drm-misc-next: WARNING: at drivers/gpu/drm/vc4/vc4_hdmi_regs.h:487

Thu Jun 30 07:37:50 UTC 2022

Hi Stefan,

On Wed, Jun 29, 2022 at 10:50:21PM +0200, Stefan Wahren wrote:
> Hi Maxime,
> 
> i tested todays drm-misc-next 9db35bb349 with Raspberry Pi 3 B Plus
> (arm/multi_v7_defconfig, mainline DTB) and get the following warning in the
> kernel logs:
> 
> [   25.698459] vc4-drm soc:gpu: bound 3f400000.hvs (ops vc4_hvs_ops [vc4])
> [   25.698657] ------------[ cut here ]------------
> [   25.698660] WARNING: CPU: 1 PID: 153 at
> drivers/gpu/drm/vc4/vc4_hdmi_regs.h:487 vc4_hdmi_reset+0x3e0/0x4e0 [vc4]
> [   25.698757] Modules linked in: brcmutil vc4(+) snd_soc_core ac97_bus
> sha256_generic libsha256 snd_pcm_dmaengine sha256_arm snd_pcm cfg80211
> snd_timer hci_uart btbcm snd soundcore bluetooth raspberrypi_hwmon
> drm_cma_helper ecdh_generic ecc libaes bcm2835_thermal microchip lan78xx
> crc32_arm_ce
> [   25.698831] CPU: 1 PID: 153 Comm: systemd-udevd Not tainted
> 5.19.0-rc2-00085-g9db35bb349a0 #2
> [   25.698839] Hardware name: BCM2835
> [   25.698850]  unwind_backtrace from show_stack+0x10/0x14
> [   25.698866]  show_stack from dump_stack_lvl+0x40/0x4c
> [   25.698879]  dump_stack_lvl from __warn+0xcc/0x144
> [   25.698890]  __warn from warn_slowpath_fmt+0x5c/0xb4
> [   25.698900]  warn_slowpath_fmt from vc4_hdmi_reset+0x3e0/0x4e0 [vc4]
> [   25.698996]  vc4_hdmi_reset [vc4] from vc4_hdmi_runtime_resume+0x4c/0x64
> [vc4]
> [   25.699165]  vc4_hdmi_runtime_resume [vc4] from vc4_hdmi_bind+0x208/0x994
> [vc4]
> [   25.699333]  vc4_hdmi_bind [vc4] from component_bind_all+0x100/0x230
> [   25.699428]  component_bind_all from vc4_drm_bind+0x1a8/0x280 [vc4]
> [   25.699518]  vc4_drm_bind [vc4] from
> try_to_bring_up_aggregate_device+0x160/0x1bc
> [   25.699610]  try_to_bring_up_aggregate_device from
> component_master_add_with_match+0xc4/0xf8
> [   25.699622]  component_master_add_with_match from
> vc4_platform_drm_probe+0xa0/0xc0 [vc4]
> [   25.699712]  vc4_platform_drm_probe [vc4] from platform_probe+0x5c/0xbc
> [   25.699802]  platform_probe from really_probe.part.0+0x9c/0x2b0
> [   25.699812]  really_probe.part.0 from __driver_probe_device+0xa8/0x13c
> [   25.699823]  __driver_probe_device from driver_probe_device+0x34/0x108
> [   25.699834]  driver_probe_device from __driver_attach+0xb4/0x17c
> [   25.699846]  __driver_attach from bus_for_each_dev+0x70/0xb0
> [   25.699856]  bus_for_each_dev from bus_add_driver+0x164/0x1f0
> [   25.699867]  bus_add_driver from driver_register+0x88/0x11c
> [   25.699878]  driver_register from do_one_initcall+0x40/0x1d4
> [   25.699890]  do_one_initcall from do_init_module+0x44/0x1d4
> [   25.699901]  do_init_module from sys_finit_module+0xbc/0xf8
> [   25.699909]  sys_finit_module from __sys_trace_return+0x0/0x10
> [   25.699918] Exception stack(0xf568dfa8 to 0xf568dff0)
> [   25.699926] dfa0:                   6a09f700 00000000 00000016 b6dee8e0
> 00000000 b6def3f4
> [   25.699934] dfc0: 6a09f700 00000000 00000000 0000017b 0053b9a8 0052a1dc
> 0053af10 00000000
> [   25.699940] dfe0: be8e5160 be8e5150 b6de59d8 b6ed5ae0
> [   25.699944] ---[ end trace 0000000000000000 ]---
> 
> I was able to bisect the warning to the following commit:
> 
> drm/vc4: hdmi: Move HDMI reset to pm_resume
> 
> The BCM2835-37 found in the RaspberryPi 0 to 3 have a power domain
> attached to the HDMI block, handled in Linux through runtime_pm.
> 
> That power domain is shared with the VEC block, so even if we put our
> runtime_pm reference in the HDMI driver it would keep being on. If the
> VEC is disabled though, the power domain would be disabled and we would
> lose any initialization done in our bind implementation.
> 
> That initialization involves calling the reset function and initializing
> the CEC registers.
> 
> Let's move the initialization to our runtime_resume implementation so
> that we initialize everything properly if we ever need to.
> 
> Fixes: c86b41214362 ("drm/vc4: hdmi: Move the HSM clock enable to
> runtime_pm")
> Signed-off-by: Dave Stevenson <dave.stevenson at raspberrypi.com>
> Link: https://lore.kernel.org/r/20220613144800.326124-24-maxime@cerno.tech
> Signed-off-by: Maxime Ripard <maxime at cerno.tech>

Yeah, I noticed it yesterday

https://lore.kernel.org/dri-devel/20220629123510.1915022-1-maxime@cerno.tech/T/#m1027cef33d8c66a302b2b8a80bab8a9dc6652f04

and

https://lore.kernel.org/dri-devel/20220629123510.1915022-1-maxime@cerno.tech/T/#mc869819c66f7b3df8b31a320636a9172780a58e7

Should address it

Maxime
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