linux-kernel - Re: [PATCH] drm/tilcdc: Fix removal actions in case of failed probe

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Message-ID: <p4u2goyadub3dfuz4empf3g7a44b2ausy4hjjkcwj7nzgeochx@xztpij2i2lao>
Date: Tue, 14 Oct 2025 17:36:47 +0200
From: Maxime Ripard <mripard@...nel.org>
To: Kory Maincent <kory.maincent@...tlin.com>
Cc: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, 
	Douglas Anderson <dianders@...omium.org>, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	Bajjuri Praneeth <praneeth@...com>, Louis Chauvet <louis.chauvet@...tlin.com>, 
	thomas.petazzoni@...tlin.com, Jyri Sarha <jyri.sarha@....fi>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Subject: Re: [PATCH] drm/tilcdc: Fix removal actions in case of failed probe

On Tue, Oct 14, 2025 at 04:32:28PM +0200, Kory Maincent wrote:
> From: "Kory Maincent (TI.com)" <kory.maincent@...tlin.com>
> 
> The drm_kms_helper_poll_fini() and drm_atomic_helper_shutdown() helpers
> should only be called when the device has been successfully registered.
> Currently, these functions are called unconditionally in tilcdc_fini(),
> which causes warnings during probe deferral scenarios.
> 
> [    7.972317] WARNING: CPU: 0 PID: 23 at drivers/gpu/drm/drm_atomic_state_helper.c:175 drm_atomic_helper_crtc_duplicate_state+0x60/0x68
> ...
> [    8.005820]  drm_atomic_helper_crtc_duplicate_state from drm_atomic_get_crtc_state+0x68/0x108
> [    8.005858]  drm_atomic_get_crtc_state from drm_atomic_helper_disable_all+0x90/0x1c8
> [    8.005885]  drm_atomic_helper_disable_all from drm_atomic_helper_shutdown+0x90/0x144
> [    8.005911]  drm_atomic_helper_shutdown from tilcdc_fini+0x68/0xf8 [tilcdc]
> [    8.005957]  tilcdc_fini [tilcdc] from tilcdc_pdev_probe+0xb0/0x6d4 [tilcdc]
> 
> Fix this by moving both drm_kms_helper_poll_fini() and
> drm_atomic_helper_shutdown() inside the priv->is_registered conditional
> block, ensuring they only execute after successful device registration.
> 
> Fixes: 3c4babae3c4a ("drm: Call drm_atomic_helper_shutdown() at shutdown/remove time for misc drivers")
> Signed-off-by: Kory Maincent (TI.com) <kory.maincent@...tlin.com>
> ---
>  drivers/gpu/drm/tilcdc/tilcdc_drv.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.c b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
> index 7caec4d38ddf..2031267a3490 100644
> --- a/drivers/gpu/drm/tilcdc/tilcdc_drv.c
> +++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
> @@ -172,11 +172,11 @@ static void tilcdc_fini(struct drm_device *dev)
>  	if (priv->crtc)
>  		tilcdc_crtc_shutdown(priv->crtc);
>  
> -	if (priv->is_registered)
> +	if (priv->is_registered) {
>  		drm_dev_unregister(dev);
> -
> -	drm_kms_helper_poll_fini(dev);
> -	drm_atomic_helper_shutdown(dev);
> +		drm_kms_helper_poll_fini(dev);
> +		drm_atomic_helper_shutdown(dev);
> +	}
>  	tilcdc_irq_uninstall(dev);
>  	drm_mode_config_cleanup(dev);

I don't think that's the right fix. tilcdc_fini is pretty complex
because it gets called from multiple locations with various level of
initialisation.

This is done because tilcdc_init is using a bunch of deprecated
functions with better alternatives now, and those would make the job of
tilcdc_fini much easier.

That's what we should be focusing on.

Maxime

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