Re: [PATCH v0 00/10] i.MX8MP HDMI support

[Alexander Stein <alexander.stein@ew.tq-group.com>]

Hello Lucas,

Am Mittwoch, 6. April 2022, 18:01:13 CEST schrieb Lucas Stach:
> Hi all,
> 
> this adds support for the HDMI output pipeline on the i.MX8MP.
> It currently depends on the i.MX8MP HDMI power domain series [1]
> and support for the new LCDIF [2] in the i.MX8MP. I guess the
> implementation presented here also still has some warts that
> require fixing and the individual patches most likely need to go
> through different maintainer trees, so I don't expect this series
> to be applied right away.
> 
> However this complete series should allow people to test it more
> easily and provide feedback on the implementation with the full
> picture available.
> 
> Compared to downstream this implementation actually allows to
> power down the separate HDMI PHY power domain when the display
> is inactive or no HDMI cable is connected.

Thanks for these patches.
I tried using them on my imx8mp based board (TQMa8MPxL + MBa8MPxL) but failed 
to get the display showing anything. I noticed several things though:

* For some reason the HDMI PHY PLL does not lock. I get the error
> fsl-samsung-hdmi-phy 32fdff00.phy: PLL failed to lock
Increasing timeout does not change anything.

* The HDMI bridge wants to use bus format 0x200f which is not supported by 
lcdif.
> lcdif 32fc6000.display-controller: Unknown media bus format 0x200f
I wonder which part in the DRM chain choses to use this.
But even hard limiting to 0x100a the screen stayed in suspend

* If the drivers are built as modules I get a hard lockup during boot. Using 
built-in drivers or 'clk_ignore_unused' workarounds this.

* DDC does actually work. The display is detected and EDID can be read.

* Sometimes I get the following error:
------------[ cut here ]------------
[CRTC:33:crtc-0] vblank wait timed out
WARNING: CPU: 2 PID: 151 at drivers/gpu/drm/drm_atomic_helper.c:1529 
drm_atomic_helper_wait_for_vblanks.part.0+0x2ac/0x2fc
Modules linked in: caamhash_desc caamalg_desc crypto_engine rng_core mcp320x 
dw_hdmi_cec authenc libdes dw100 videobuf2_dma_contig lcdif crct10dif_ce 
phy_fsl_samsung_hdmi v4l2_mem2mem imx_sdma flexcan imx8mm_thermal can_dev caam 
error pwm_fan fuse ipv6
CPU: 2 PID: 151 Comm: kworker/u8:7 Not tainted 5.18.0-rc2-next-20220412+ #165 
d226098cac46ded24901c7090f909ca8f5098eb0
Hardware name: TQ-Systems i.MX8MPlus TQMa8MPxL on MBa8MPxL (DT)
Workqueue: events_unbound deferred_probe_work_func
pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : drm_atomic_helper_wait_for_vblanks.part.0+0x2ac/0x2fc
lr : drm_atomic_helper_wait_for_vblanks.part.0+0x2ac/0x2fc
sp : ffff80000a133430
x29: ffff80000a133430 x28: 0000000000000000 x27: 0000000000000000
x26: 0000000000000000 x25: 0000000000000001 x24: ffff80000935f030
x23: ffff00000433e000 x22: ffff0000029e7000 x21: 0000000000000001
x20: ffff000002e7fb48 x19: 0000000000000000 x18: 0000000000000001
x17: 4d554e5145530065 x16: 6c75646f6d3d4d45 x15: 5453595342555300
x14: 0000000000000000 x13: 0a74756f2064656d x12: 6974207469617720
x11: 0000000000000000 x10: 000000000000003a x9 : ffff80000a133430
x8 : 00000000ffffffff x7 : 6974207469617720 x6 : 6b6e616c6276205d
x5 : ffff00007fb91b00 x4 : 0000000000000000 x3 : 0000000000000027
x2 : 0000000000000023 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
 drm_atomic_helper_wait_for_vblanks.part.0+0x2ac/0x2fc
 drm_atomic_helper_commit_tail_rpm+0x80/0xa0
 commit_tail+0xcc/0x1f0
 drm_atomic_helper_commit+0x13c/0x370
 drm_atomic_commit+0xa4/0xe0
 drm_client_modeset_commit_atomic+0x1fc/0x250
 drm_client_modeset_commit_locked+0x58/0xa0
 drm_client_modeset_commit+0x2c/0x50
 __drm_fb_helper_restore_fbdev_mode_unlocked+0xec/0x140
 drm_fb_helper_set_par+0x38/0x6c
 fbcon_init+0x264/0x5e4
 visual_init+0xc8/0x15c
 do_bind_con_driver.isra.0+0x20c/0x470
 do_take_over_console+0x44/0x60
 do_fbcon_takeover+0x80/0x140
 fbcon_fb_registered+0x1c4/0x260
 do_register_framebuffer+0x1e0/0x2d0
 register_framebuffer+0x2c/0x50
 __drm_fb_helper_initial_config_and_unlock+0x9c/0x130
 drm_fbdev_client_hotplug+0x1a8/0x20c
 drm_fbdev_generic_setup+0xc0/0x1d0
 lcdif_probe+0x7c/0xa0 [lcdif e756925430e957a7bc9e6376ad5964e4b1cb143e]
 platform_probe+0x64/0x100
 call_driver_probe+0x28/0x130
 really_probe+0x178/0x310
 __driver_probe_device+0xfc/0x144
 driver_probe_device+0x38/0x12c
 __device_attach_driver+0xd4/0x180
 bus_for_each_drv+0x74/0xc4
 __device_attach+0xd8/0x1e0
 device_initial_probe+0x10/0x20
 bus_probe_device+0x90/0xa0
 deferred_probe_work_func+0x9c/0xf0
 process_one_work+0x1d0/0x330
 worker_thread+0x68/0x390
 kthread+0xec/0xfc
 ret_from_fork+0x10/0x20
---[ end trace 0000000000000000 ]---

But given that the PLL did not lock I assume this is not too surprising.

Best regards,
Alexander