[BUG] drm/vc4: vblank wait timed out

[BUG] drm/vc4: vblank wait timed out

[Stefan Wahren]

Hi,

after submit of the latest bcm2835 clock fixes, i thought this issue has been fixed. But i've seen this issue with current mainline 4.17-rc3 (bcm2835_defconfig) on Raspberry Pi 1 B (using U-Boot TFTP Boot). Strangly i couldn't reproduce this issue with same kernel but using only the Foundation bootloader (without U-Boot TFTP Boot).

U-Boot version: 2018.03

I triggered the warning using my HDMI switch:

[  198.304572] ------------[ cut here ]------------
[  198.304693] WARNING: CPU: 0 PID: 10 at drivers/gpu/drm/drm_atomic_helper.c:1351 drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0
[  198.304703] [CRTC:68:crtc-2] vblank wait timed out
[  198.304751] Modules linked in: bcm2835_rng rng_core vchiq(C)
[  198.304790] CPU: 0 PID: 10 Comm: kworker/0:1 Tainted: G         C        4.17.0-rc3+ #1
[  198.304796] Hardware name: BCM2835
[  198.304817] Workqueue: events output_poll_execute
[  198.304867] [<c010f8d8>] (unwind_backtrace) from [<c010cda4>] (show_stack+0x20/0x24)
[  198.304934] [<c010cda4>] (show_stack) from [<c079ae74>] (dump_stack+0x20/0x28)
[  198.304971] [<c079ae74>] (dump_stack) from [<c011e61c>] (__warn+0xec/0x104)
[  198.305012] [<c011e61c>] (__warn) from [<c011e67c>] (warn_slowpath_fmt+0x48/0x50)
[  198.305048] [<c011e67c>] (warn_slowpath_fmt) from [<c0421638>] (drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0)
[  198.305098] [<c0421638>] (drm_atomic_helper_wait_for_vblanks) from [<c0455ce8>] (vc4_atomic_complete_commit+0x80/0xb8)
[  198.305144] [<c0455ce8>] (vc4_atomic_complete_commit) from [<c0455e30>] (vc4_atomic_commit+0x110/0x11c)
[  198.305174] [<c0455e30>] (vc4_atomic_commit) from [<c043dbac>] (drm_atomic_commit+0x50/0x60)
[  198.305202] [<c043dbac>] (drm_atomic_commit) from [<c04251e4>] (restore_fbdev_mode_atomic+0x80/0x1cc)
[  198.305228] [<c04251e4>] (restore_fbdev_mode_atomic) from [<c0426a8c>] (restore_fbdev_mode+0x38/0x144)
[  198.305270] [<c0426a8c>] (restore_fbdev_mode) from [<c0427fa8>] (drm_fb_helper_restore_fbdev_mode_unlocked+0x58/0x8c)
[  198.305296] [<c0427fa8>] (drm_fb_helper_restore_fbdev_mode_unlocked) from [<c0428030>] (drm_fb_helper_set_par+0x54/0x60)
[  198.305320] [<c0428030>] (drm_fb_helper_set_par) from [<c0427f44>] (drm_fb_helper_hotplug_event+0xc8/0xd4)
[  198.305343] [<c0427f44>] (drm_fb_helper_hotplug_event) from [<c0428078>] (drm_fb_helper_output_poll_changed+0x1c/0x20)
[  198.305382] [<c0428078>] (drm_fb_helper_output_poll_changed) from [<c0419494>] (drm_kms_helper_hotplug_event+0x34/0x38)
[  198.305409] [<c0419494>] (drm_kms_helper_hotplug_event) from [<c041963c>] (output_poll_execute+0x16c/0x17c)
[  198.305440] [<c041963c>] (output_poll_execute) from [<c01337e4>] (process_one_work+0x1e0/0x368)
[  198.305466] [<c01337e4>] (process_one_work) from [<c0134620>] (worker_thread+0x2a0/0x418)
[  198.305511] [<c0134620>] (worker_thread) from [<c0138fa8>] (kthread+0x144/0x15c)
[  198.305539] [<c0138fa8>] (kthread) from [<c01010e8>] (ret_from_fork+0x14/0x2c)
[  198.305549] Exception stack(0xc9939fb0 to 0xc9939ff8)
[  198.305562] 9fa0:                                     00000000 00000000 00000000 00000000
[  198.305578] 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[  198.305591] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[  198.305630] ---[ end trace 9c4071c657268b83 ]---

I also dumped clk_summary in both cases, but they were identical.

Are their any helpful information, which i can provide?

Best regards
Stefan
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Re: [BUG] drm/vc4: vblank wait timed out

[Boris Brezillon]

On Sat, 5 May 2018 13:47:25 +0200 (CEST)
Stefan Wahren <stefan.wahren@i2se.com> wrote:

> Hi,
> 
> after submit of the latest bcm2835 clock fixes, i thought this issue has been fixed. But i've seen this issue with current mainline 4.17-rc3 (bcm2835_defconfig) on Raspberry Pi 1 B (using U-Boot TFTP Boot). Strangly i couldn't reproduce this issue with same kernel but using only the Foundation bootloader (without U-Boot TFTP Boot).
> 
> U-Boot version: 2018.03
> 
> I triggered the warning using my HDMI switch:
> 
> [  198.304572] ------------[ cut here ]------------
> [  198.304693] WARNING: CPU: 0 PID: 10 at drivers/gpu/drm/drm_atomic_helper.c:1351 drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0
> [  198.304703] [CRTC:68:crtc-2] vblank wait timed out
> [  198.304751] Modules linked in: bcm2835_rng rng_core vchiq(C)
> [  198.304790] CPU: 0 PID: 10 Comm: kworker/0:1 Tainted: G         C        4.17.0-rc3+ #1
> [  198.304796] Hardware name: BCM2835
> [  198.304817] Workqueue: events output_poll_execute
> [  198.304867] [<c010f8d8>] (unwind_backtrace) from [<c010cda4>] (show_stack+0x20/0x24)
> [  198.304934] [<c010cda4>] (show_stack) from [<c079ae74>] (dump_stack+0x20/0x28)
> [  198.304971] [<c079ae74>] (dump_stack) from [<c011e61c>] (__warn+0xec/0x104)
> [  198.305012] [<c011e61c>] (__warn) from [<c011e67c>] (warn_slowpath_fmt+0x48/0x50)
> [  198.305048] [<c011e67c>] (warn_slowpath_fmt) from [<c0421638>] (drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0)
> [  198.305098] [<c0421638>] (drm_atomic_helper_wait_for_vblanks) from [<c0455ce8>] (vc4_atomic_complete_commit+0x80/0xb8)
> [  198.305144] [<c0455ce8>] (vc4_atomic_complete_commit) from [<c0455e30>] (vc4_atomic_commit+0x110/0x11c)
> [  198.305174] [<c0455e30>] (vc4_atomic_commit) from [<c043dbac>] (drm_atomic_commit+0x50/0x60)
> [  198.305202] [<c043dbac>] (drm_atomic_commit) from [<c04251e4>] (restore_fbdev_mode_atomic+0x80/0x1cc)
> [  198.305228] [<c04251e4>] (restore_fbdev_mode_atomic) from [<c0426a8c>] (restore_fbdev_mode+0x38/0x144)
> [  198.305270] [<c0426a8c>] (restore_fbdev_mode) from [<c0427fa8>] (drm_fb_helper_restore_fbdev_mode_unlocked+0x58/0x8c)
> [  198.305296] [<c0427fa8>] (drm_fb_helper_restore_fbdev_mode_unlocked) from [<c0428030>] (drm_fb_helper_set_par+0x54/0x60)
> [  198.305320] [<c0428030>] (drm_fb_helper_set_par) from [<c0427f44>] (drm_fb_helper_hotplug_event+0xc8/0xd4)
> [  198.305343] [<c0427f44>] (drm_fb_helper_hotplug_event) from [<c0428078>] (drm_fb_helper_output_poll_changed+0x1c/0x20)
> [  198.305382] [<c0428078>] (drm_fb_helper_output_poll_changed) from [<c0419494>] (drm_kms_helper_hotplug_event+0x34/0x38)
> [  198.305409] [<c0419494>] (drm_kms_helper_hotplug_event) from [<c041963c>] (output_poll_execute+0x16c/0x17c)
> [  198.305440] [<c041963c>] (output_poll_execute) from [<c01337e4>] (process_one_work+0x1e0/0x368)
> [  198.305466] [<c01337e4>] (process_one_work) from [<c0134620>] (worker_thread+0x2a0/0x418)
> [  198.305511] [<c0134620>] (worker_thread) from [<c0138fa8>] (kthread+0x144/0x15c)
> [  198.305539] [<c0138fa8>] (kthread) from [<c01010e8>] (ret_from_fork+0x14/0x2c)
> [  198.305549] Exception stack(0xc9939fb0 to 0xc9939ff8)
> [  198.305562] 9fa0:                                     00000000 00000000 00000000 00000000
> [  198.305578] 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> [  198.305591] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> [  198.305630] ---[ end trace 9c4071c657268b83 ]---
> 
> I also dumped clk_summary in both cases, but they were identical.
> 
> Are their any helpful information, which i can provide?

I doubt this will fix your problem, but can you try with this patch
[1] applied?

Also, is u-boot touching PLLH or anything related to HDMI?

[1]https://patchwork.kernel.org/patch/10207159/
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Re: [BUG] drm/vc4: vblank wait timed out

[Stefan Schake]

On Sat, May 5, 2018 at 1:47 PM, Stefan Wahren <stefan.wahren@i2se.com> wrote:
> Hi,
>
> after submit of the latest bcm2835 clock fixes, i thought this issue has been fixed. But i've seen this issue with current mainline 4.17-rc3 (bcm2835_defconfig) on Raspberry Pi 1 B (using U-Boot TFTP Boot). Strangly i couldn't reproduce this issue with same kernel but using only the Foundation bootloader (without U-Boot TFTP Boot).
>
> U-Boot version: 2018.03
>
> I triggered the warning using my HDMI switch:
>
> [  198.304572] ------------[ cut here ]------------
> [  198.304693] WARNING: CPU: 0 PID: 10 at drivers/gpu/drm/drm_atomic_helper.c:1351 drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0
> [  198.304703] [CRTC:68:crtc-2] vblank wait timed out
> [  198.304751] Modules linked in: bcm2835_rng rng_core vchiq(C)
> [  198.304790] CPU: 0 PID: 10 Comm: kworker/0:1 Tainted: G         C        4.17.0-rc3+ #1
> [  198.304796] Hardware name: BCM2835
> [  198.304817] Workqueue: events output_poll_execute
> [  198.304867] [<c010f8d8>] (unwind_backtrace) from [<c010cda4>] (show_stack+0x20/0x24)
> [  198.304934] [<c010cda4>] (show_stack) from [<c079ae74>] (dump_stack+0x20/0x28)
> [  198.304971] [<c079ae74>] (dump_stack) from [<c011e61c>] (__warn+0xec/0x104)
> [  198.305012] [<c011e61c>] (__warn) from [<c011e67c>] (warn_slowpath_fmt+0x48/0x50)
> [  198.305048] [<c011e67c>] (warn_slowpath_fmt) from [<c0421638>] (drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0)
> [  198.305098] [<c0421638>] (drm_atomic_helper_wait_for_vblanks) from [<c0455ce8>] (vc4_atomic_complete_commit+0x80/0xb8)
> [  198.305144] [<c0455ce8>] (vc4_atomic_complete_commit) from [<c0455e30>] (vc4_atomic_commit+0x110/0x11c)
> [  198.305174] [<c0455e30>] (vc4_atomic_commit) from [<c043dbac>] (drm_atomic_commit+0x50/0x60)
> [  198.305202] [<c043dbac>] (drm_atomic_commit) from [<c04251e4>] (restore_fbdev_mode_atomic+0x80/0x1cc)
> [  198.305228] [<c04251e4>] (restore_fbdev_mode_atomic) from [<c0426a8c>] (restore_fbdev_mode+0x38/0x144)
> [  198.305270] [<c0426a8c>] (restore_fbdev_mode) from [<c0427fa8>] (drm_fb_helper_restore_fbdev_mode_unlocked+0x58/0x8c)
> [  198.305296] [<c0427fa8>] (drm_fb_helper_restore_fbdev_mode_unlocked) from [<c0428030>] (drm_fb_helper_set_par+0x54/0x60)
> [  198.305320] [<c0428030>] (drm_fb_helper_set_par) from [<c0427f44>] (drm_fb_helper_hotplug_event+0xc8/0xd4)
> [  198.305343] [<c0427f44>] (drm_fb_helper_hotplug_event) from [<c0428078>] (drm_fb_helper_output_poll_changed+0x1c/0x20)
> [  198.305382] [<c0428078>] (drm_fb_helper_output_poll_changed) from [<c0419494>] (drm_kms_helper_hotplug_event+0x34/0x38)
> [  198.305409] [<c0419494>] (drm_kms_helper_hotplug_event) from [<c041963c>] (output_poll_execute+0x16c/0x17c)
> [  198.305440] [<c041963c>] (output_poll_execute) from [<c01337e4>] (process_one_work+0x1e0/0x368)
> [  198.305466] [<c01337e4>] (process_one_work) from [<c0134620>] (worker_thread+0x2a0/0x418)
> [  198.305511] [<c0134620>] (worker_thread) from [<c0138fa8>] (kthread+0x144/0x15c)
> [  198.305539] [<c0138fa8>] (kthread) from [<c01010e8>] (ret_from_fork+0x14/0x2c)
> [  198.305549] Exception stack(0xc9939fb0 to 0xc9939ff8)
> [  198.305562] 9fa0:                                     00000000 00000000 00000000 00000000
> [  198.305578] 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> [  198.305591] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> [  198.305630] ---[ end trace 9c4071c657268b83 ]---
>
> I also dumped clk_summary in both cases, but they were identical.
>
> Are their any helpful information, which i can provide?
>
> Best regards
> Stefan

I have seen this happen with one of those cheap Waveshare HDMI displays.
More often when connecting its power to the RPi versus on a separate
supply. Goes away when using a real, proper HDMI display. They come with
bad EDID data so I pretty much just blamed the display at the time.

Does this happen during a switch and whats on the other end?

Thanks,
Stefan
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Re: [BUG] drm/vc4: vblank wait timed out

[Stefan Wahren]

Hi Boris,

> Boris Brezillon <boris.brezillon@bootlin.com> hat am 5. Mai 2018 um 14:24 geschrieben:
> 
> 
> On Sat, 5 May 2018 13:47:25 +0200 (CEST)
> Stefan Wahren <stefan.wahren@i2se.com> wrote:
> 
> > Hi,
> > 
> > after submit of the latest bcm2835 clock fixes, i thought this issue has been fixed. But i've seen this issue with current mainline 4.17-rc3 (bcm2835_defconfig) on Raspberry Pi 1 B (using U-Boot TFTP Boot). Strangly i couldn't reproduce this issue with same kernel but using only the Foundation bootloader (without U-Boot TFTP Boot).
> > 
> > U-Boot version: 2018.03
> > 
> > I triggered the warning using my HDMI switch:
> > 
> > [  198.304572] ------------[ cut here ]------------
> > [  198.304693] WARNING: CPU: 0 PID: 10 at drivers/gpu/drm/drm_atomic_helper.c:1351 drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0
> > [  198.304703] [CRTC:68:crtc-2] vblank wait timed out
> > [  198.304751] Modules linked in: bcm2835_rng rng_core vchiq(C)
> > [  198.304790] CPU: 0 PID: 10 Comm: kworker/0:1 Tainted: G         C        4.17.0-rc3+ #1
> > [  198.304796] Hardware name: BCM2835
> > [  198.304817] Workqueue: events output_poll_execute
> > [  198.304867] [<c010f8d8>] (unwind_backtrace) from [<c010cda4>] (show_stack+0x20/0x24)
> > [  198.304934] [<c010cda4>] (show_stack) from [<c079ae74>] (dump_stack+0x20/0x28)
> > [  198.304971] [<c079ae74>] (dump_stack) from [<c011e61c>] (__warn+0xec/0x104)
> > [  198.305012] [<c011e61c>] (__warn) from [<c011e67c>] (warn_slowpath_fmt+0x48/0x50)
> > [  198.305048] [<c011e67c>] (warn_slowpath_fmt) from [<c0421638>] (drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0)
> > [  198.305098] [<c0421638>] (drm_atomic_helper_wait_for_vblanks) from [<c0455ce8>] (vc4_atomic_complete_commit+0x80/0xb8)
> > [  198.305144] [<c0455ce8>] (vc4_atomic_complete_commit) from [<c0455e30>] (vc4_atomic_commit+0x110/0x11c)
> > [  198.305174] [<c0455e30>] (vc4_atomic_commit) from [<c043dbac>] (drm_atomic_commit+0x50/0x60)
> > [  198.305202] [<c043dbac>] (drm_atomic_commit) from [<c04251e4>] (restore_fbdev_mode_atomic+0x80/0x1cc)
> > [  198.305228] [<c04251e4>] (restore_fbdev_mode_atomic) from [<c0426a8c>] (restore_fbdev_mode+0x38/0x144)
> > [  198.305270] [<c0426a8c>] (restore_fbdev_mode) from [<c0427fa8>] (drm_fb_helper_restore_fbdev_mode_unlocked+0x58/0x8c)
> > [  198.305296] [<c0427fa8>] (drm_fb_helper_restore_fbdev_mode_unlocked) from [<c0428030>] (drm_fb_helper_set_par+0x54/0x60)
> > [  198.305320] [<c0428030>] (drm_fb_helper_set_par) from [<c0427f44>] (drm_fb_helper_hotplug_event+0xc8/0xd4)
> > [  198.305343] [<c0427f44>] (drm_fb_helper_hotplug_event) from [<c0428078>] (drm_fb_helper_output_poll_changed+0x1c/0x20)
> > [  198.305382] [<c0428078>] (drm_fb_helper_output_poll_changed) from [<c0419494>] (drm_kms_helper_hotplug_event+0x34/0x38)
> > [  198.305409] [<c0419494>] (drm_kms_helper_hotplug_event) from [<c041963c>] (output_poll_execute+0x16c/0x17c)
> > [  198.305440] [<c041963c>] (output_poll_execute) from [<c01337e4>] (process_one_work+0x1e0/0x368)
> > [  198.305466] [<c01337e4>] (process_one_work) from [<c0134620>] (worker_thread+0x2a0/0x418)
> > [  198.305511] [<c0134620>] (worker_thread) from [<c0138fa8>] (kthread+0x144/0x15c)
> > [  198.305539] [<c0138fa8>] (kthread) from [<c01010e8>] (ret_from_fork+0x14/0x2c)
> > [  198.305549] Exception stack(0xc9939fb0 to 0xc9939ff8)
> > [  198.305562] 9fa0:                                     00000000 00000000 00000000 00000000
> > [  198.305578] 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> > [  198.305591] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> > [  198.305630] ---[ end trace 9c4071c657268b83 ]---
> > 
> > I also dumped clk_summary in both cases, but they were identical.
> > 
> > Are their any helpful information, which i can provide?
> 
> I doubt this will fix your problem, but can you try with this patch
> [1] applied?

Unfortunately the issue still persists with patch applied.

> 
> Also, is u-boot touching PLLH or anything related to HDMI?

Since u-boot needs to enable USB and a console via HDMI this is possible. But this is done via mailbox to the VideoCore firmware, so i can't provide any helpful information [1].

Compared the sysfs regdumps for the following clocks, but didn't see any difference:
vpu
pllh
pllh_pix_prediv

Thanks
Stefan

[1] - https://elixir.bootlin.com/u-boot/latest/source/arch/arm/mach-bcm283x/msg.c

> 
> [1]https://patchwork.kernel.org/patch/10207159/
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Re: [BUG] drm/vc4: vblank wait timed out

[Stefan Wahren]

Hi Stefan,

> Stefan Schake <stschake@gmail.com> hat am 5. Mai 2018 um 19:29 geschrieben:
> 
> 
> On Sat, May 5, 2018 at 1:47 PM, Stefan Wahren <stefan.wahren@i2se.com> wrote:
> > Hi,
> >
> > after submit of the latest bcm2835 clock fixes, i thought this issue has been fixed. But i've seen this issue with current mainline 4.17-rc3 (bcm2835_defconfig) on Raspberry Pi 1 B (using U-Boot TFTP Boot). Strangly i couldn't reproduce this issue with same kernel but using only the Foundation bootloader (without U-Boot TFTP Boot).
> >
> > U-Boot version: 2018.03
> >
> > I triggered the warning using my HDMI switch:
> >
> > [  198.304572] ------------[ cut here ]------------
> > [  198.304693] WARNING: CPU: 0 PID: 10 at drivers/gpu/drm/drm_atomic_helper.c:1351 drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0
> > [  198.304703] [CRTC:68:crtc-2] vblank wait timed out
> > [  198.304751] Modules linked in: bcm2835_rng rng_core vchiq(C)
> > [  198.304790] CPU: 0 PID: 10 Comm: kworker/0:1 Tainted: G         C        4.17.0-rc3+ #1
> > [  198.304796] Hardware name: BCM2835
> > [  198.304817] Workqueue: events output_poll_execute
> > [  198.304867] [<c010f8d8>] (unwind_backtrace) from [<c010cda4>] (show_stack+0x20/0x24)
> > [  198.304934] [<c010cda4>] (show_stack) from [<c079ae74>] (dump_stack+0x20/0x28)
> > [  198.304971] [<c079ae74>] (dump_stack) from [<c011e61c>] (__warn+0xec/0x104)
> > [  198.305012] [<c011e61c>] (__warn) from [<c011e67c>] (warn_slowpath_fmt+0x48/0x50)
> > [  198.305048] [<c011e67c>] (warn_slowpath_fmt) from [<c0421638>] (drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0)
> > [  198.305098] [<c0421638>] (drm_atomic_helper_wait_for_vblanks) from [<c0455ce8>] (vc4_atomic_complete_commit+0x80/0xb8)
> > [  198.305144] [<c0455ce8>] (vc4_atomic_complete_commit) from [<c0455e30>] (vc4_atomic_commit+0x110/0x11c)
> > [  198.305174] [<c0455e30>] (vc4_atomic_commit) from [<c043dbac>] (drm_atomic_commit+0x50/0x60)
> > [  198.305202] [<c043dbac>] (drm_atomic_commit) from [<c04251e4>] (restore_fbdev_mode_atomic+0x80/0x1cc)
> > [  198.305228] [<c04251e4>] (restore_fbdev_mode_atomic) from [<c0426a8c>] (restore_fbdev_mode+0x38/0x144)
> > [  198.305270] [<c0426a8c>] (restore_fbdev_mode) from [<c0427fa8>] (drm_fb_helper_restore_fbdev_mode_unlocked+0x58/0x8c)
> > [  198.305296] [<c0427fa8>] (drm_fb_helper_restore_fbdev_mode_unlocked) from [<c0428030>] (drm_fb_helper_set_par+0x54/0x60)
> > [  198.305320] [<c0428030>] (drm_fb_helper_set_par) from [<c0427f44>] (drm_fb_helper_hotplug_event+0xc8/0xd4)
> > [  198.305343] [<c0427f44>] (drm_fb_helper_hotplug_event) from [<c0428078>] (drm_fb_helper_output_poll_changed+0x1c/0x20)
> > [  198.305382] [<c0428078>] (drm_fb_helper_output_poll_changed) from [<c0419494>] (drm_kms_helper_hotplug_event+0x34/0x38)
> > [  198.305409] [<c0419494>] (drm_kms_helper_hotplug_event) from [<c041963c>] (output_poll_execute+0x16c/0x17c)
> > [  198.305440] [<c041963c>] (output_poll_execute) from [<c01337e4>] (process_one_work+0x1e0/0x368)
> > [  198.305466] [<c01337e4>] (process_one_work) from [<c0134620>] (worker_thread+0x2a0/0x418)
> > [  198.305511] [<c0134620>] (worker_thread) from [<c0138fa8>] (kthread+0x144/0x15c)
> > [  198.305539] [<c0138fa8>] (kthread) from [<c01010e8>] (ret_from_fork+0x14/0x2c)
> > [  198.305549] Exception stack(0xc9939fb0 to 0xc9939ff8)
> > [  198.305562] 9fa0:                                     00000000 00000000 00000000 00000000
> > [  198.305578] 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> > [  198.305591] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> > [  198.305630] ---[ end trace 9c4071c657268b83 ]---
> >
> > I also dumped clk_summary in both cases, but they were identical.
> >
> > Are their any helpful information, which i can provide?
> >
> > Best regards
> > Stefan
> 
> I have seen this happen with one of those cheap Waveshare HDMI displays.
> More often when connecting its power to the RPi versus on a separate
> supply. Goes away when using a real, proper HDMI display. They come with
> bad EDID data so I pretty much just blamed the display at the time.
> 
> Does this happen during a switch and whats on the other end?

The issue happens only in combination with U-Boot. If i switch the source between my PC and the RPi then sometimes the warning is triggered.

VPU firmware: 2018-04-16
Display: HP ZR2440w

> 
> Thanks,
> Stefan
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Re: [BUG] drm/vc4: vblank wait timed out

[Boris Brezillon]

On Sat, 5 May 2018 19:44:57 +0200 (CEST)
Stefan Wahren <stefan.wahren@i2se.com> wrote:

> Hi Stefan,
> 
> > Stefan Schake <stschake@gmail.com> hat am 5. Mai 2018 um 19:29
> > geschrieben:
> > 
> > 
> > On Sat, May 5, 2018 at 1:47 PM, Stefan Wahren
> > <stefan.wahren@i2se.com> wrote:  
> > > Hi,
> > >
> > > after submit of the latest bcm2835 clock fixes, i thought this
> > > issue has been fixed. But i've seen this issue with current
> > > mainline 4.17-rc3 (bcm2835_defconfig) on Raspberry Pi 1 B (using
> > > U-Boot TFTP Boot). Strangly i couldn't reproduce this issue with
> > > same kernel but using only the Foundation bootloader (without
> > > U-Boot TFTP Boot).
> > >
> > > U-Boot version: 2018.03
> > >
> > > I triggered the warning using my HDMI switch:
> > >
> > > [  198.304572] ------------[ cut here ]------------
> > > [  198.304693] WARNING: CPU: 0 PID: 10 at
> > > drivers/gpu/drm/drm_atomic_helper.c:1351
> > > drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0 [  198.304703]
> > > [CRTC:68:crtc-2] vblank wait timed out [  198.304751] Modules
> > > linked in: bcm2835_rng rng_core vchiq(C) [  198.304790] CPU: 0
> > > PID: 10 Comm: kworker/0:1 Tainted: G         C        4.17.0-rc3+
> > > #1 [  198.304796] Hardware name: BCM2835 [  198.304817]
> > > Workqueue: events output_poll_execute [  198.304867] [<c010f8d8>]
> > > (unwind_backtrace) from [<c010cda4>] (show_stack+0x20/0x24)
> > > [  198.304934] [<c010cda4>] (show_stack) from [<c079ae74>]
> > > (dump_stack+0x20/0x28) [  198.304971] [<c079ae74>] (dump_stack)
> > > from [<c011e61c>] (__warn+0xec/0x104) [  198.305012] [<c011e61c>]
> > > (__warn) from [<c011e67c>] (warn_slowpath_fmt+0x48/0x50)
> > > [  198.305048] [<c011e67c>] (warn_slowpath_fmt) from [<c0421638>]
> > > (drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0) [  198.305098]
> > > [<c0421638>] (drm_atomic_helper_wait_for_vblanks) from
> > > [<c0455ce8>] (vc4_atomic_complete_commit+0x80/0xb8)
> > > [  198.305144] [<c0455ce8>] (vc4_atomic_complete_commit) from
> > > [<c0455e30>] (vc4_atomic_commit+0x110/0x11c) [  198.305174]
> > > [<c0455e30>] (vc4_atomic_commit) from [<c043dbac>]
> > > (drm_atomic_commit+0x50/0x60) [  198.305202] [<c043dbac>]
> > > (drm_atomic_commit) from [<c04251e4>]
> > > (restore_fbdev_mode_atomic+0x80/0x1cc) [  198.305228]
> > > [<c04251e4>] (restore_fbdev_mode_atomic) from [<c0426a8c>]
> > > (restore_fbdev_mode+0x38/0x144) [  198.305270] [<c0426a8c>]
> > > (restore_fbdev_mode) from [<c0427fa8>]
> > > (drm_fb_helper_restore_fbdev_mode_unlocked+0x58/0x8c)
> > > [  198.305296] [<c0427fa8>]
> > > (drm_fb_helper_restore_fbdev_mode_unlocked) from [<c0428030>]
> > > (drm_fb_helper_set_par+0x54/0x60) [  198.305320] [<c0428030>]
> > > (drm_fb_helper_set_par) from [<c0427f44>]
> > > (drm_fb_helper_hotplug_event+0xc8/0xd4) [  198.305343]
> > > [<c0427f44>] (drm_fb_helper_hotplug_event) from [<c0428078>]
> > > (drm_fb_helper_output_poll_changed+0x1c/0x20) [  198.305382]
> > > [<c0428078>] (drm_fb_helper_output_poll_changed) from
> > > [<c0419494>] (drm_kms_helper_hotplug_event+0x34/0x38)
> > > [  198.305409] [<c0419494>] (drm_kms_helper_hotplug_event) from
> > > [<c041963c>] (output_poll_execute+0x16c/0x17c) [  198.305440]
> > > [<c041963c>] (output_poll_execute) from [<c01337e4>]
> > > (process_one_work+0x1e0/0x368) [  198.305466] [<c01337e4>]
> > > (process_one_work) from [<c0134620>] (worker_thread+0x2a0/0x418)
> > > [  198.305511] [<c0134620>] (worker_thread) from [<c0138fa8>]
> > > (kthread+0x144/0x15c) [  198.305539] [<c0138fa8>] (kthread) from
> > > [<c01010e8>] (ret_from_fork+0x14/0x2c) [  198.305549] Exception
> > > stack(0xc9939fb0 to 0xc9939ff8) [  198.305562]
> > > 9fa0:                                     00000000 00000000
> > > 00000000 00000000 [  198.305578] 9fc0: 00000000 00000000 00000000
> > > 00000000 00000000 00000000 00000000 00000000 [  198.305591] 9fe0:
> > > 00000000 00000000 00000000 00000000 00000013 00000000
> > > [  198.305630] ---[ end trace 9c4071c657268b83 ]---
> > >
> > > I also dumped clk_summary in both cases, but they were identical.
> > >
> > > Are their any helpful information, which i can provide?
> > >
> > > Best regards
> > > Stefan  
> > 
> > I have seen this happen with one of those cheap Waveshare HDMI
> > displays. More often when connecting its power to the RPi versus on
> > a separate supply. Goes away when using a real, proper HDMI
> > display. They come with bad EDID data so I pretty much just blamed
> > the display at the time.
> > 
> > Does this happen during a switch and whats on the other end?  
> 
> The issue happens only in combination with U-Boot. If i switch the
> source between my PC and the RPi then sometimes the warning is
> triggered.

Is it working despite the WARN backtrace, or do you then get a black
screen? You say sometimes, that means sometimes it works, right? Also,
do you remember the mode (resolution+refresh-rate) you're using?
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Re: [BUG] drm/vc4: vblank wait timed out

[Stefan Wahren]

> Boris Brezillon <boris.brezillon@bootlin.com> hat am 5. Mai 2018 um 20:00 geschrieben:
> 
> 
> On Sat, 5 May 2018 19:44:57 +0200 (CEST)
> Stefan Wahren <stefan.wahren@i2se.com> wrote:
> 
> > Hi Stefan,
> > 
> > > Stefan Schake <stschake@gmail.com> hat am 5. Mai 2018 um 19:29
> > > geschrieben:
> > > 
> > > 
> > > On Sat, May 5, 2018 at 1:47 PM, Stefan Wahren
> > > <stefan.wahren@i2se.com> wrote:  
> > > > Hi,
> > > >
> > > > after submit of the latest bcm2835 clock fixes, i thought this
> > > > issue has been fixed. But i've seen this issue with current
> > > > mainline 4.17-rc3 (bcm2835_defconfig) on Raspberry Pi 1 B (using
> > > > U-Boot TFTP Boot). Strangly i couldn't reproduce this issue with
> > > > same kernel but using only the Foundation bootloader (without
> > > > U-Boot TFTP Boot).
> > > >
> > > > U-Boot version: 2018.03
> > > >
> > > > I triggered the warning using my HDMI switch:
> > > >
> > > > [  198.304572] ------------[ cut here ]------------
> > > > [  198.304693] WARNING: CPU: 0 PID: 10 at
> > > > drivers/gpu/drm/drm_atomic_helper.c:1351
> > > > drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0 [  198.304703]
> > > > [CRTC:68:crtc-2] vblank wait timed out [  198.304751] Modules
> > > > linked in: bcm2835_rng rng_core vchiq(C) [  198.304790] CPU: 0
> > > > PID: 10 Comm: kworker/0:1 Tainted: G         C        4.17.0-rc3+
> > > > #1 [  198.304796] Hardware name: BCM2835 [  198.304817]
> > > > Workqueue: events output_poll_execute [  198.304867] [<c010f8d8>]
> > > > (unwind_backtrace) from [<c010cda4>] (show_stack+0x20/0x24)
> > > > [  198.304934] [<c010cda4>] (show_stack) from [<c079ae74>]
> > > > (dump_stack+0x20/0x28) [  198.304971] [<c079ae74>] (dump_stack)
> > > > from [<c011e61c>] (__warn+0xec/0x104) [  198.305012] [<c011e61c>]
> > > > (__warn) from [<c011e67c>] (warn_slowpath_fmt+0x48/0x50)
> > > > [  198.305048] [<c011e67c>] (warn_slowpath_fmt) from [<c0421638>]
> > > > (drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0) [  198.305098]
> > > > [<c0421638>] (drm_atomic_helper_wait_for_vblanks) from
> > > > [<c0455ce8>] (vc4_atomic_complete_commit+0x80/0xb8)
> > > > [  198.305144] [<c0455ce8>] (vc4_atomic_complete_commit) from
> > > > [<c0455e30>] (vc4_atomic_commit+0x110/0x11c) [  198.305174]
> > > > [<c0455e30>] (vc4_atomic_commit) from [<c043dbac>]
> > > > (drm_atomic_commit+0x50/0x60) [  198.305202] [<c043dbac>]
> > > > (drm_atomic_commit) from [<c04251e4>]
> > > > (restore_fbdev_mode_atomic+0x80/0x1cc) [  198.305228]
> > > > [<c04251e4>] (restore_fbdev_mode_atomic) from [<c0426a8c>]
> > > > (restore_fbdev_mode+0x38/0x144) [  198.305270] [<c0426a8c>]
> > > > (restore_fbdev_mode) from [<c0427fa8>]
> > > > (drm_fb_helper_restore_fbdev_mode_unlocked+0x58/0x8c)
> > > > [  198.305296] [<c0427fa8>]
> > > > (drm_fb_helper_restore_fbdev_mode_unlocked) from [<c0428030>]
> > > > (drm_fb_helper_set_par+0x54/0x60) [  198.305320] [<c0428030>]
> > > > (drm_fb_helper_set_par) from [<c0427f44>]
> > > > (drm_fb_helper_hotplug_event+0xc8/0xd4) [  198.305343]
> > > > [<c0427f44>] (drm_fb_helper_hotplug_event) from [<c0428078>]
> > > > (drm_fb_helper_output_poll_changed+0x1c/0x20) [  198.305382]
> > > > [<c0428078>] (drm_fb_helper_output_poll_changed) from
> > > > [<c0419494>] (drm_kms_helper_hotplug_event+0x34/0x38)
> > > > [  198.305409] [<c0419494>] (drm_kms_helper_hotplug_event) from
> > > > [<c041963c>] (output_poll_execute+0x16c/0x17c) [  198.305440]
> > > > [<c041963c>] (output_poll_execute) from [<c01337e4>]
> > > > (process_one_work+0x1e0/0x368) [  198.305466] [<c01337e4>]
> > > > (process_one_work) from [<c0134620>] (worker_thread+0x2a0/0x418)
> > > > [  198.305511] [<c0134620>] (worker_thread) from [<c0138fa8>]
> > > > (kthread+0x144/0x15c) [  198.305539] [<c0138fa8>] (kthread) from
> > > > [<c01010e8>] (ret_from_fork+0x14/0x2c) [  198.305549] Exception
> > > > stack(0xc9939fb0 to 0xc9939ff8) [  198.305562]
> > > > 9fa0:                                     00000000 00000000
> > > > 00000000 00000000 [  198.305578] 9fc0: 00000000 00000000 00000000
> > > > 00000000 00000000 00000000 00000000 00000000 [  198.305591] 9fe0:
> > > > 00000000 00000000 00000000 00000000 00000013 00000000
> > > > [  198.305630] ---[ end trace 9c4071c657268b83 ]---
> > > >
> > > > I also dumped clk_summary in both cases, but they were identical.
> > > >
> > > > Are their any helpful information, which i can provide?
> > > >
> > > > Best regards
> > > > Stefan  
> > > 
> > > I have seen this happen with one of those cheap Waveshare HDMI
> > > displays. More often when connecting its power to the RPi versus on
> > > a separate supply. Goes away when using a real, proper HDMI
> > > display. They come with bad EDID data so I pretty much just blamed
> > > the display at the time.
> > > 
> > > Does this happen during a switch and whats on the other end?  
> > 
> > The issue happens only in combination with U-Boot. If i switch the
> > source between my PC and the RPi then sometimes the warning is
> > triggered.
> 
> Is it working despite the WARN backtrace, or do you then get a black
> screen?

It always works, but sometimes the screen stays a little bit (~ 6 secs) longer black before the console appears.

> You say sometimes, that means sometimes it works, right? 

It works always, the sometimes refers to the warning.

> Also,
> do you remember the mode (resolution+refresh-rate) you're using?

1920 x 1080 @ 60 Hz
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Re: [BUG] drm/vc4: vblank wait timed out

[Boris Brezillon]

On Sun, 6 May 2018 01:56:36 +0200 (CEST)
Stefan Wahren <stefan.wahren@i2se.com> wrote:

> > Boris Brezillon <boris.brezillon@bootlin.com> hat am 5. Mai 2018 um 20:00 geschrieben:
> > 
> > 
> > On Sat, 5 May 2018 19:44:57 +0200 (CEST)
> > Stefan Wahren <stefan.wahren@i2se.com> wrote:
> >   
> > > Hi Stefan,
> > >   
> > > > Stefan Schake <stschake@gmail.com> hat am 5. Mai 2018 um 19:29
> > > > geschrieben:
> > > > 
> > > > 
> > > > On Sat, May 5, 2018 at 1:47 PM, Stefan Wahren
> > > > <stefan.wahren@i2se.com> wrote:    
> > > > > Hi,
> > > > >
> > > > > after submit of the latest bcm2835 clock fixes, i thought this
> > > > > issue has been fixed. But i've seen this issue with current
> > > > > mainline 4.17-rc3 (bcm2835_defconfig) on Raspberry Pi 1 B (using
> > > > > U-Boot TFTP Boot). Strangly i couldn't reproduce this issue with
> > > > > same kernel but using only the Foundation bootloader (without
> > > > > U-Boot TFTP Boot).
> > > > >
> > > > > U-Boot version: 2018.03
> > > > >
> > > > > I triggered the warning using my HDMI switch:
> > > > >
> > > > > [  198.304572] ------------[ cut here ]------------
> > > > > [  198.304693] WARNING: CPU: 0 PID: 10 at
> > > > > drivers/gpu/drm/drm_atomic_helper.c:1351
> > > > > drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0 [  198.304703]
> > > > > [CRTC:68:crtc-2] vblank wait timed out [  198.304751] Modules
> > > > > linked in: bcm2835_rng rng_core vchiq(C) [  198.304790] CPU: 0
> > > > > PID: 10 Comm: kworker/0:1 Tainted: G         C        4.17.0-rc3+
> > > > > #1 [  198.304796] Hardware name: BCM2835 [  198.304817]
> > > > > Workqueue: events output_poll_execute [  198.304867] [<c010f8d8>]
> > > > > (unwind_backtrace) from [<c010cda4>] (show_stack+0x20/0x24)
> > > > > [  198.304934] [<c010cda4>] (show_stack) from [<c079ae74>]
> > > > > (dump_stack+0x20/0x28) [  198.304971] [<c079ae74>] (dump_stack)
> > > > > from [<c011e61c>] (__warn+0xec/0x104) [  198.305012] [<c011e61c>]
> > > > > (__warn) from [<c011e67c>] (warn_slowpath_fmt+0x48/0x50)
> > > > > [  198.305048] [<c011e67c>] (warn_slowpath_fmt) from [<c0421638>]
> > > > > (drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0) [  198.305098]
> > > > > [<c0421638>] (drm_atomic_helper_wait_for_vblanks) from
> > > > > [<c0455ce8>] (vc4_atomic_complete_commit+0x80/0xb8)
> > > > > [  198.305144] [<c0455ce8>] (vc4_atomic_complete_commit) from
> > > > > [<c0455e30>] (vc4_atomic_commit+0x110/0x11c) [  198.305174]
> > > > > [<c0455e30>] (vc4_atomic_commit) from [<c043dbac>]
> > > > > (drm_atomic_commit+0x50/0x60) [  198.305202] [<c043dbac>]
> > > > > (drm_atomic_commit) from [<c04251e4>]
> > > > > (restore_fbdev_mode_atomic+0x80/0x1cc) [  198.305228]
> > > > > [<c04251e4>] (restore_fbdev_mode_atomic) from [<c0426a8c>]
> > > > > (restore_fbdev_mode+0x38/0x144) [  198.305270] [<c0426a8c>]
> > > > > (restore_fbdev_mode) from [<c0427fa8>]
> > > > > (drm_fb_helper_restore_fbdev_mode_unlocked+0x58/0x8c)
> > > > > [  198.305296] [<c0427fa8>]
> > > > > (drm_fb_helper_restore_fbdev_mode_unlocked) from [<c0428030>]
> > > > > (drm_fb_helper_set_par+0x54/0x60) [  198.305320] [<c0428030>]
> > > > > (drm_fb_helper_set_par) from [<c0427f44>]
> > > > > (drm_fb_helper_hotplug_event+0xc8/0xd4) [  198.305343]
> > > > > [<c0427f44>] (drm_fb_helper_hotplug_event) from [<c0428078>]
> > > > > (drm_fb_helper_output_poll_changed+0x1c/0x20) [  198.305382]
> > > > > [<c0428078>] (drm_fb_helper_output_poll_changed) from
> > > > > [<c0419494>] (drm_kms_helper_hotplug_event+0x34/0x38)
> > > > > [  198.305409] [<c0419494>] (drm_kms_helper_hotplug_event) from
> > > > > [<c041963c>] (output_poll_execute+0x16c/0x17c) [  198.305440]
> > > > > [<c041963c>] (output_poll_execute) from [<c01337e4>]
> > > > > (process_one_work+0x1e0/0x368) [  198.305466] [<c01337e4>]
> > > > > (process_one_work) from [<c0134620>] (worker_thread+0x2a0/0x418)
> > > > > [  198.305511] [<c0134620>] (worker_thread) from [<c0138fa8>]
> > > > > (kthread+0x144/0x15c) [  198.305539] [<c0138fa8>] (kthread) from
> > > > > [<c01010e8>] (ret_from_fork+0x14/0x2c) [  198.305549] Exception
> > > > > stack(0xc9939fb0 to 0xc9939ff8) [  198.305562]
> > > > > 9fa0:                                     00000000 00000000
> > > > > 00000000 00000000 [  198.305578] 9fc0: 00000000 00000000 00000000
> > > > > 00000000 00000000 00000000 00000000 00000000 [  198.305591] 9fe0:
> > > > > 00000000 00000000 00000000 00000000 00000013 00000000
> > > > > [  198.305630] ---[ end trace 9c4071c657268b83 ]---
> > > > >
> > > > > I also dumped clk_summary in both cases, but they were identical.
> > > > >
> > > > > Are their any helpful information, which i can provide?
> > > > >
> > > > > Best regards
> > > > > Stefan    
> > > > 
> > > > I have seen this happen with one of those cheap Waveshare HDMI
> > > > displays. More often when connecting its power to the RPi versus on
> > > > a separate supply. Goes away when using a real, proper HDMI
> > > > display. They come with bad EDID data so I pretty much just blamed
> > > > the display at the time.
> > > > 
> > > > Does this happen during a switch and whats on the other end?    
> > > 
> > > The issue happens only in combination with U-Boot. If i switch the
> > > source between my PC and the RPi then sometimes the warning is
> > > triggered.

Okay, can you dump HDMI and clk regs in both situations (u-boot and the
Foundation bootloader)? There's probably a slight difference that makes
it work in one case and not the other.

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Re: [BUG] drm/vc4: vblank wait timed out

[Stefan Wahren]

Hi Boris,

> Boris Brezillon <boris.brezillon@bootlin.com> hat am 7. Mai 2018 um 09:11 geschrieben:
> 
> 
> On Sun, 6 May 2018 01:56:36 +0200 (CEST)
> Stefan Wahren <stefan.wahren@i2se.com> wrote:
> 
> > > Boris Brezillon <boris.brezillon@bootlin.com> hat am 5. Mai 2018 um 20:00 geschrieben:
> > > 
> > > 
> > > On Sat, 5 May 2018 19:44:57 +0200 (CEST)
> > > Stefan Wahren <stefan.wahren@i2se.com> wrote:
> > >   
> > > > Hi Stefan,
> > > >   
> > > > > Stefan Schake <stschake@gmail.com> hat am 5. Mai 2018 um 19:29
> > > > > geschrieben:
> > > > > 
> > > > > 
> > > > > On Sat, May 5, 2018 at 1:47 PM, Stefan Wahren
> > > > > <stefan.wahren@i2se.com> wrote:    
> > > > > > Hi,
> > > > > >
> > > > > > after submit of the latest bcm2835 clock fixes, i thought this
> > > > > > issue has been fixed. But i've seen this issue with current
> > > > > > mainline 4.17-rc3 (bcm2835_defconfig) on Raspberry Pi 1 B (using
> > > > > > U-Boot TFTP Boot). Strangly i couldn't reproduce this issue with
> > > > > > same kernel but using only the Foundation bootloader (without
> > > > > > U-Boot TFTP Boot).
> > > > > >
> > > > > > U-Boot version: 2018.03
> > > > > >
> > > > > > I triggered the warning using my HDMI switch:
> > > > > >
> > > > > > [  198.304572] ------------[ cut here ]------------
> > > > > > [  198.304693] WARNING: CPU: 0 PID: 10 at
> > > > > > drivers/gpu/drm/drm_atomic_helper.c:1351
> > > > > > drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0 [  198.304703]
> > > > > > [CRTC:68:crtc-2] vblank wait timed out [  198.304751] Modules
> > > > > > linked in: bcm2835_rng rng_core vchiq(C) [  198.304790] CPU: 0
> > > > > > PID: 10 Comm: kworker/0:1 Tainted: G         C        4.17.0-rc3+
> > > > > > #1 [  198.304796] Hardware name: BCM2835 [  198.304817]
> > > > > > Workqueue: events output_poll_execute [  198.304867] [<c010f8d8>]
> > > > > > (unwind_backtrace) from [<c010cda4>] (show_stack+0x20/0x24)
> > > > > > [  198.304934] [<c010cda4>] (show_stack) from [<c079ae74>]
> > > > > > (dump_stack+0x20/0x28) [  198.304971] [<c079ae74>] (dump_stack)
> > > > > > from [<c011e61c>] (__warn+0xec/0x104) [  198.305012] [<c011e61c>]
> > > > > > (__warn) from [<c011e67c>] (warn_slowpath_fmt+0x48/0x50)
> > > > > > [  198.305048] [<c011e67c>] (warn_slowpath_fmt) from [<c0421638>]
> > > > > > (drm_atomic_helper_wait_for_vblanks+0x1d4/0x1f0) [  198.305098]
> > > > > > [<c0421638>] (drm_atomic_helper_wait_for_vblanks) from
> > > > > > [<c0455ce8>] (vc4_atomic_complete_commit+0x80/0xb8)
> > > > > > [  198.305144] [<c0455ce8>] (vc4_atomic_complete_commit) from
> > > > > > [<c0455e30>] (vc4_atomic_commit+0x110/0x11c) [  198.305174]
> > > > > > [<c0455e30>] (vc4_atomic_commit) from [<c043dbac>]
> > > > > > (drm_atomic_commit+0x50/0x60) [  198.305202] [<c043dbac>]
> > > > > > (drm_atomic_commit) from [<c04251e4>]
> > > > > > (restore_fbdev_mode_atomic+0x80/0x1cc) [  198.305228]
> > > > > > [<c04251e4>] (restore_fbdev_mode_atomic) from [<c0426a8c>]
> > > > > > (restore_fbdev_mode+0x38/0x144) [  198.305270] [<c0426a8c>]
> > > > > > (restore_fbdev_mode) from [<c0427fa8>]
> > > > > > (drm_fb_helper_restore_fbdev_mode_unlocked+0x58/0x8c)
> > > > > > [  198.305296] [<c0427fa8>]
> > > > > > (drm_fb_helper_restore_fbdev_mode_unlocked) from [<c0428030>]
> > > > > > (drm_fb_helper_set_par+0x54/0x60) [  198.305320] [<c0428030>]
> > > > > > (drm_fb_helper_set_par) from [<c0427f44>]
> > > > > > (drm_fb_helper_hotplug_event+0xc8/0xd4) [  198.305343]
> > > > > > [<c0427f44>] (drm_fb_helper_hotplug_event) from [<c0428078>]
> > > > > > (drm_fb_helper_output_poll_changed+0x1c/0x20) [  198.305382]
> > > > > > [<c0428078>] (drm_fb_helper_output_poll_changed) from
> > > > > > [<c0419494>] (drm_kms_helper_hotplug_event+0x34/0x38)
> > > > > > [  198.305409] [<c0419494>] (drm_kms_helper_hotplug_event) from
> > > > > > [<c041963c>] (output_poll_execute+0x16c/0x17c) [  198.305440]
> > > > > > [<c041963c>] (output_poll_execute) from [<c01337e4>]
> > > > > > (process_one_work+0x1e0/0x368) [  198.305466] [<c01337e4>]
> > > > > > (process_one_work) from [<c0134620>] (worker_thread+0x2a0/0x418)
> > > > > > [  198.305511] [<c0134620>] (worker_thread) from [<c0138fa8>]
> > > > > > (kthread+0x144/0x15c) [  198.305539] [<c0138fa8>] (kthread) from
> > > > > > [<c01010e8>] (ret_from_fork+0x14/0x2c) [  198.305549] Exception
> > > > > > stack(0xc9939fb0 to 0xc9939ff8) [  198.305562]
> > > > > > 9fa0:                                     00000000 00000000
> > > > > > 00000000 00000000 [  198.305578] 9fc0: 00000000 00000000 00000000
> > > > > > 00000000 00000000 00000000 00000000 00000000 [  198.305591] 9fe0:
> > > > > > 00000000 00000000 00000000 00000000 00000013 00000000
> > > > > > [  198.305630] ---[ end trace 9c4071c657268b83 ]---
> > > > > >
> > > > > > I also dumped clk_summary in both cases, but they were identical.
> > > > > >
> > > > > > Are their any helpful information, which i can provide?
> > > > > >
> > > > > > Best regards
> > > > > > Stefan    
> > > > > 
> > > > > I have seen this happen with one of those cheap Waveshare HDMI
> > > > > displays. More often when connecting its power to the RPi versus on
> > > > > a separate supply. Goes away when using a real, proper HDMI
> > > > > display. They come with bad EDID data so I pretty much just blamed
> > > > > the display at the time.
> > > > > 
> > > > > Does this happen during a switch and whats on the other end?    
> > > > 
> > > > The issue happens only in combination with U-Boot. If i switch the
> > > > source between my PC and the RPi then sometimes the warning is
> > > > triggered.
> 
> Okay, can you dump HDMI and clk regs in both situations (u-boot and the
> Foundation bootloader)? There's probably a slight difference that makes
> it work in one case and not the other.
>

sorry, i didn't tried long enough. Today i was able to reproduce the timeout even without U-Boot. So there is no difference.

Here is the dump with Kernel 4.17rc4 (bcm2835) and U-Boot:

https://gist.github.com/lategoodbye/84f322357f311a5cd232f38b57c11cd4

Regards
Stefan
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