From: Noralf Trønnes noralf@tronnes.org
gud has a module parameter that controls whether framebuffer flushing happens synchronously during the commit or asynchronously in a worker.
GNOME before version 3.38 handled all displays in the same rendering loop. This lead to gud slowing down the refresh rate for a faster monitor. This has now been fixed so lets change the default.
The plan is to remove async flushing in the future. The code is now structured in a way that makes it easy to do this.
Link: https://blogs.gnome.org/shell-dev/2020/07/02/splitting-up-the-frame-clock/ Suggested-by: Thomas Zimmermann tzimmermann@suse.de Signed-off-by: Noralf Trønnes noralf@tronnes.org --- drivers/gpu/drm/gud/gud_pipe.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/gud/gud_pipe.c b/drivers/gpu/drm/gud/gud_pipe.c index 92189474a7ed..62c43d3632d4 100644 --- a/drivers/gpu/drm/gud/gud_pipe.c +++ b/drivers/gpu/drm/gud/gud_pipe.c @@ -25,17 +25,13 @@ #include "gud_internal.h"
/* - * Some userspace rendering loops runs all displays in the same loop. + * Some userspace rendering loops run all displays in the same loop. * This means that a fast display will have to wait for a slow one. - * For this reason gud does flushing asynchronous by default. - * The down side is that in e.g. a single display setup userspace thinks - * the display is insanely fast since the driver reports back immediately - * that the flush/pageflip is done. This wastes CPU and power. - * Such users might want to set this module parameter to false. + * Such users might want to enable this module parameter. */ -static bool gud_async_flush = true; +static bool gud_async_flush; module_param_named(async_flush, gud_async_flush, bool, 0644); -MODULE_PARM_DESC(async_flush, "Enable asynchronous flushing [default=true]"); +MODULE_PARM_DESC(async_flush, "Enable asynchronous flushing [default=0]");
/* * FIXME: The driver is probably broken on Big Endian machines.