On Thursday, July 11, 2019 11:21 AM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Tue, Jun 25, 2019 at 10:38:31PM -0300, Rodrigo Siqueira wrote: > > > The compute_crc() function is responsible for calculating the > > framebuffer CRC value; due to the XRGB format, this function has to > > ignore the alpha channel during the CRC computation. Therefore, > > compute_crc() set zero to the alpha channel directly in the input > > framebuffer, which is not a problem since this function receives a copy > > of the original buffer. However, if we want to use this function in a > > context without a buffer copy, it will change the initial value. This > > patch makes compute_crc() calculate the CRC value without modifying the > > input framebuffer. > > Uh why? For writeback we're writing the output too, so we can write > whatever we want to into the alpha channel. For writeback we should never > accept a pixel format where alpha actually matters, that doesn't make > sense. You can't see through a real screen either, they are all opaque :-) I'm not sure about that. See e.g. https://en.wikipedia.org/wiki/See-through_display Many drivers already accept FBs with alpha channels for the primary plane. https://drmdb.emersion.fr/formats?plane=1 Just making sure we aren't painting ourselves into a corner. :P _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
