[PATCH RESEND 2/2] drm: bridge: adv7511: unregister cec i2c device after cec adapter

[Robert Foss]

On Sun, 12 Jun 2022 at 16:49, Alvin Šipraga <alvin at pqrs.dk> wrote:
>
> From: Alvin Šipraga <alsi at bang-olufsen.dk>
>
> cec_unregister_adapter() assumes that the underlying adapter ops are
> callable. For example, if the CEC adapter currently has a valid physical
> address, then the unregistration procedure will invalidate the physical
> address by setting it to f.f.f.f. Whence the following kernel oops
> observed after removing the adv7511 module:
>
>     Unable to handle kernel execution of user memory at virtual address 0000000000000000
>     Internal error: Oops: 86000004 [#1] PREEMPT_RT SMP
>     Call trace:
>      0x0
>      adv7511_cec_adap_log_addr+0x1ac/0x1c8 [adv7511]
>      cec_adap_unconfigure+0x44/0x90 [cec]
>      __cec_s_phys_addr.part.0+0x68/0x230 [cec]
>      __cec_s_phys_addr+0x40/0x50 [cec]
>      cec_unregister_adapter+0xb4/0x118 [cec]
>      adv7511_remove+0x60/0x90 [adv7511]
>      i2c_device_remove+0x34/0xe0
>      device_release_driver_internal+0x114/0x1f0
>      driver_detach+0x54/0xe0
>      bus_remove_driver+0x60/0xd8
>      driver_unregister+0x34/0x60
>      i2c_del_driver+0x2c/0x68
>      adv7511_exit+0x1c/0x67c [adv7511]
>      __arm64_sys_delete_module+0x154/0x288
>      invoke_syscall+0x48/0x100
>      el0_svc_common.constprop.0+0x48/0xe8
>      do_el0_svc+0x28/0x88
>      el0_svc+0x1c/0x50
>      el0t_64_sync_handler+0xa8/0xb0
>      el0t_64_sync+0x15c/0x160
>     Code: bad PC value
>     ---[ end trace 0000000000000000 ]---
>
> Protect against this scenario by unregistering i2c_cec after
> unregistering the CEC adapter. Duly disable the CEC clock afterwards
> too.
>
> Fixes: 3b1b975003e4 ("drm: adv7511/33: add HDMI CEC support")
> Signed-off-by: Alvin Šipraga <alsi at bang-olufsen.dk>
> ---
>  drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> index 5bb9300040dd..023c0ad132e0 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> @@ -1339,9 +1339,6 @@ static int adv7511_remove(struct i2c_client *i2c)
>  {
>         struct adv7511 *adv7511 = i2c_get_clientdata(i2c);
>
> -       i2c_unregister_device(adv7511->i2c_cec);
> -       clk_disable_unprepare(adv7511->cec_clk);
> -
>         adv7511_uninit_regulators(adv7511);
>
>         drm_bridge_remove(&adv7511->bridge);
> @@ -1349,6 +1346,8 @@ static int adv7511_remove(struct i2c_client *i2c)
>         adv7511_audio_exit(adv7511);
>
>         cec_unregister_adapter(adv7511->cec_adap);
> +       i2c_unregister_device(adv7511->i2c_cec);
> +       clk_disable_unprepare(adv7511->cec_clk);
>
>         i2c_unregister_device(adv7511->i2c_packet);
>         i2c_unregister_device(adv7511->i2c_edid);
> --
> 2.36.1
>

Reviewed-by: Robert Foss <robert.foss at linaro.org>