We've had reports about performance regressions after switching mgag200 from VRAM helpers to SHMEM helpers. SHMEM pages use writecombine caching by default, but can also use the platform's default page caching. Doing so improves the performance of I/O on the framebuffer.
Mgag200's hardware does not access framebuffer pages directly (i.e., via DMA), so enabling caching does not have an effect on consistency of the framebuffer memory or the displayed data. Signed-off-by: Thomas Zimmermann <[email protected]> Fixes: 913ec479bb5c ("drm/mgag200: Replace VRAM helpers with SHMEM helpers") Cc: Thomas Zimmermann <[email protected]> Cc: Emil Velikov <[email protected]> Cc: Dave Airlie <[email protected]> Cc: Daniel Vetter <[email protected]> Cc: Krzysztof Kozlowski <[email protected]> Cc: Gerd Hoffmann <[email protected]> Cc: Sam Ravnborg <[email protected]> Cc: Rong Chen <[email protected]> Cc: John Donnelly <[email protected]> Link: https://lore.kernel.org/dri-devel/20200617092252.GA5279@shao2-debian/ --- drivers/gpu/drm/mgag200/mgag200_drv.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.c b/drivers/gpu/drm/mgag200/mgag200_drv.c index e19660f4a637..7189c7745baf 100644 --- a/drivers/gpu/drm/mgag200/mgag200_drv.c +++ b/drivers/gpu/drm/mgag200/mgag200_drv.c @@ -36,6 +36,7 @@ static struct drm_driver mgag200_driver = { .major = DRIVER_MAJOR, .minor = DRIVER_MINOR, .patchlevel = DRIVER_PATCHLEVEL, + .gem_create_object = drm_gem_shmem_create_object_cached, DRM_GEM_SHMEM_DRIVER_OPS, }; -- 2.27.0 _______________________________________________ dri-devel mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/dri-devel
