https://bugs.freedesktop.org/show_bug.cgi?id=45558
Bug #: 45558 Summary: cannot render on a drawable of size equal the max framebuffer size Classification: Unclassified Product: Mesa Version: git Platform: All OS/Version: All Status: NEW Severity: normal Priority: medium Component: Drivers/DRI/i830 AssignedTo: dri-devel@lists.freedesktop.org ReportedBy: prahal@yahoo.com
Created attachment 56550 --> https://bugs.freedesktop.org/attachment.cgi?id=56550 do not drift one pixel above what we want - x2, y2 are exclusive max
The xorg drawable sizes are exclusive as I have learned on xorg-devel irc channel by MrCooper. This means that width = x2 - x1 , x2 behing exclusive and thus in the places the code does DrawBuffer->Width + x1 to get the right coordinate when we get a coordinate one pixel above what we want (ie we send x2 which is exclusive).
This patch fixes a few places were the gen2 865g are affected by this bug. That is gnome-shell renders badly due to cogl using atlas a power of two of the resolution (which is good but this leads to 2048 which is the framebuffer max size on gen2).
I will also attach the testcase I used which is dumb but reproduce the same issue as gnome-shell /cogl. Ie a drawable attached to the context as read and draw buffer the size equal to framebuffer max size , ie 2048, on 865g gen2.