<div dir="auto"><div>Sorry for getting the list wrong again. Please reply to mesa-dev not dri-dev .</div><div dir="auto"> <div class="gmail_quote" dir="auto">---------- Forwarded message ---------- From: "Wladimir J. van der Laan" <<a href="mailto:laanwj@gmail.com">laanwj@gmail.com</a>> Date: Feb 3, 2017 10:56 Subject: Question about handling RGBA/BGRA in etnaviv driver To: <<a href="mailto:dri-devel@lists.freedesktop.org">dri-devel@lists.freedesktop.org</a>>, <<a href="mailto:etnaviv@lists.freedesktop.org">etnaviv@lists.freedesktop.org</a>> Cc: "Chris Healy" <<a href="mailto:cphealy@gmail.com">cphealy@gmail.com</a>> <blockquote class="quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello, With the Etnaviv driver we're running into an issue: The GPU can only render *to* BGRA formats. It can however render *from* BGRA as well as RGBA textures. I know that the OpenGL ES standard allows drivers to choose what order is most appropriate when being asked for "GL_RGBA" textures. So back when etnaviv supported only BGRA, Mesa automatically picked that and everything was okay. However a recent patch added support for RGBA formats in etnaviv_format.c. Now, Mesa creates a real GL_RGBA texture when this is requested. This is all and well for rendering, however for anything using FBO to render to textures this is a problem. Qt, for example, is assuming it can attach the GL_RGBA texture to a FBO. This fails now that GL_RGBA textures are really GL_RGBA, and it doesn't handle that error to fall back to something else so rendering issues ensue. I'm not sure how to handle this: - The quick fix would be to revert the RGBA formats patch, but the hardware supports rendering *from* RGBA textures fine so this would be throwing away a feature. - Another way would be to try to fix Qt to cope with this, and try e.g. GL_BGRA_EXT when it wants to render to a texture. Burdening the client code with this seems unintuitive to me. - Another hack would be to implement shader variants, and swap R/B in the pixel shader to emulate rendering to RGBA. Neither seems great. Does anyone have suggestions, do any of the other (gallium) drivers have this problem? Regards, Wladimir </blockquote></div> </div></div>