Add a debugfs file under the client directory which shares
the root page table base address of the VM.
This address could be used to dump the pagetable for debug
memory issues.
Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20250704075548.1549849-4-sunil.khatri@amd.com
Signed-off-by: Christian König <christian.koenig@amd.com>
add support to add a directory for each client-id
with root at the dri level. Since the clients are
unique and not just related to one single drm device,
so it makes more sense to add all the client based
nodes with root as dri.
Also create a debugfs file which show the process
information for the client and create a symlink back
to the parent drm device from each client.
Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20250704075548.1549849-3-sunil.khatri@amd.com
Signed-off-by: Christian König <christian.koenig@amd.com>
Requirement is to create per client-id based directories to
hold key debugging information and for that access to
root debugfs dentry is need which is not in one place
and that information cannot be stored in drm_device.
Move the debugfs functionality from drm_drv.c and drm_accel.c
to drm_debugfs.c This enables debugfs root node reference
directly drm_debugfs.c and hence enable to create per client-id
directory.
v8: Create drm_accel dentry only if it's config is enabled (Jeff, Hugo)
v8: Merge drm_drv and drm_accel debugfs patches (Koenig, Christian)
v10: Since we moved drm_debugfs_root, hence to handle drm bridge
debugfs add a new function which call drm_bridge_debugfs_params where
drm_debugfs_root is accessible.
Suggested-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>
Link: https://lore.kernel.org/r/20250704075548.1549849-2-sunil.khatri@amd.com
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Move work queue allocation into a helper for a more streamlined function
body.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Philipp Stanner <phasta@kernel.org>
Reviewed-by: Maíra Canal <mcanal@igalia.com>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Link: https://lore.kernel.org/r/20250704130754.89935-1-tvrtko.ursulin@igalia.com
Rather than returning ERR_PTR or NULL on failure, replace the NULL
return with ERR_PTR(-ENOMEM). This simplifies error handling at the
caller. While here, add kernel documentation for
drmm_alloc_ordered_workqueue.
Cc: Louis Chauvet <louis.chauvet@bootlin.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Link: https://lore.kernel.org/r/20250702232831.3271328-2-matthew.brost@intel.com
Documentation for luminance_set for struct drm_edp_backlight_info
was missed which causes warnings.
Fixes: 2af612ad42 ("drm/dp: Introduce new member in drm_backlight_info")
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@gmail.com>
Link: https://lore.kernel.org/r/20250701085054.746408-1-suraj.kandpal@intel.com
Drop the unused MIPI_DSI_MODE_VSYNC_FLUSH flag. Whether or not a display
FIFO flush on vsync is required to avoid sending garbage to the panel is
not a property of the DSI link, but of the integration between display
controller and DSI host bridge.
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250627-dsi-vsync-flush-v2-4-4066899a5608@pengutronix.de
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Drop the MIPI_DSI_MODE_VSYNC_FLUSH flag from DSI mode_flags.
It has no effect anymore.
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250627-dsi-vsync-flush-v2-3-4066899a5608@pengutronix.de
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Drop the MIPI_DSI_MODE_VSYNC_FLUSH flag from DSI mode_flags.
It has no effect anymore.
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250627-dsi-vsync-flush-v2-2-4066899a5608@pengutronix.de
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Always flush the display FIFO on vsync pulse, even if not explicitly
requested by the panel via MIPI_DSI_MODE_VSYNC_FLUSH mode_flag.
The display FIFO should be empty at vsync. Flushing it at vsync pulses
helps to remove garbage that may have entered the FIFO during startup
(if synchronisation between upstream display controller and Samsung DSIM
is lacking) and that may persist in form of last frame's leftovers on
subsequent frames. Flushing the display FIFO if it is already empty
should have no effect.
This will allow to remove the MIPI_DSI_MODE_VSYNC_FLUSH flag, which is
only used by the Samsung DSIM bridge driver. Arguably this flag doesn't
belong in the panel configuration at all: flushing the display FIFO on
vsync is a workaround for issues with the integration between display
controller and DSI bridge, not a property of the DSI link between bridge
and panel. No panel actually has a requirement to receive garbage or old
frame content after vsync.
I wonder if host controller FIFO resets are mentioned by the MIPI DSI
specification at all. This patch is based on the assumption that the
MIPI_DSI_MODE_VSYNC_FLUSH flag only exists because the DSIM_MFLUSH_VS
bit happens to be located in the same register as the bits controlling
the DSI mode.
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20250627-dsi-vsync-flush-v2-1-4066899a5608@pengutronix.de
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
panthor_gpu_block_power_on() takes a register offset (rdy_reg) for the
purpose of waiting for the power transition to complete. However, a
copy/paste error converting to use the new 64 register functions
switched it to using the pwrtrans_reg register instead. Fix the function
to use the correct register.
Fixes: 4d230aa209 ("drm/panthor: Add 64-bit and poll register accessors")
Signed-off-by: Steven Price <steven.price@arm.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/r/20250630140704.432409-1-steven.price@arm.com
Add missing drm_display_mode DRM_MODE_FLAG_NVSYNC | DRM_MODE_FLAG_NHSYNC
flags. Those are used by various bridges(e.g. dw-mipi-dsi) in the
pipeline to correctly configure its sync signals polarity.
Tested on rk3568/rk3576/rk3588 EVB.
Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250618080955.691048-1-andyshrk@163.com
The DSI host has different modes in prepare() and enable() functions,
prepare() is in LP command mode and enable() is in HS video mode.
>From our experience, generally the initialization sequence needs to be
sent in the LP command mode.
Move the setup init function from enable() to prepare() to fix a display
shift on rk3568 evb.
Tested on rk3568/rk3576/rk3588 EVB.
Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250618091520.691590-1-andyshrk@163.com
Although the datasheet of the panel module describes that it has a
reset pin, in the actual hardware design, we often use an RC circuit
to control the reset, and rarely use GPIO to control the reset. This
is the way it is done on our numerous development boards (such as
RK3568/RK3576 EVB).
So make the reset-gpio optional.
Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250616070536.670519-2-andyshrk@163.com
Although the datasheet of the panel module describes that it has a
reset pin, in the actual hardware design, we often use an RC circuit
to control the reset, and rarely use GPIO to control the reset. This
is the way it is done on our numerous development boards (such as RK3568,
RK3576 EVB).
So make the reset-gpio optional.
Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250616070536.670519-1-andyshrk@163.com
Add support for the 2160x1080 LCD panel from DJN (98-03057-6598B-I)
bundled with a HX83112B driver IC, as found on the Fairphone 3
smartphone.
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Luca Weiss <luca@lucaweiss.eu>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250611-fp3-display-v4-3-ef67701e7687@lucaweiss.eu
Himax HX83112B is a display driver IC used to drive LCD DSI panels.
Describe it and the Fairphone 3 panel (98-03057-6598B-I) from DJN using
it.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Luca Weiss <luca@lucaweiss.eu>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250611-fp3-display-v4-2-ef67701e7687@lucaweiss.eu
Since the drm_mock_scheduler does not have real users in userspace, nor
does it have real hardware or firmware rings, it's not necessary to
signal timedout fences nor free jobs - from a functional standpoint.
Still, the dma_fence framework establishes the hard rule that all fences
must always get signaled.
The unit tests, moreover, should as much as possible represent the
intended usage of the scheduler API.
Furthermore, this later enables simplifying the mock scheduler's
teardown code path.
Make sure timed out hardware fences get signaled with the appropriate
error code.
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250605134154.191764-2-phasta@kernel.org
Use drm dp helper to enable backlight now that it has been modified
to set PANEL_LUMINANCE_CONTROL_ENABLE bit based on if capability
supports it and the driver wants it. Remove the dead code.
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://lore.kernel.org/r/20250620063445.3603086-14-suraj.kandpal@intel.com
Now that drm_edp_backlight init has been modified to take
into account the setup of lumininace based brightness manipulation
we can just use that.
--v2
-Fix commit message [Arun]
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://lore.kernel.org/r/20250620063445.3603086-12-suraj.kandpal@intel.com
Change the argument type to u32 for the default level being sent
since it has to now account for luminance value which has to be
set for DP_EDP_PANEL_LUMINANCE_TARGET_VALUE.
--v2
-No need to typecast [Jani]
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://lore.kernel.org/r/20250620063445.3603086-10-suraj.kandpal@intel.com
Modify drm_edp_backlight_set_level to be able to set the value
for register in DP_EDP_PANEL_TARGET_LUMINANCE_VALUE. We multiply
the level with 1000 since we get the value in Nits and the
register accepts it in milliNits.
--v2
-Add comment regarding the unit [Arun]
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://lore.kernel.org/r/20250620063445.3603086-9-suraj.kandpal@intel.com
Use u32 for level variable as one may need to pass value for
DP_EDP_PANEL_TARGET_LUMINANCE_VALUE.
--v2
-Typecase is not needed [Jani]
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://lore.kernel.org/r/20250620063445.3603086-8-suraj.kandpal@intel.com
Modify drm_edp_probe_state to read current level from
DP_EDP_PANEL_TARGET_LUMINANCE_VALUE. We divide it by
1000 since the value in this register is in millinits.
--v2
-Add comment on the unit sent back [Arun]
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://lore.kernel.org/r/20250620063445.3603086-7-suraj.kandpal@intel.com
Change the current_level argument type to u32 from u16
since it can now carry the value which it gets from
DP_EDP_PANEL_TARGET_LUMINANCE_VALUE.
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://lore.kernel.org/r/20250620063445.3603086-6-suraj.kandpal@intel.com
Use u32 instead of u16 for max variable in drm_edp_backlight_info
since it can now hold max luminance range value which is u32.
We will set this max with max_luminance value when luminance_set is
true.
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://lore.kernel.org/r/20250620063445.3603086-5-suraj.kandpal@intel.com
Add new argument to drm_edp_backlight_init which gives the
max_luminance which will be needed to set the max values for
backlight.
--v2
-Use pass only max luminance instead of luminance_range_info struct
[Arun]
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://lore.kernel.org/r/20250620063445.3603086-4-suraj.kandpal@intel.com
Add bool argument in drm_edp_backlight init to provide the drivers
option to choose if they want to use luminance values to
manipulate brightness.
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://lore.kernel.org/r/20250620063445.3603086-3-suraj.kandpal@intel.com
Introduce luminance_set flag which indicates if we can manipulate
backlight using luminance value or not which is only possible
after eDP v1.5.
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://lore.kernel.org/r/20250620063445.3603086-2-suraj.kandpal@intel.com
As with the RK3588 SoC, RK3576 also allows the use of HDMI PHY PLL as an
alternative and more accurate pixel clock source for VOP2.
Document the optional PLL clock property.
Moreover, given that this is part of a series intended to address some
recent display problems, provide the appropriate tags to facilitate
backporting.
Fixes: c3b7c5a4d7 ("dt-bindings: display: vop2: Add rk3576 support")
Cc: stable@vger.kernel.org
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Reviewed-by: "Rob Herring (Arm)" <robh@kernel.org>
Tested-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20250612-rk3576-hdmitx-fix-v1-1-4b11007d8675@collabora.com
The commit d391c58271 ("drivers/firmware: move x86 Generic System
Framebuffers support") moved the sysfb*.c source files from arch/x86
to drivers/firmware, because the logic wasn't x86 specific and could
be used by other architectures.
But the drivers/firmware path is not listed in MAINTAINERS, which led
to the files being orphaned and scripts/get_maintainer.pl not listing
a mailing list to Cc anymore.
Now that we have an entry for all the firmware-provided framebuffer code,
add the missing sysfb files to make sure correct folks and list is Cc'ed.
Fixes: d391c58271 ("drivers/firmware: move x86 Generic System Framebuffers support")
Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Closes: https://lore.kernel.org/lkml/aF53djlieUNF_-aV@smile.fi.intel.com/
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://lore.kernel.org/r/20250627113328.2703491-1-javierm@redhat.com
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Add FourCC definitions for the 48-bit RGB/BGR formats to the
DRM/KMS uapi.
The format will be used by the Raspberry Pi PiSP Back End,
supported by a V4L2 driver in kernel space and by libcamera in
userspace, which uses the DRM FourCC identifiers.
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Rob Clark <robin.clark@oss.qualcomm.com>
Reviewed-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Link: https://lore.kernel.org/r/20240226132544.82817-1-jacopo.mondi@ideasonboard.com
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Move big-endian support from drm_fb_xrgb8888_to_rgb565() into the new
helper drm_xrgb8888_to_rgb565be(). The functionality is required for
displays with big-endian byte order. Update all callers.
With the change applied, drm_fb_xrgb8888_to_rgb565() has the same
signature as the other conversion functions, which is required for
further updates to drm_fb_blit(). Also makes the format-conversion
helper available to panic handlers, if necessary.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250625114911.1121301-1-tzimmermann@suse.de
Drop the custom MHZ macro and replace it with HZ_PER_MHZ.
Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Link: https://lore.kernel.org/r/20250527-samsung-dsim-v1-2-5be520d84fbb@pengutronix.de
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Turn the open-coded goto-again construct into a while loop, to make
samsung_dsim_transfer_start() a bit shorter and easier to read.
Hold the spinlock when looping back around and avoid the duplicated
list_empty() check.
Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Link: https://lore.kernel.org/r/20250527-samsung-dsim-v1-1-5be520d84fbb@pengutronix.de
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Update header inclusions to follow IWYU (Include What You Use)
principle.
Note that kernel.h is discouraged to be included as it's written
at the top of that file.
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20250627103454.702606-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Add 1, 2, 3, and 4 component 32b float formats, so that buffers with
these formats can be imported/exported with fourcc+modifier, and/or
created by gbm.
These correspond to PIPE_FORMAT_{R32,R32G32,R32G32B32,R32G32B32A32}_FLOAT
in mesa.
v2: Fix comment describing float32 layout [Sima]
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
Acked-by: Simona Vetter <simona@ffwll.ch>
Acked-by: Daniel Stone <daniels@collabora.com>
Link: https://lore.kernel.org/r/20250625173712.116446-3-robin.clark@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Not something that is likely to be scanned out, but GPUs usually support
half-float formats with 1, 2, or possibly 3 components, and it is useful
to be able to import/export them with a valid fourcc, and/or use gbm to
create them.
These correspond to PIPE_FORMAT_{R16,R16G16,R16G16B16}_FLOAT in mesa.
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
Acked-by: Simona Vetter <simona@ffwll.ch>
Acked-by: Daniel Stone <daniels@collabora.com>
Link: https://lore.kernel.org/r/20250625173712.116446-2-robin.clark@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
To avoid duplicating the tricky bo locking implementation,
Implement ttm_lru_walk_for_evict() using the guarded bo LRU iteration.
To facilitate this, support ticketlocking from the guarded bo LRU
iteration.
v2:
- Clean up some static function interfaces (Christian König)
- Fix Handling -EALREADY from ticketlocking in the loop by
skipping to the next item. (Intel CI)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20250623155313.4901-4-thomas.hellstrom@linux.intel.com
Instead of the struct ttm_operation_ctx, Pass a struct ttm_lru_walk_arg
to enable us to easily extend the walk functionality, and to
implement ttm_lru_walk_for_evict() using the guarded LRU iteration.
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20250623155313.4901-3-thomas.hellstrom@linux.intel.com
Let the locking functions take the new struct ttm_lru_walk_arg
as argument in order for them to be easily used from both
types of walk.
v2:
- Whitespace fix
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20250623155313.4901-2-thomas.hellstrom@linux.intel.com
As of commit 92ac7de317 ("gpiolib: don't allow setting values on input
lines"), the GPIO core makes sure values cannot be set on input lines.
Remove the unnecessary check.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20250620074951.32758-1-brgl@bgdev.pl
To the best of my knowledge, all drivers in the mainline kernel adding a
DRM bridge are now converted to using devm_drm_bridge_alloc() for
allocation and initialization. Among others this ensures initialization of
the bridge refcount, allowing dynamic allocation lifetime.
devm_drm_bridge_alloc() is now mandatory for all new bridges. Code using
the old pattern ([devm_]kzalloc + filling the struct fields +
drm_bridge_add) is not allowed anymore.
Any drivers that might have been missed during the conversion, patches in
flight towards mainline and out-of-tre drivers still using the old pattern
will already be caught by a warning looking like:
------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 2 PID: 83 at lib/refcount.c:25 refcount_warn_saturate+0x120/0x148
[...]
Call trace:
refcount_warn_saturate+0x120/0x148 (P)
drm_bridge_get.part.0+0x70/0x98 [drm]
drm_bridge_add+0x34/0x108 [drm]
sn65dsi83_probe+0x200/0x480 [ti_sn65dsi83]
[...]
This warning comes from the refcount code and happens because
drm_bridge_add() is increasing the refcount, which is uninitialized and
thus initially zero.
Having a warning and the corresponding stack trace is surely useful, but
the warning text does not clarify the root problem nor how to fix it.
Add a DRM_WARN() just before increasing the refcount, so the log will be
much more readable:
[drm] DRM bridge corrupted or not allocated by devm_drm_bridge_alloc()
------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
[...etc...]
A DRM_WARN is used because drm_warn and drm_WARN require a struct
drm_device pointer which is not yet available when adding a bridge.
Do not print the dev_name() in the warning because struct drm_bridge has no
pointer to the struct device. The affected driver should be easy to catch
based on the following stack trace however.
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20250620-drm-bridge-alloc-getput-drm-bridge-c-v9-3-ca53372c9a84@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
