diff options
| author | Jocelyn Falempe <jfalempe@redhat.com> | 2024-05-17 17:09:57 +0200 |
|---|---|---|
| committer | Jocelyn Falempe <jfalempe@redhat.com> | 2024-05-21 09:38:46 +0200 |
| commit | e7f67d0388e77e3863f2f2e9ae4a5f8bce2a718a (patch) | |
| tree | 0b83f296efb2ceec45b6f5b1a681cabf00ac0068 | |
| parent | drm/v3d: Deprecate the use of the Performance Counters enum (diff) | |
| download | linux-e7f67d0388e77e3863f2f2e9ae4a5f8bce2a718a.tar.xz linux-e7f67d0388e77e3863f2f2e9ae4a5f8bce2a718a.zip | |
Revert "drm/mgag200: Add a workaround for low-latency"
This reverts commit bfa4437fd3938ae2e186e7664b2db65bb8775670.
This workaround doesn't work reliably on all servers.
I'll replace it with an option to disable Write-Combine,
which has more impact on performance, but fix the latency
issue on all hardware.
Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240517151050.624797-2-jfalempe@redhat.com
| -rw-r--r-- | drivers/gpu/drm/mgag200/Kconfig | 12 | ||||
| -rw-r--r-- | drivers/gpu/drm/mgag200/mgag200_drv.c | 17 | ||||
| -rw-r--r-- | drivers/gpu/drm/mgag200/mgag200_mode.c | 8 |
3 files changed, 0 insertions, 37 deletions
diff --git a/drivers/gpu/drm/mgag200/Kconfig b/drivers/gpu/drm/mgag200/Kconfig index 5e4d48df4854..b28c5e4828f4 100644 --- a/drivers/gpu/drm/mgag200/Kconfig +++ b/drivers/gpu/drm/mgag200/Kconfig @@ -11,15 +11,3 @@ config DRM_MGAG200 MGA G200 desktop chips and the server variants. It requires 0.3.0 of the modesetting userspace driver, and a version of mga driver that will fail on KMS enabled devices. - -config DRM_MGAG200_IOBURST_WORKAROUND - bool "Disable buffer caching" - depends on DRM_MGAG200 && PREEMPT_RT && X86 - help - Enable a workaround to avoid I/O bursts within the mgag200 driver at - the expense of overall display performance. - It restores the <v5.10 behavior, by mapping the framebuffer in system - RAM as Write-Combining, and flushing the cache after each write. - This is only useful on x86_64 if you want to run processes with - deterministic latency. - If unsure, say N. diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.c b/drivers/gpu/drm/mgag200/mgag200_drv.c index 65f2ed18b31c..3883f25ca4d8 100644 --- a/drivers/gpu/drm/mgag200/mgag200_drv.c +++ b/drivers/gpu/drm/mgag200/mgag200_drv.c @@ -84,20 +84,6 @@ resource_size_t mgag200_probe_vram(void __iomem *mem, resource_size_t size) return offset - 65536; } -#if defined(CONFIG_DRM_MGAG200_IOBURST_WORKAROUND) -static struct drm_gem_object *mgag200_create_object(struct drm_device *dev, size_t size) -{ - struct drm_gem_shmem_object *shmem; - - shmem = kzalloc(sizeof(*shmem), GFP_KERNEL); - if (!shmem) - return NULL; - - shmem->map_wc = true; - return &shmem->base; -} -#endif - /* * DRM driver */ @@ -113,9 +99,6 @@ static const struct drm_driver mgag200_driver = { .major = DRIVER_MAJOR, .minor = DRIVER_MINOR, .patchlevel = DRIVER_PATCHLEVEL, -#if defined(CONFIG_DRM_MGAG200_IOBURST_WORKAROUND) - .gem_create_object = mgag200_create_object, -#endif DRM_GEM_SHMEM_DRIVER_OPS, }; diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c index d566e8476bf8..bb6204002cb3 100644 --- a/drivers/gpu/drm/mgag200/mgag200_mode.c +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c @@ -13,7 +13,6 @@ #include <drm/drm_atomic.h> #include <drm/drm_atomic_helper.h> -#include <drm/drm_cache.h> #include <drm/drm_damage_helper.h> #include <drm/drm_edid.h> #include <drm/drm_format_helper.h> @@ -439,13 +438,6 @@ static void mgag200_handle_damage(struct mga_device *mdev, const struct iosys_ma iosys_map_incr(&dst, drm_fb_clip_offset(fb->pitches[0], fb->format, clip)); drm_fb_memcpy(&dst, fb->pitches, vmap, fb, clip); - - /* Flushing the cache greatly improves latency on x86_64 */ -#if defined(CONFIG_DRM_MGAG200_IOBURST_WORKAROUND) - if (!vmap->is_iomem) - drm_clflush_virt_range(vmap->vaddr + clip->y1 * fb->pitches[0], - drm_rect_height(clip) * fb->pitches[0]); -#endif } /* |