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Jocelyn Falempe bfa4437fd3 drm/mgag200: Add a workaround for low-latency 
We found a regression in v5.10 on real-time server, using the
rt-kernel and the mgag200 driver. It's some really specialized
workload, with <10us latency expectation on isolated core.
After the v5.10, the real time tasks missed their <10us latency
when something prints on the screen (fbcon or printk)

The regression has been bisected to 2 commits:
commit 0b34d58b6c ("drm/mgag200: Enable caching for SHMEM pages")
commit 4862ffaec5 ("drm/mgag200: Move vmap out of commit tail")

The first one changed the system memory framebuffer from Write-Combine
to the default caching.
Before the second commit, the mgag200 driver used to unmap the
framebuffer after each frame, which implicitly does a cache flush.
Both regressions are fixed by this commit, which restore WC mapping
for the framebuffer in system memory, and add a cache flush.
This is only needed on x86_64, for low-latency workload,
so the new kconfig DRM_MGAG200_IOBURST_WORKAROUND depends on
PREEMPT_RT and X86.

For more context, the whole thread can be found here [1]

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/dri-devel/20231019135655.313759-1-jfalempe@redhat.com/ # 1
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240208095125.377908-1-jfalempe@redhat.com
 		2024-02-26 16:37:51 +01:00
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amd Linux 6.8-rc6 2024-02-26 11:41:07 +01:00
arm
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armada
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aspeed
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ast This cycle, I2C removes the currently unused CLASS_DDC support 2024-01-18 17:29:01 -08:00
atmel-hlcdc
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bridge drm/bridge: adv7511: fix crash on irq during probe 2024-02-21 16:29:58 +01:00
ci drm/ci: mark universal-plane-sanity as failing on SC7180 2024-02-19 17:31:18 -03:00
display drm/dp: add an API to indicate if sink supports VSC SDP 2024-02-22 22:47:29 +02:00
etnaviv
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exynos Several fixups 2024-01-25 14:22:15 +10:00
fsl-dcu
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gma500 drm: remove I2C_CLASS_DDC support 2024-01-18 21:10:41 +01:00
gud
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hisilicon drm-misc-next for v6.9: 2024-02-05 13:50:15 +10:00
hyperv drm/hyperv: Remove firmware framebuffers with aperture helper 2024-01-12 12:38:37 +01:00
i2c
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i915 Merge drm/drm-next into drm-misc-next 2024-02-26 14:20:50 +01:00
imagination One fix for drm/plane to avoid a use-after-free and some additional 2024-01-05 10:31:54 +10:00
imx drm/imx/dcss: have all init functions use devres 2024-02-02 15:36:21 +02:00
ingenic drm: Clean-up superfluously selecting VT_HW_CONSOLE_BINDING 2024-01-12 13:58:20 +01:00
kmb
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lib
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lima drm/lima: standardize debug messages by ip name 2024-02-12 16:27:48 +08:00
logicvc
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loongson Merge drm/drm-next into drm-misc-next 2024-01-29 14:20:23 +01:00
mcde drm: Clean-up superfluously selecting VT_HW_CONSOLE_BINDING 2024-01-12 13:58:20 +01:00
mediatek drm/mediatek/hdmi: switch to ->edid_read callback 2024-02-09 10:15:52 +02:00
meson Linux 6.8-rc6 2024-02-26 11:41:07 +01:00
mgag200 drm/mgag200: Add a workaround for low-latency 2024-02-26 16:37:51 +01:00
msm Linux 6.8-rc6 2024-02-26 11:41:07 +01:00
mxsfb drm: lcdif: Switch to drmm_mode_config_init 2024-02-26 08:33:45 +01:00
nouveau Linux 6.8-rc6 2024-02-26 11:41:07 +01:00
omapdrm drm/omap/hdmi5: switch to ->edid_read callback 2024-02-09 10:16:01 +02:00
panel drm/panel: simple: Add BOE BP082WX1-100 8.2" panel 2024-02-19 12:38:46 +01:00
panfrost
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pl111 drm: Clean-up superfluously selecting VT_HW_CONSOLE_BINDING 2024-01-12 13:58:20 +01:00
qxl drm/ttm: replace busy placement with flags v6 2024-01-25 09:59:44 +01:00
radeon amd-drm-next-6.9-2024-02-19: 2024-02-22 13:21:19 +10:00
renesas drm: renesas: rz-du: Fix redefinition errors related to rzg2l_du_vsp_*() 2024-02-22 14:46:41 +01:00
rockchip Linux 6.8-rc6 2024-02-26 11:41:07 +01:00
scheduler Linux 6.8-rc6 2024-02-26 11:41:07 +01:00
solomon drm-misc-next for v6.9: 2024-02-05 13:50:15 +10:00
sprd
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sti
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stm
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sun4i drm/sun4i: hdmi: Consolidate atomic_check and mode_valid 2024-02-26 10:33:18 +01:00
tegra drm/tegra: put drm_gem_object ref on error in tegra_fb_create 2024-02-22 18:29:22 +01:00
tests Linux 6.8-rc6 2024-02-26 11:41:07 +01:00
tidss drm/tidss: Fix sync-lost issue with two displays 2024-02-26 10:09:43 +02:00
tilcdc drm/tilcdc: request and mapp iomem with devres 2023-12-28 19:29:04 +02:00
tiny
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ttm Linux 6.8-rc6 2024-02-26 11:41:07 +01:00
tve200 drm: Clean-up superfluously selecting VT_HW_CONSOLE_BINDING 2024-01-12 13:58:20 +01:00
udl
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v3d drm/v3d: Enable V3D to use different PAGE_SIZE 2024-02-23 16:37:20 -03:00
vboxvideo
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vc4 drm-misc-next for v6.9: 2024-02-05 13:50:15 +10:00
vgem
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virtio drm-misc-next for v6.9: 2024-02-05 13:50:15 +10:00
vkms drm/vkms: Avoid reading beyond LUT array 2024-01-02 12:06:53 -01:00
vmwgfx drm/vmwgfx: Fix the lifetime of the bo cursor memory 2024-01-30 14:18:21 -05:00
xe drm/xe feature pull for v6.9: 2024-02-26 10:49:10 +01:00
xen
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xlnx drm: xlnx: zynqmp_dpsub: switch to ->edid_read callback 2024-02-09 10:16:03 +02:00
Kconfig drm-misc-next for v6.9: 2024-02-05 13:50:15 +10:00
Makefile
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drm_aperture.c
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drm_atomic.c
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drm_atomic_helper.c
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drm_atomic_state_helper.c
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drm_atomic_uapi.c
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drm_auth.c drm-next for 6.8: 2024-01-12 11:32:19 -08:00
drm_blend.c
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drm_bridge.c drm/bridge: remove ->get_edid callback 2024-02-09 10:16:20 +02:00
drm_bridge_connector.c drm/bridge: switch to drm_bridge_edid_read() 2024-02-08 17:10:44 +02:00
drm_buddy.c drm/buddy: Modify duplicate list_splice_tail call 2024-02-16 13:03:14 +01:00
drm_cache.c
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drm_client.c
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drm_client_modeset.c
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drm_color_mgmt.c
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drm_connector.c
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drm_crtc.c Linux 6.8-rc6 2024-02-26 11:41:07 +01:00
drm_crtc_helper.c
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drm_crtc_helper_internal.h
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drm_crtc_internal.h
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drm_damage_helper.c
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drm_debugfs.c drm/debugfs: drop unneeded DEBUG_FS guard 2024-01-02 15:50:13 +02:00
drm_debugfs_crc.c
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drm_displayid.c
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drm_drv.c
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drm_dumb_buffers.c
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drm_edid.c drm-misc-next for v6.9: 2024-02-05 13:50:15 +10:00
drm_edid_load.c drm/edid/firmware: Remove built-in EDIDs 2024-02-26 14:05:18 +01:00
drm_eld.c
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drm_encoder.c
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drm_encoder_slave.c
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drm_exec.c Merge drm/drm-next into drm-misc-next 2024-01-29 14:20:23 +01:00
drm_fb_dma_helper.c
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drm_fb_helper.c
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drm_fbdev_dma.c
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drm_fbdev_generic.c
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drm_file.c drm: update drm_show_memory_stats() for dma-bufs 2024-02-16 12:52:50 +01:00
drm_flip_work.c
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drm_format_helper.c
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drm_fourcc.c
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drm_framebuffer.c drm: Warn when freeing a framebuffer that's still on a list 2023-12-23 07:31:29 +02:00
drm_gem.c
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drm_gem_atomic_helper.c
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drm_gem_dma_helper.c
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drm_gem_framebuffer_helper.c
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drm_gem_shmem_helper.c
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drm_gem_ttm_helper.c
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drm_gem_vram_helper.c drm/ttm: replace busy placement with flags v6 2024-01-25 09:59:44 +01:00
drm_gpuvm.c
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drm_internal.h
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drm_ioc32.c
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drm_ioctl.c
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drm_kms_helper_common.c
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drm_lease.c
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drm_managed.c drm/managed: Add drmm_release_action 2024-01-17 10:38:39 +01:00
drm_mipi_dbi.c
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drm_mipi_dsi.c drm: mipi-dsi: make mipi_dsi_bus_type const 2024-02-07 12:35:10 +02:00
drm_mm.c
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drm_mode_config.c drm/mode: switch from drm_debug_printer() to device specific drm_dbg_printer() 2024-02-09 11:51:59 +02:00
drm_mode_object.c
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drm_modes.c drm-misc-next for v6.9: 2024-02-05 13:50:15 +10:00
drm_modeset_helper.c
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drm_modeset_lock.c drm: remove drm_debug_printer in favor of drm_dbg_printer 2024-02-09 11:52:43 +02:00
drm_of.c
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drm_panel.c
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drm_panel_orientation_quirks.c drm: panel-orientation-quirks: Add quirk for GPD Win Mini 2024-01-19 09:25:22 +01:00
drm_pci.c
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drm_plane.c drm: Don't unref the same fb many times by mistake due to deadlock handling 2023-12-23 07:31:05 +02:00
drm_plane_helper.c
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drm_prime.c drm/prime: Support page array >= 4GB 2024-02-13 16:36:04 +01:00
drm_print.c drm: remove drm_debug_printer in favor of drm_dbg_printer 2024-02-09 11:52:43 +02:00
drm_privacy_screen.c
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drm_privacy_screen_x86.c
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drm_probe_helper.c drm/probe-helper: remove unused drm_connector_helper_get_modes_from_ddc() 2024-01-08 12:37:52 +02:00
drm_property.c
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drm_rect.c
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drm_self_refresh_helper.c
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drm_simple_kms_helper.c
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drm_suballoc.c
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drm_syncobj.c Linux 6.8-rc6 2024-02-26 11:41:07 +01:00
drm_sysfs.c
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drm_trace.h
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drm_trace_points.c
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drm_vblank.c
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drm_vblank_work.c
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drm_vma_manager.c
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drm_writeback.c
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