd number of tiles? > > > > > > > > > > > > It should be a round up division to take care of that scenario. > > > > > > > > > > That would stil lresult in a corrupted picture I think. So I was > > > > > thinking that we should just refuse to create NCV12 framebuffers with a > > > > > poorly aligned stride. > > > > > > > > > I added a check in intel_framebuffer_init() which should catch them: > > > > if (mode_cmd->pitches[0] != mode_cmd->pitches[1]) { > > > > DRM_DEBUG("y and uv subplanes have different pitches\n"); > > > > return -EINVAL; > > > > } > > > > > > That won't catch the case I'm worried about. We would also need to make > > > sure pitches[1] is aligned to the UV tile width. > > > > If caller is following tile/row/pitch alignments properly for sub-planes of > > NV12 Yf buffer, above check will catch. > > But are you referring a case where userland isn't following tile/row size > > alignments properly? In that case, above may not catch. But > > isn't that is the case even with other FB formats if user land not > > following tile/row/pitch alignments? > > We reject any attempt to create a framebuffer with a poorly aligned > stride. > > Hmm. Actually I suppose we should just handle it in > intel_fb_stride_alignment(). Eg.: > > case Yf: > if (cpp != 1 || pixel_format == DRM_FORMAT_NV12) > return 128; > else > return 64; This check is already there in intel_fb_stride_alignment() which is called from intel_framebuffer_init(). But it always does for 1st sub-plane which means does for Y. It needs an update to pass a sub-plane (for UV) parameter, and made another call for UV-plane alignment check. Will this be ok? > > -- > Ville Syrjälä > Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
