kernel/linux.git/drivers/gpu/drm/drm_fbdev_dma.c, branch v6.12.80

drm/fbdev-dma: Add shadow buffering for deferred I/O

2025-07-06T09:01:49+00:00

[ Upstream commit 3603996432997f7c88da37a97062a46cda01ac9d ] DMA areas are not necessarily backed by struct page, so we cannot rely on it for deferred I/O. Allocate a shadow buffer for drivers that require deferred I/O and use it as framebuffer memory. Fixes driver errors about being "Unable to handle kernel NULL pointer dereference at virtual address" or "Unable to handle kernel paging request at virtual address". The patch splits drm_fbdev_dma_driver_fbdev_probe() in an initial allocation, which creates the DMA-backed buffer object, and a tail that sets up the fbdev data structures. There is a tail function for direct memory mappings and a tail function for deferred I/O with the shadow buffer. It is no longer possible to use deferred I/O without shadow buffer. It can be re-added if there exists a reliably test for usable struct page in the allocated DMA-backed buffer object. Signed-off-by: Thomas Zimmermann Reported-by: Nuno Gonçalves CLoses: https://lore.kernel.org/dri-devel/CAEXMXLR55DziAMbv_+2hmLeH-jP96pmit6nhs6siB22cpQFr9w@mail.gmail.com/ Tested-by: Nuno Gonçalves Fixes: 5ab91447aa13 ("drm/tiny/ili9225: Use fbdev-dma") Cc: Thomas Zimmermann Cc: # v6.11+ Reviewed-by: Simona Vetter Reviewed-by: Javier Martinez Canillas Link: https://patchwork.freedesktop.org/patch/msgid/20241211090643.74250-1-tzimmermann@suse.de Signed-off-by: Sasha Levin

drm/fbdev-dma: Support struct drm_driver.fbdev_probe

2025-05-22T12:29:53+00:00

commit 8998eedda2539d2528cfebdc7c17eed0ad35b714 upstream. Rework fbdev probing to support fbdev_probe in struct drm_driver and reimplement the old fb_probe callback on top of it. Provide an initializer macro for struct drm_driver that sets the callback according to the kernel configuration. This change allows the common fbdev client to run on top of DMA- based DRM drivers. Signed-off-by: Thomas Zimmermann Reviewed-by: Javier Martinez Canillas Link: https://patchwork.freedesktop.org/patch/msgid/20240924071734.98201-6-tzimmermann@suse.de Signed-off-by: Fabio Estevam Signed-off-by: Greg Kroah-Hartman

drm/fbdev-dma: Only cleanup deferred I/O if necessary

2024-10-10T07:49:25+00:00

Commit 5a498d4d06d6 ("drm/fbdev-dma: Only install deferred I/O if necessary") initializes deferred I/O only if it is used. drm_fbdev_dma_fb_destroy() however calls fb_deferred_io_cleanup() unconditionally with struct fb_info.fbdefio == NULL. KASAN with the out-of-tree Apple silicon display driver posts following warning from __flush_work() of a random struct work_struct instead of the expected NULL pointer derefs. [ 22.053799] ------------[ cut here ]------------ [ 22.054832] WARNING: CPU: 2 PID: 1 at kernel/workqueue.c:4177 __flush_work+0x4d8/0x580 [ 22.056597] Modules linked in: uhid bnep uinput nls_ascii ip6_tables ip_tables i2c_dev loop fuse dm_multipath nfnetlink zram hid_magicmouse btrfs xor xor_neon brcmfmac_wcc raid6_pq hci_bcm4377 bluetooth brcmfmac hid_apple brcmutil nvmem_spmi_mfd simple_mfd_spmi dockchannel_hid cfg80211 joydev regmap_spmi nvme_apple ecdh_generic ecc macsmc_hid rfkill dwc3 appledrm snd_soc_macaudio macsmc_power nvme_core apple_isp phy_apple_atc apple_sart apple_rtkit_helper apple_dockchannel tps6598x macsmc_hwmon snd_soc_cs42l84 videobuf2_v4l2 spmi_apple_controller nvmem_apple_efuses videobuf2_dma_sg apple_z2 videobuf2_memops spi_nor panel_summit videobuf2_common asahi videodev pwm_apple apple_dcp snd_soc_apple_mca apple_admac spi_apple clk_apple_nco i2c_pasemi_platform snd_pcm_dmaengine mc i2c_pasemi_core mux_core ofpart adpdrm drm_dma_helper apple_dart apple_soc_cpufreq leds_pwm phram [ 22.073768] CPU: 2 UID: 0 PID: 1 Comm: systemd-shutdow Not tainted 6.11.2-asahi+ #asahi-dev [ 22.075612] Hardware name: Apple MacBook Pro (13-inch, M2, 2022) (DT) [ 22.077032] pstate: 01400005 (nzcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) [ 22.078567] pc : __flush_work+0x4d8/0x580 [ 22.079471] lr : __flush_work+0x54/0x580 [ 22.080345] sp : ffffc000836ef820 [ 22.081089] x29: ffffc000836ef880 x28: 0000000000000000 x27: ffff80002ddb7128 [ 22.082678] x26: dfffc00000000000 x25: 1ffff000096f0c57 x24: ffffc00082d3e358 [ 22.084263] x23: ffff80004b7862b8 x22: dfffc00000000000 x21: ffff80005aa1d470 [ 22.085855] x20: ffff80004b786000 x19: ffff80004b7862a0 x18: 0000000000000000 [ 22.087439] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000005 [ 22.089030] x14: 1ffff800106ddf0a x13: 0000000000000000 x12: 0000000000000000 [ 22.090618] x11: ffffb800106ddf0f x10: dfffc00000000000 x9 : 1ffff800106ddf0e [ 22.092206] x8 : 0000000000000000 x7 : aaaaaaaaaaaaaaaa x6 : 0000000000000001 [ 22.093790] x5 : ffffc000836ef728 x4 : 0000000000000000 x3 : 0000000000000020 [ 22.095368] x2 : 0000000000000008 x1 : 00000000000000aa x0 : 0000000000000000 [ 22.096955] Call trace: [ 22.097505] __flush_work+0x4d8/0x580 [ 22.098330] flush_delayed_work+0x80/0xb8 [ 22.099231] fb_deferred_io_cleanup+0x3c/0x130 [ 22.100217] drm_fbdev_dma_fb_destroy+0x6c/0xe0 [drm_dma_helper] [ 22.101559] unregister_framebuffer+0x210/0x2f0 [ 22.102575] drm_fb_helper_unregister_info+0x48/0x60 [ 22.103683] drm_fbdev_dma_client_unregister+0x4c/0x80 [drm_dma_helper] [ 22.105147] drm_client_dev_unregister+0x1cc/0x230 [ 22.106217] drm_dev_unregister+0x58/0x570 [ 22.107125] apple_drm_unbind+0x50/0x98 [appledrm] [ 22.108199] component_del+0x1f8/0x3a8 [ 22.109042] dcp_platform_shutdown+0x24/0x38 [apple_dcp] [ 22.110357] platform_shutdown+0x70/0x90 [ 22.111219] device_shutdown+0x368/0x4d8 [ 22.112095] kernel_restart+0x6c/0x1d0 [ 22.112946] __arm64_sys_reboot+0x1c8/0x328 [ 22.113868] invoke_syscall+0x78/0x1a8 [ 22.114703] do_el0_svc+0x124/0x1a0 [ 22.115498] el0_svc+0x3c/0xe0 [ 22.116181] el0t_64_sync_handler+0x70/0xc0 [ 22.117110] el0t_64_sync+0x190/0x198 [ 22.117931] ---[ end trace 0000000000000000 ]--- Signed-off-by: Janne Grunau Fixes: 5a498d4d06d6 ("drm/fbdev-dma: Only install deferred I/O if necessary") Reviewed-by: Thomas Zimmermann Reviewed-by: Linus Walleij Signed-off-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/ZwLNuZL-8Gh5UUQb@robin

drm/fbdev-dma: Only install deferred I/O if necessary

2024-09-05T09:05:10+00:00

Deferred I/O requires struct page for framebuffer memory, which is not guaranteed for all DMA ranges. We thus only install deferred I/O if we have a framebuffer that requires it. A reported bug affected the ipu-v3 and pl111 drivers, which have video memory in either Normal or HighMem zones [ 0.000000] Zone ranges: [ 0.000000] Normal [mem 0x0000000010000000-0x000000003fffffff] [ 0.000000] HighMem [mem 0x0000000040000000-0x000000004fffffff] where deferred I/O only works correctly with HighMem. See the Closes tags for bug reports. v2: - test if screen_buffer supports deferred I/O (Sima) Signed-off-by: Thomas Zimmermann Fixes: 808a40b69468 ("drm/fbdev-dma: Implement damage handling and deferred I/O") Reported-by: Alexander Stein Closes: https://lore.kernel.org/all/23636953.6Emhk5qWAg@steina-w/ Reported-by: Linus Walleij Closes: https://lore.kernel.org/dri-devel/CACRpkdb+hb9AGavbWpY-=uQQ0apY9en_tWJioPKf_fAbXMP4Hg@mail.gmail.com/ Tested-by: Alexander Stein Tested-by: Linus Walleij Cc: Thomas Zimmermann Cc: Javier Martinez Canillas Cc: Maarten Lankhorst Cc: Maxime Ripard Reviewed-by: Simona Vetter Reviewed-by: Linus Walleij Link: https://patchwork.freedesktop.org/patch/msgid/20240904123750.31206-1-tzimmermann@suse.de

Merge tag 'drm-misc-next-fixes-2024-07-11' of https://gitlab.freedesktop.org/drm/misc/kernel into drm-next

2024-07-12T02:50:30+00:00

A fix for fbdev on big endian systems, a condition fix for a sharp panel at removal, and a fix for qxl to prevent unpinned buffer access under certain conditions. Signed-off-by: Dave Airlie From: Maxime Ripard Link: https://patchwork.freedesktop.org/patch/msgid/20240711-benign-rich-mouflon-2eeafe@houat

drm/fbdev-dma: Fix framebuffer mode for big endian devices

2024-07-08T14:28:00+00:00

The drm_mode_legacy_fb_format() function only generates formats suitable for little endian devices. switch to drm_driver_legacy_fb_format() here instead to take the device endianness into consideration, too. Suggested-by: Thomas Zimmermann Signed-off-by: Thomas Huth Reviewed-by: Thomas Zimmermann Reviewed-by: Javier Martinez Canillas Signed-off-by: Thomas Zimmermann Fixes: 6ae2ff23aa43 ("drm/client: Convert drm_client_buffer_addfb() to drm_mode_addfb2()") Cc: Geert Uytterhoeven Cc: Javier Martinez Canillas Cc: Hamza Mahfooz Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: # v6.7+ Link: https://patchwork.freedesktop.org/patch/msgid/20240702121737.522878-1-thuth@redhat.com

Merge v6.10-rc6 into drm-next

2024-07-05T08:47:28+00:00

The exynos-next pull is based on a newer -rc than drm-next. hence backmerge first to make sure the unrelated conflicts we accumulated don't end up randomly in the exynos merge pull, but are separated out. Conflicts are all benign: Adjacent changes in amdgpu and fbdev-dma code, and cherry-pick conflict in xe. Signed-off-by: Daniel Vetter

drm/fbdev-dma: Only set smem_start is enable per module option

2024-06-19T15:05:02+00:00

Only export struct fb_info.fix.smem_start if that is required by the user and the memory does not come from vmalloc(). Setting struct fb_info.fix.smem_start breaks systems where DMA memory is backed by vmalloc address space. An example error is shown below. [ 3.536043] ------------[ cut here ]------------ [ 3.540716] virt_to_phys used for non-linear address: 000000007fc4f540 (0xffff800086001000) [ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12 __virt_to_phys+0x68/0x98 [ 3.565455] Modules linked in: [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted 6.6.23-06226-g4986cc3e1b75-dirty #250 [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT) [ 3.582452] Workqueue: events_unbound deferred_probe_work_func [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 3.595233] pc : __virt_to_phys+0x68/0x98 [ 3.599246] lr : __virt_to_phys+0x68/0x98 [ 3.603276] sp : ffff800083603990 [ 3.677939] Call trace: [ 3.680393] __virt_to_phys+0x68/0x98 [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238 [ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0 [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68 [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0 [ 3.705161] drm_client_register+0x60/0xb0 [ 3.709269] drm_fbdev_dma_setup+0x94/0x148 Additionally, DMA memory is assumed to by contiguous in physical address space, which is not guaranteed by vmalloc(). Resolve this by checking the module flag drm_leak_fbdev_smem when DRM allocated the instance of struct fb_info. Fbdev-dma then only sets smem_start only if required (via FBINFO_HIDE_SMEM_START). Also guarantee that the framebuffer is not located in vmalloc address space. Signed-off-by: Thomas Zimmermann Reported-by: Peng Fan (OSS) Closes: https://lore.kernel.org/dri-devel/20240604080328.4024838-1-peng.fan@oss.nxp.com/ Reported-by: Geert Uytterhoeven Closes: https://lore.kernel.org/dri-devel/CAMuHMdX3N0szUvt1VTbroa2zrT1Nye_VzPb5qqCZ7z5gSm7HGw@mail.gmail.com/ Fixes: a51c7663f144 ("drm/fb-helper: Consolidate CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM") Tested-by: Geert Uytterhoeven Reviewed-by: Daniel Vetter Cc: # v6.4+ Link: https://patchwork.freedesktop.org/patch/msgid/20240617152843.11886-1-tzimmermann@suse.de

drm/fbdev-dma: Clean up deferred I/O

2024-05-15T12:50:20+00:00

Call fb_deferred_io_cleanup() upon destroying the framebuffer device. Releases the internal memory. Signed-off-by: Thomas Zimmermann Fixes: 808a40b69468 ("drm/fbdev-dma: Implement damage handling and deferred I/O") Cc: Thomas Zimmermann Cc: Javier Martinez Canillas Cc: Maarten Lankhorst Cc: Maxime Ripard Reviewed-by: Javier Martinez Canillas Link: https://patchwork.freedesktop.org/patch/msgid/20240507145529.31368-1-tzimmermann@suse.de

drm/fbdev-dma: Implement damage handling and deferred I/O

2024-05-02T09:33:22+00:00

Add support for damage handling and deferred I/O to fbdev-dma. This enables fbdev-dma to support all DMA-memory-based DRM drivers, even such with a dirty callback in their framebuffers. The patch adds the code for deferred I/O and also sets a dedicated helper for struct fb_ops.fb_mmap that support coherent mappings. v3: - init fb_ops with FB_GEN_DEFAULT_DEFERRED_DMAMEM_OPS() (Javier) Signed-off-by: Thomas Zimmermann Reviewed-by: Javier Martinez Canillas Link: https://patchwork.freedesktop.org/patch/msgid/20240419083331.7761-22-tzimmermann@suse.de