This is a rebase of Alexander Graf's video damage tracking series, with some tests and other changes. The original cover letter is as follows:
> This patch set speeds up graphics output on ARM by a factor of 60x. > > On most ARM SBCs, we keep the frame buffer in DRAM and map it as cached, > but need it accessible by the display controller which reads directly > from a later point of consistency. Hence, we flush the frame buffer to > DRAM on every change. The full frame buffer. > > Unfortunately, with the advent of 4k displays, we are seeing frame buffers > that can take a while to flush out. This was reported by Da Xue with grub, > which happily print 1000s of spaces on the screen to draw a menu. Every > printed space triggers a cache flush. > > This patch set implements the easiest mitigation against this problem: > Damage tracking. We remember the lowest common denominator region that was > touched since the last video_sync() call and only flush that. The most > typical writer to the frame buffer is the video console, which always > writes rectangles of characters on the screen and syncs afterwards. > > With this patch set applied, we reduce drawing a large grub menu (with > serial console attached for size information) on an RK3399-ROC system > at 1440p from 55 seconds to less than 1 second. > > Version 2 also implements VIDEO_COPY using this mechanism, reducing its > overhead compared to before as well. So even x86 systems should be faster > with this now :). > > > Alternatives considered: > > 1) Lazy sync - Sandbox does this. It only calls video_sync(true) ever > so often. We are missing timers to do this generically. > > 2) Double buffering - We could try to identify whether anything changed > at all and only draw to the FB if it did. That would require > maintaining a second buffer that we need to scan. > > 3) Text buffer - Maintain a buffer of all text printed on the screen with > respective location. Don't write if the old and new character are > identical. This would limit applicability to text only and is an > optimization on top of this patch set. > > 4) Hash screen lines - Create a hash (sha256?) over every line when it > changes. Only flush when it does. I'm not sure if this would waste > more time, memory and cache than the current approach. It would make > full screen updates much more expensive. Changes in v5: - Add patch "video: test: Split copy frame buffer check into a function" - Add patch "video: test: Support checking copy frame buffer contents" - Add patch "video: test: Test partial updates of hardware frame buffer" - Use xstart, ystart, xend, yend as names for damage region - Document damage struct and fields in struct video_priv comment - Return void from video_damage() - Fix undeclared priv error in video_sync() - Drop unused headers from video-uclass.c - Use IS_ENABLED() instead of CONFIG_IS_ENABLED() - Call video_damage() also in video_fill_part() - Use met->baseline instead of priv->baseline - Use fontdata->height/width instead of VIDEO_FONT_HEIGHT/WIDTH - Update console_rotate.c video_damage() calls to pass video tests - Remove mention about not having minimal damage for console_rotate.c - Add patch "video: test: Test video damage tracking via vidconsole" - Document new vdev field in struct efi_gop_obj comment - Remove video_sync_copy() also from video_fill(), video_fill_part() - Fix memmove() calls by removing the extra dev argument - Call video_sync() before checking copy_fb in video tests - Imply VIDEO_DAMAGE for video drivers instead of selecting it - Imply VIDEO_DAMAGE also for VIDEO_TIDSS v4: https://lore.kernel.org/all/20230103215004.22646-1-ag...@csgraf.de/ Changes in v4: - Move damage clear to patch "dm: video: Add damage tracking API" - Simplify first damage logic - Remove VIDEO_DAMAGE default for ARM - Skip damage on EfiBltVideoToBltBuffer - Add patch "video: Always compile cache flushing code" - Add patch "video: Enable VIDEO_DAMAGE for drivers that need it" v3: https://lore.kernel.org/all/20221230195828.88134-1-ag...@csgraf.de/ Changes in v3: - Adapt to always assume DM is used - Adapt to always assume DM is used - Make VIDEO_COPY always select VIDEO_DAMAGE v2: https://lore.kernel.org/all/20220609225921.62462-1-ag...@csgraf.de/ Changes in v2: - Remove ifdefs - Fix ranges in truetype target - Limit rotate to necessary damage - Remove ifdefs from gop - Fix dcache range; we were flushing too much before - Add patch "video: Use VIDEO_DAMAGE for VIDEO_COPY" v1: https://lore.kernel.org/all/20220606234336.5021-1-ag...@csgraf.de/ Alexander Graf (9): dm: video: Add damage tracking API dm: video: Add damage notification on display fills vidconsole: Add damage notifications to all vidconsole drivers video: Add damage notification on bmp display efi_loader: GOP: Add damage notification on BLT video: Only dcache flush damaged lines video: Use VIDEO_DAMAGE for VIDEO_COPY video: Always compile cache flushing code video: Enable VIDEO_DAMAGE for drivers that need it Alper Nebi Yasak (4): video: test: Split copy frame buffer check into a function video: test: Support checking copy frame buffer contents video: test: Test partial updates of hardware frame buffer video: test: Test video damage tracking via vidconsole arch/arm/mach-omap2/omap3/Kconfig | 1 + arch/arm/mach-sunxi/Kconfig | 1 + drivers/video/Kconfig | 26 +++ drivers/video/console_normal.c | 27 ++-- drivers/video/console_rotate.c | 94 +++++++---- drivers/video/console_truetype.c | 37 +++-- drivers/video/exynos/Kconfig | 1 + drivers/video/imx/Kconfig | 1 + drivers/video/meson/Kconfig | 1 + drivers/video/rockchip/Kconfig | 1 + drivers/video/stm32/Kconfig | 1 + drivers/video/tegra20/Kconfig | 1 + drivers/video/tidss/Kconfig | 1 + drivers/video/vidconsole-uclass.c | 16 -- drivers/video/video-uclass.c | 190 ++++++++++++---------- drivers/video/video_bmp.c | 7 +- include/video.h | 59 +++---- include/video_console.h | 52 ------ lib/efi_loader/efi_gop.c | 7 + test/dm/video.c | 256 ++++++++++++++++++++++++------ 20 files changed, 483 insertions(+), 297 deletions(-) base-commit: 3881c9fbb7fdd98f6eae5cd33f7e9abe9455a585 -- 2.40.1
