Commit a0356899 authored by Noralf Trønnes's avatar Noralf Trønnes
Browse files

drm/gud: Add async_flush module parameter 



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: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: default avatarPeter Stuge <peter@stuge.se>
Link: https://patchwork.freedesktop.org/patch/msgid/20210703141321.35494-2-noralf@tronnes.org
parent b3f4ef66

drivers/gpu/drm/gud/gud_pipe.c

+15 −0
Original line number Diff line number Diff line
@@ -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)