[PATCH 1/2] drm: rcar-du: Don't put reference to drm_device in rcar_du_remove()

[PATCH 1/2] drm: rcar-du: Don't put reference to drm_device in rcar_du_remove()

[Laurent Pinchart]

The reference to the drm_device that was acquired by
devm_drm_dev_alloc() is released automatically by the devres
infrastructure. It must not be released manually, as that causes a
reference underflow..

Fixes: ea6aae151887 ("drm: rcar-du: Embed drm_device in rcar_du_device")
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
---
 drivers/gpu/drm/rcar-du/rcar_du_drv.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.c b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
index 43de3d8686e8..2a06ec1cbefb 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_drv.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
@@ -556,8 +556,6 @@ static int rcar_du_remove(struct platform_device *pdev)
 
 	drm_kms_helper_poll_fini(ddev);
 
-	drm_dev_put(ddev);
-
 	return 0;
 }
 
-- 
Regards,

Laurent Pinchart

[PATCH 2/2] drm: rcar-du: Shutdown the display on remove

[Laurent Pinchart]

When the device is unbound from the driver (the DU being a platform
device, this occurs either when removing the DU module, or when
unbinding the device manually through sysfs), the display may be active.
Make sure it gets shut down.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
---
 drivers/gpu/drm/rcar-du/rcar_du_drv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.c b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
index 2a06ec1cbefb..9f1a3aad4dd7 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_drv.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
@@ -553,6 +553,7 @@ static int rcar_du_remove(struct platform_device *pdev)
 	struct drm_device *ddev = &rcdu->ddev;
 
 	drm_dev_unregister(ddev);
+	drm_atomic_helper_shutdown(ddev);
 
 	drm_kms_helper_poll_fini(ddev);
 
-- 
Regards,

Laurent Pinchart

Re: [PATCH 1/2] drm: rcar-du: Don't put reference to drm_device in rcar_du_remove()

[Kieran Bingham]

Hi Laurent,

On 23/03/2021 00:56, Laurent Pinchart wrote:
> The reference to the drm_device that was acquired by
> devm_drm_dev_alloc() is released automatically by the devres
> infrastructure. It must not be released manually, as that causes a
> reference underflow..
> 

Ouch. We need some tests on module load and unload somewhere...

I'm getting closer with infrastructure ...


> Fixes: ea6aae151887 ("drm: rcar-du: Embed drm_device in rcar_du_device")
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>


> ---
>  drivers/gpu/drm/rcar-du/rcar_du_drv.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.c b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> index 43de3d8686e8..2a06ec1cbefb 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> @@ -556,8 +556,6 @@ static int rcar_du_remove(struct platform_device *pdev)
>  
>  	drm_kms_helper_poll_fini(ddev);
>  
> -	drm_dev_put(ddev);
> -
>  	return 0;
>  }
>  
> 

Re: [PATCH 2/2] drm: rcar-du: Shutdown the display on remove

[Kieran Bingham]

Hi Laurent,

On 23/03/2021 00:56, Laurent Pinchart wrote:
> When the device is unbound from the driver (the DU being a platform
> device, this occurs either when removing the DU module, or when
> unbinding the device manually through sysfs), the display may be active.
> Make sure it gets shut down.

I bet this may be particularly true if there's a console on it.


> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> ---
>  drivers/gpu/drm/rcar-du/rcar_du_drv.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.c b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> index 2a06ec1cbefb..9f1a3aad4dd7 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.c
> @@ -553,6 +553,7 @@ static int rcar_du_remove(struct platform_device *pdev)
>  	struct drm_device *ddev = &rcdu->ddev;
>  
>  	drm_dev_unregister(ddev);
> +	drm_atomic_helper_shutdown(ddev);
>  
>  	drm_kms_helper_poll_fini(ddev);

There's a real mix of other drivers either calling
drm_kms_helper_poll_fini() before drm_atomic_helper_shutdown() or after,
so I'll assume that the sequencing here isn't terribly important (I hope).

So,

Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>