56 lines
2.2 KiB
Diff
56 lines
2.2 KiB
Diff
From e0eb7ca2dd07ca8878b67cc20e75f9d7e46d80f4 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
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Date: Sat, 3 Jul 2021 16:13:21 +0200
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Subject: [PATCH] drm/gud: Add async_flush module parameter
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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[ drm-misc commit a0356899ebe8ecde0da9c5685cc47154db973a5e ]
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Provide a way for userspace to choose synchronous flushing/pageflips.
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This helps save CPU and power.
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It is also useful for test scripts since userspace can know when a flush
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has happended and wait before doing the next visual test.
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Cc: Linus Walleij <linus.walleij@linaro.org>
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Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
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Reviewed-by: Peter Stuge <peter@stuge.se>
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Link: https://patchwork.freedesktop.org/patch/msgid/20210703141321.35494-2-noralf@tronnes.org
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---
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drivers/gpu/drm/gud/gud_pipe.c | 15 +++++++++++++++
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1 file changed, 15 insertions(+)
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--- a/drivers/gpu/drm/gud/gud_pipe.c
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+++ b/drivers/gpu/drm/gud/gud_pipe.c
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@@ -24,6 +24,19 @@
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#include "gud_internal.h"
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/*
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+ * Some userspace rendering loops runs all displays in the same loop.
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+ * This means that a fast display will have to wait for a slow one.
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+ * For this reason gud does flushing asynchronous by default.
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+ * The down side is that in e.g. a single display setup userspace thinks
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+ * the display is insanely fast since the driver reports back immediately
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+ * that the flush/pageflip is done. This wastes CPU and power.
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+ * Such users might want to set this module parameter to false.
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+ */
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+static bool gud_async_flush = true;
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+module_param_named(async_flush, gud_async_flush, bool, 0644);
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+MODULE_PARM_DESC(async_flush, "Enable asynchronous flushing [default=true]");
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+
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+/*
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* FIXME: The driver is probably broken on Big Endian machines.
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* See discussion:
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* https://lore.kernel.org/dri-devel/CAKb7UvihLX0hgBOP3VBG7O+atwZcUVCPVuBdfmDMpg0NjXe-cQ@mail.gmail.com/
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@@ -577,6 +590,8 @@ void gud_pipe_update(struct drm_simple_d
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if (gdrm->flags & GUD_DISPLAY_FLAG_FULL_UPDATE)
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drm_rect_init(&damage, 0, 0, fb->width, fb->height);
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gud_fb_queue_damage(gdrm, fb, &damage);
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+ if (!gud_async_flush)
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+ flush_work(&gdrm->work);
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}
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if (!crtc->state->enable)
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