(was: drm/vram-helper: Fix performance regression in fbdev) Generic fbdev emulation maps and unmaps the console BO for updating it's content from the shadow buffer. If this involves an actual mapping operation (instead of reusing an existing mapping), lots of debug messages may be printed, such as x86/PAT: Overlap at 0xd0000000-0xd1000000 x86/PAT: reserve_memtype added [mem 0xd0000000-0xd02fffff], track write-combining, req write-combining, ret write-combining x86/PAT: free_memtype request [mem 0xd0000000-0xd02fffff] as reported at [1]. Drivers using VRAM helpers may also see reduced performance as the mapping operations can create overhead. This patch set fixes the problem by adding a ref counter to the GEM VRAM buffers' kmap operation, and keeping the fbdev's console buffer mapped while the console is being displayed. These changes avoid the frequent mappings in the fbdev code. The drivers, ast and mgag200, map the console's buffer when it becomes visible and the fbdev code reuses this mapping. The original fbdev code in ast and mgag200 used the same strategy. [1] https://lists.freedesktop.org/archives/dri-devel/2019-September/234308.html v2: * fixed comment typos Thomas Zimmermann (3): drm/vram: Add kmap ref-counting to GEM VRAM objects drm/ast: Map fbdev framebuffer while it's being displayed drm/mgag200: Map fbdev framebuffer while it's being displayed drivers/gpu/drm/ast/ast_mode.c | 19 +++++++ drivers/gpu/drm/drm_gem_vram_helper.c | 74 +++++++++++++++++++------- drivers/gpu/drm/mgag200/mgag200_mode.c | 20 +++++++ include/drm/drm_gem_vram_helper.h | 19 +++++++ 4 files changed, 114 insertions(+), 18 deletions(-) -- 2.23.0 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
