On Thu, Aug 23, 2018 at 6:14 AM, John Stultz <john.stultz@xxxxxxxxxx> wrote: > On Mon, Aug 20, 2018 at 11:44 PM, John Stultz <john.stultz@xxxxxxxxxx> wrote: >> Hey Noralf, all, >> I've been digging for a bit on the regression that this patch has >> tripped on the HiKey board as reported here: >> https://lkml.org/lkml/2018/8/16/81 >> >> The first issue was that the kirin driver was setting >> mode_config.max_width/height = 2048, which was causing errors as the >> the requested resolution was 1920x2160 (due to surfaceflinger >> requesting y*2 for page flipping). > > Hey Noralf, > Sorry, I know your probably sick of me. But I just wanted to circle > around on this little bit. So part of the issue I found earlier, was > that I'm running w/ CONFIG_DRM_FBDEV_OVERALLOC=200, to support > Surfaceflinger's request for page flipping. This is what makes the Y > resolution 2160, which runs afoul of the new max_height check of 2048 > in the generic code. > > I was checking with Xinliang, who know the kirin display hardware, > about the max_height being set to 2048 to ensure bumping it up wasn't > a problem, but he said 2048x2048 was unfortunately not arbitrary, and > that was the hard limit of the display hardware. However, with > overalloc, the 1920x2160 res fbdev should still be ok, as only > 1920x1080 is actually displayed at one time. > > So it seems like we might need to multiply the max_height by the > overalloc factor when we are checking it in > drm_internal_framebuffer_create? > > Does that approach sound sane, or would folks prefer something different? I guess we could simply not check against the height limit when allocating framebuffers. But we've done that for userspace buffers since forever (they just allocate 2 buffers for page-flipping), so I have no idea what would all break if we'd suddenly lift this restriction. And whether we'd lift it for fbdev only or for everyone doesn't really make much of a difference, since either this works, or it doesn't (across all chips). -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
