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@xxxxxxxxxx>
Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
---
drivers/gpu/drm/mgag200/Kconfig | 12 ------------
drivers/gpu/drm/mgag200/mgag200_drv.c | 17 -----------------
drivers/gpu/drm/mgag200/mgag200_mode.c | 8 --------
3 files changed, 37 deletions(-)
diff --git a/drivers/gpu/drm/mgag200/Kconfig b/drivers/gpu/drm/mgag200/Kconfig
index 5e4d48df4854c..b28c5e4828f47 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 65f2ed18b31c5..3883f25ca4d8b 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 fc54851d3384d..d3d820f7a77d7 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>
@@ -438,13 +437,6 @@ 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
}
/*
--
2.45.0
