According to the eDP specification (VESA Embedded DisplayPort Standard
v1.4b, Section 3.3.10.2), if the value of DP_EDP_PWMGEN_BIT_COUNT is
less than DP_EDP_PWMGEN_BIT_COUNT_CAP_MIN, the sink is required to use
the MIN value as the effective PWM bit count.
This commit updates the logic to clamp the reported
DP_EDP_PWMGEN_BIT_COUNT to the range defined by _CAP_MIN and _CAP_MAX.
As part of this change, the behavior is modified such that reading both
_CAP_MIN and _CAP_MAX registers is now required to succeed, otherwise
bl->max value could end up being not set although
drm_edp_backlight_probe_max() returned success.
This ensures correct handling of eDP panels that report a zero PWM
bit count but still provide valid non-zero MIN and MAX capability
values. Without this clamping, brightness values may be interpreted
incorrectly, leading to a dim or non-functional backlight.
For example, the Samsung ATNA40YK20 OLED panel used in the Lenovo
ThinkPad T14s Gen6 (Snapdragon) reports a PWM bit count of 0, but
supports AUX backlight control and declares a valid 11-bit range.
Clamping ensures brightness scaling works as intended on such panels.
Co-developed-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Christopher Obbard <christopher.obbard@linaro.org>
Tested-by: Christopher Obbard <christopher.obbard@linaro.org>
Reviewed-by: Christopher Obbard <christopher.obbard@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250814-topic-x1e80100-t14s-oled-dp-brightness-v7-1-b3d7b4dfe8c5@linaro.org
Replace vkms' vblank timer with the DRM implementation. The DRM
code is identical in concept, but differs in implementation.
Vblank timers are covered in vblank helpers and initializer macros,
so remove the corresponding hrtimer in struct vkms_output. The
vblank timer calls vkms' custom timeout code via handle_vblank_timeout
in struct drm_crtc_helper_funcs.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Tested-by: Louis Chauvet <louis.chauvet@bootlin.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20250916083816.30275-4-tzimmermann@suse.de
Implement atomic_flush, atomic_enable and atomic_disable of struct
drm_crtc_helper_funcs for vblank handling. Driver with no further
requirements can use these functions instead of adding their own.
Also simplifies the use of vblank timers.
The code has been adopted from vkms, which added the funtionality
in commit 3a0709928b ("drm/vkms: Add vblank events simulated by
hrtimers").
v3:
- mention vkms (Javier)
v2:
- fix docs
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/20250916083816.30275-3-tzimmermann@suse.de
The vblank timer simulates a vblank interrupt for hardware without
support. Rate-limits the display update frequency.
DRM drivers for hardware without vblank support apply display updates
ASAP. A vblank event informs DRM clients of the completed update.
Userspace compositors immediately schedule the next update, which
creates significant load on virtualization outputs. Display updates
are usually fast on virtualization outputs, as their framebuffers are
in regular system memory and there's no hardware vblank interrupt to
throttle the update rate.
The vblank timer is a HR timer that signals the vblank in software.
It limits the update frequency of a DRM driver similar to a hardware
vblank interrupt. The timer is not synchronized to the actual vblank
interval of the display.
The code has been adopted from vkms, which added the funtionality
in commit 3a0709928b ("drm/vkms: Add vblank events simulated by
hrtimers").
The new implementation is part of the existing vblank support,
which sets up the timer automatically. Drivers only have to start
and cancel the vblank timer as part of enabling and disabling the
CRTC. The new vblank helper library provides callbacks for struct
drm_crtc_funcs.
The standard way for handling vblank is to call drm_crtc_handle_vblank().
Drivers that require additional processing, such as vkms, can init
handle_vblank_timeout in struct drm_crtc_helper_funcs to refer to
their timeout handler.
There's a possible deadlock between drm_crtc_handle_vblank() and
hrtimer_cancel(). [1] The implementation avoids to call hrtimer_cancel()
directly and instead signals to the timer function to not restart
itself.
v4:
- fix possible race condition between timeout and atomic commit (Michael)
v3:
- avoid deadlock when cancelling timer (Ville, Lyude)
v2:
- implement vblank timer entirely in vblank helpers
- downgrade overrun warning to debug
- fix docs
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Tested-by: Louis Chauvet <louis.chauvet@bootlin.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/all/20250510094757.4174662-1-zengheng4@huawei.com/ # [1]
Link: https://lore.kernel.org/r/20250916083816.30275-2-tzimmermann@suse.de
The tidss_crtc_reset() function will (rightfully) destroy any
pre-existing state.
However, the tidss CRTC driver has its own CRTC state structure that
subclasses drm_crtc_state, and yet will destroy the previous state
by calling __drm_atomic_helper_crtc_destroy_state() and kfree() on its
drm_crtc_state pointer.
It works only because the drm_crtc_state is the first field in the
structure, and thus its offset is 0. It's incredibly fragile however, so
let's call our destroy implementation in such a case to deal with it
properly.
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://lore.kernel.org/r/20250902-drm-state-readout-v1-22-14ad5315da3f@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20250902-drm-state-readout-v1-22-14ad5315da3f@kernel.org
Call drm_mode_size_dumb() to compute dumb-buffer scanline pitch and
buffer size. Align the pitch to a multiple of 8.
Push the current calculation into the only direct caller imx. Imx's
hardware requires the framebuffer width to be aligned to 8. The
driver's current approach is actually incorrect, as it only guarantees
this implicitly and requires bpp to be a multiple of 8 already. A
later commit will fix this problem by aligning the scanline pitch
such that an aligned width still fits into each scanline's memory.
A number of other drivers are build on top of gem-dma helpers and
implement their own dumb-buffer allocation. These drivers invoke
drm_gem_dma_dumb_create_internal(), which is not affected by this
commit.
v5:
- avoid reset of arguments (Tomi)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://lore.kernel.org/r/20250821081918.79786-4-tzimmermann@suse.de
Add drm_modes_size_dumb(), a helper to calculate the dumb-buffer
scanline pitch and allocation size. Implementations of struct
drm_driver.dumb_create can call the new helper for their size
computations.
There is currently quite a bit of code duplication among DRM's
memory managers. Each calculates scanline pitch and buffer size
from the given arguments, but the implementations are inconsistent
in how they treat alignment and format support. Later patches will
unify this code on top of drm_mode_size_dumb() as much as possible.
drm_mode_size_dumb() uses existing 4CC format helpers to interpret
the given color mode. This makes the dumb-buffer interface behave
similar the kernel's video= parameter. Current per-driver implementations
again likely have subtle differences or bugs in how they support color
modes.
The dumb-buffer UAPI is only specified for known color modes. These
values describe linear, single-plane RGB color formats or legacy index
formats. Other values should not be specified. But some user space
still does. So for unknown color modes, there are a number of known
exceptions for which drm_mode_size_dumb() calculates the pitch from
the bpp value, as before. All other values work the same but print
an error.
v6:
- document additional use cases for DUMB_CREATE2 in TODO list (Tomi)
- fix typos in documentation (Tomi)
v5:
- check for overflows with check_mul_overflow() (Tomi)
v4:
- use %u conversion specifier (Geert)
- list DRM_FORMAT_Dn in UAPI docs (Geert)
- avoid dmesg spamming with drm_warn_once() (Sima)
- add more information about bpp special case (Sima)
- clarify parameters for hardware alignment
- add a TODO item for DUMB_CREATE2
v3:
- document the UAPI semantics
- compute scanline pitch from for unknown color modes (Andy, Tomi)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://lore.kernel.org/r/20250821081918.79786-3-tzimmermann@suse.de
The ioctls MODE_CREATE_DUMB and MODE_MAP_DUMB return results into a
memory buffer supplied by user space. On errors, it is possible that
intermediate values are being returned. The exact semantics depends
on the DRM driver's implementation of these ioctls. Although this is
most-likely not a security problem in practice, avoid any uncertainty
by clearing the memory to 0 on errors.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://lore.kernel.org/r/20250821081918.79786-2-tzimmermann@suse.de
Split off device initialization for Gen7 hardware into the helpers
ast_2600_device_create() and ast_2600_detect_wide_screen(). The new
functions are duplicates of their counterparts in ast_main.c, but
stripped from most non-Gen7 support.
Simplifies maintenance as the driver's number of supported hardware
generations grows.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250922083708.45564-12-tzimmermann@suse.de
Split off device initialization for Gen6 hardware into the helpers
ast_2500_device_create() and ast_2500_detect_wide_screen(). The new
functions are duplicates of their counterparts in ast_main.c, but
stripped from most non-Gen6 support.
Simplifies maintenance as the driver's number of supported hardware
generations grows.
v2:
- simplify widescreen-detection logic
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250922083708.45564-11-tzimmermann@suse.de
Split off device initialization for Gen5 hardware into the helpers
ast_2400_device_create() and ast_2400_detect_wide_screen(). The new
functions are duplicates of their counterparts in ast_main.c, but
stripped from most non-Gen5 support.
Simplifies maintenance as the driver's number of supported hardware
generations grows.
v2:
- simplify widescreen-detection logic
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250922083708.45564-10-tzimmermann@suse.de
Split off device initialization for Gen4 hardware into the helpers
ast_2300_device_create() and ast_2300_detect_wide_screen(). The new
functions are duplicates of their counterparts in ast_main.c, but
stripped from most non-Gen4 support.
Simplifies maintenance as the driver's number of supported hardware
generations grows.
v2:
- simplify widescreen-detection logic
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250922083708.45564-9-tzimmermann@suse.de
Split off device initialization for Gen3 hardware into the helpers
ast_2200_device_create() and ast_2200_detect_wide_screen(). The new
functions are duplicates of their counterparts in ast_main.c, but
stripped from most non-Gen3 support.
Simplifies maintenance as the driver's number of supported hardware
generations grows.
v2:
- simplify widescreen-detection logic
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250922083708.45564-8-tzimmermann@suse.de
Split off device initialization for Gen2 hardware into the helpers
ast_2100_device_create() and ast_2100_detect_wide_screen(). The new
functions are duplicates of their counterparts in ast_main.c, but
stripped from most non-Gen2 support.
Simplifies maintenance as the driver's number of supported hardware
generations grows.
v2:
- simplify widescreen-detection logic (Jocelyn)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250922083708.45564-7-tzimmermann@suse.de
Split off device initialization for Gen1 hardware into the helper
ast_2000_device_create(). The new function is a duplicate of their
counterpart in ast_main.c, but stripped from most non-Gen1 support.
Simplifies maintenance as the driver's number of supported hardware
generations grows.
v2:
- remove unnecessary widescreen-detection logic
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250922083708.45564-6-tzimmermann@suse.de
Gen4 and later models detect the TX chip from VGACRD1, while earlier
models detect from VGACRA3. Split up the detection helper into
two separate helpers. Use SZ_ constants instead of plain numbers.
Then inline the call into its only caller ast_device_create(). When
ast_device_create() gets split up per Gen, either call will remain.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250922083708.45564-4-tzimmermann@suse.de
The HDMI TX Parallel Audio Interface (HTX_PAI) is a digital module that
acts as the bridge between the Audio Subsystem to the HDMI TX Controller.
This IP block is found in the HDMI subsystem of the i.MX8MP SoC.
Data received from the audio subsystem can have an arbitrary component
ordering. The HTX_PAI block has integrated muxing options to select which
sections of the 32-bit input data word will be mapped to each IEC60958
field. The HTX_PAI_FIELD_CTRL register contains mux selects to
individually select P,C,U,V,Data, and Preamble.
Use component helper so that imx8mp-hdmi-tx will be aggregate driver,
imx8mp-hdmi-pai will be component driver, then imx8mp-hdmi-pai can use
bind() ops to get the plat_data from imx8mp-hdmi-tx device.
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Reviewed-by: Liu Ying <victor.liu@nxp.com>
Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Liu Ying <victor.liu@nxp.com>
Link: https://lore.kernel.org/r/20250923053001.2678596-6-shengjiu.wang@nxp.com
