[PATCH v3 11/13] drm/fb-helper: Fix single-probe color-format selection

Wed Jan 4 10:34:24 UTC 2023

On 1/4/23 05:14, Thomas Zimmermann wrote:
> Hi
> 
> Thanks for reporting the problem.
> 
> Am 03.01.23 um 22:18 schrieb Maíra Canal:
>> Hi Thomas,
>>
>> On 1/2/23 08:29, Thomas Zimmermann wrote:
>>> Fix the color-format selection of the single-probe helper. Go
>>> through all user-specified values and test each for compatibility
>>> with the driver. If none is supported, use the driver-provided
>>> default. This guarantees that the console is always available in
>>> any color format at least.
>>>
>>> Until now, the format selection of the single-probe helper tried
>>> to either use a user-specified format or a 32-bit default format.
>>> If the user-specified format was not supported by the driver, the
>>> selection failed and the display remained blank.
>>>
>>> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
>>> Reviewed-by: Javier Martinez Canillas <javierm at redhat.com>
>>> ---
>>
>> I started to get the following warning on the Raspberry Pi 4 Model B
>> (arm64/defconfig) using drm-misc-next:
>>
>> [    4.376317] [drm] Initialized vc4 0.0.0 20140616 for gpu on minor 0
>> [    4.433587] vc4-drm gpu: [drm] bpp/depth value of 16/24 not supported
>> [    4.433617] vc4-drm gpu: [drm] bpp/depth value of 16/24 not supported
>> [    4.433629] vc4-drm gpu: [drm] bpp/depth value of 16/24 not supported
>> [    4.433640] vc4-drm gpu: [drm] bpp/depth value of 16/24 not supported
>> [    4.433650] vc4-drm gpu: [drm] bpp/depth value of 16/24 not supported
>> [    4.433658] vc4-drm gpu: [drm] No compatible format found
>> [    4.433854] ------------[ cut here ]------------
>> [    4.433861] WARNING: CPU: 2 PID: 66 at drivers/gpu/drm/drm_atomic.c:1604 __drm_atomic_helper_set_config+0x2e8/0x314 [drm]
>> [    4.434172] Modules linked in: btbcm(+) crct10dif_ce reset_raspberrypi clk_raspberrypi raspberrypi_hwmon bluetooth ecdh_generic ecc
>> pwm_bcm2835 broadcom rfkill iproc_rng200 bcm_phy_lib i2c_bcm2835 vc4 rng_core snd_soc_hdmi_codec bcm2711_thermal cec drm_display_helper
>> v3d pcie_brcmstb drm_dma_helper gpu_sched genet drm_shmem_helper nvmem_rmem mdio_bcm_unimac drm_kms_helper drm fuse ip_tables x_tables
>> ipv6
>> [    4.434322] CPU: 2 PID: 66 Comm: kworker/u8:2 Not tainted 6.1.0-rc6-00011-g37c90d589dc0 #29
>> [    4.434337] Hardware name: Raspberry Pi 4 Model B Rev 1.4 (DT)
>> [    4.434345] Workqueue: events_unbound deferred_probe_work_func
>> [    4.434376] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>> [    4.434390] pc : __drm_atomic_helper_set_config+0x2e8/0x314 [drm]
>> [    4.434668] lr : __drm_atomic_helper_set_config+0x64/0x314 [drm]
>> [    4.434943] sp : ffff8000082c3840
>> [    4.434949] x29: ffff8000082c3850 x28: ffff2d6d448e12c0 x27: 0000000000000001
>> [    4.434972] x26: 0000000000000038 x25: ffff2d6d448e12c0 x24: ffff2d6d401a0690
>> [    4.434991] x23: ffff2d6d41f74080 x22: ffff2d6d40d8a400 x21: ffff2d6d433fcc00
>> [    4.435009] x20: ffff2d6d401a0690 x19: ffff2d6d44b8e180 x18: 0000000000000020
>> [    4.435027] x17: 0000000000000010 x16: ffffa6757bee52d0 x15: 0000000000000000
>> [    4.435044] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
>> [    4.435063] x11: 0000000000000000 x10: ffff2d6d43240800 x9 : ffff2d6d44b8e200
>> [    4.435081] x8 : 0000000000000000 x7 : ffff2d6d44b8e180 x6 : ffff2d6d40d8a400
>> [    4.435099] x5 : ffff2d6d45e7ca80 x4 : 0000000000000050 x3 : ffffa675498c3bad
>> [    4.435116] x2 : 0000000000000004 x1 : ffff2d6d4323f080 x0 : ffff2d6d433fcc00
>> [    4.435136] Call trace:
>> [    4.435143]  __drm_atomic_helper_set_config+0x2e8/0x314 [drm]
>> [    4.435440]  drm_client_modeset_commit_atomic+0x140/0x244 [drm]
>> [    4.435723]  drm_client_modeset_commit_locked+0x50/0x168 [drm]
>> [    4.436001]  drm_client_modeset_commit+0x2c/0x54 [drm]
>> [    4.436273]  __drm_fb_helper_initial_config_and_unlock+0x548/0x5a0 [drm_kms_helper]
>> [    4.436407]  drm_fb_helper_initial_config+0x38/0x50 [drm_kms_helper]
>> [    4.436528]  drm_fbdev_client_hotplug+0xa8/0x120 [drm_kms_helper]
>> [    4.436648]  drm_fbdev_generic_setup+0x80/0x150 [drm_kms_helper]
>> [    4.436768]  vc4_drm_bind+0x1f0/0x22c [vc4]
>> [    4.436928]  try_to_bring_up_aggregate_device+0x168/0x1b4
>> [    4.436958]  __component_add+0xbc/0x15c
>> [    4.436974]  component_add+0x14/0x20
>> [    4.436990]  vc4_hdmi_dev_probe+0x1c/0x28 [vc4]
>> [    4.437146]  platform_probe+0xa8/0xd0
>> [    4.437158]  really_probe+0x130/0x2f4
>> [    4.437174]  __driver_probe_device+0xb4/0xe0
>> [    4.437189]  driver_probe_device+0x3c/0x1f8
>> [    4.437202]  __device_attach_driver+0x118/0x140
>> [    4.437217]  bus_for_each_drv+0x84/0xd0
>> [    4.437229]  __device_attach+0xd0/0x19c
>> [    4.437243]  device_initial_probe+0x14/0x20
>> [    4.437256]  bus_probe_device+0x34/0x98
>> [    4.437268]  deferred_probe_work_func+0x88/0xc4
>> [    4.437282]  process_one_work+0x1cc/0x2c8
>> [    4.437295]  worker_thread+0x248/0x458
>> [    4.437304]  kthread+0xec/0x198
>> [    4.437319]  ret_from_fork+0x10/0x20
>> [    4.437333] ---[ end trace 0000000000000000 ]---
>>
>> After bisecting the problem, I was able to detect that the warning started to
>> appear on the commit 37c90d589dc0 ("drm/fb-helper: Fix single-probe color-format
>> selection").
>>
>> Do you have any idea on what might be causing this warning?
> 
> vc4 wants 16 bits per pixel and 24-bit color depth at the same time. That makes no sense.
> 
> Does it work if you call drm_fbdev_generic_setup() with 32 bpp at [1]? Like this:
> 
>    drm_fbdev_generic_setup(drm, 32)

I wasn't able to reproduce the problem again with 32 bpp. Maybe you could send a patch
fixing it, so that Maxime could that a look and check if there is any problem with using
32 bpp.

Thanks for figuring out the problem!

Best Regards,
- Maíra Canal

> 
> Best regards
> Thomas
> 
> [1] https://elixir.bootlin.com/linux/v6.2-rc2/source/drivers/gpu/drm/vc4/vc4_drv.c#L391
> 
>>
>> Best Regards,
>> - Maíra Canal
> 