Provide a way for userspace to choose synchronous flushing/pageflips. This helps save CPU and power. It is also useful for test scripts since userspace can know when a flush has happended and wait before doing the next visual test. Cc: Peter Stuge <peter@xxxxxxxx> Cc: Linus Walleij <linus.walleij@xxxxxxxxxx> Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx> --- drivers/gpu/drm/gud/gud_pipe.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/drivers/gpu/drm/gud/gud_pipe.c b/drivers/gpu/drm/gud/gud_pipe.c index e0fb6cc969a3..8f56bf618ac2 100644 --- a/drivers/gpu/drm/gud/gud_pipe.c +++ b/drivers/gpu/drm/gud/gud_pipe.c @@ -23,6 +23,19 @@ #include "gud_internal.h" +/* + * Some userspace rendering loops runs 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. + */ +static bool gud_async_flush = true; +module_param_named(async_flush, gud_async_flush, bool, 0644); +MODULE_PARM_DESC(async_flush, "Enable asynchronous flushing [default=true]"); + /* * FIXME: The driver is probably broken on Big Endian machines. * See discussion: @@ -578,6 +591,8 @@ void gud_pipe_update(struct drm_simple_display_pipe *pipe, if (gdrm->flags & GUD_DISPLAY_FLAG_FULL_UPDATE) drm_rect_init(&damage, 0, 0, fb->width, fb->height); gud_fb_queue_damage(gdrm, fb, &damage); + if (!gud_async_flush) + flush_work(&gdrm->work); } if (!crtc->state->enable) -- 2.23.0
