linux-kernel - Re: [PATCH] media/mmp: Bring back registration of the device

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Message-ID: <Z30QWA-LfZHwVbmm@kekkonen.localdomain>
Date: Tue, 7 Jan 2025 11:30:32 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Lubomir Rintel <lrintel@...hat.com>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org, Lubomir Rintel <lkundrak@...sk>,
	stable@...r.kernel.org
Subject: Re: [PATCH] media/mmp: Bring back registration of the device

Hi Lubomir,

Thanks for the patch.

On Tue, Dec 31, 2024 at 08:04:34PM +0100, Lubomir Rintel wrote:
> In commit 4af65141e38e ("media: marvell: cafe: Register V4L2 device
> earlier"), a call to v4l2_device_register() was moved away from
> mccic_register() into its caller, marvell/cafe's cafe_pci_probe().
> This is not the only caller though -- there's also marvell/mmp.
> 
> Add v4l2_device_register() into mmpcam_probe() to unbreak the MMP camera
> driver, in a fashion analogous to what's been done to the Cafe driver.
> Same for the teardown path.
> 
> Fixes: 4af65141e38e ("media: marvell: cafe: Register V4L2 device earlier")
> Signed-off-by: Lubomir Rintel <lkundrak@...sk>
> Cc: stable@...r.kernel.org # v6.6+
> ---
>  drivers/media/platform/marvell/mmp-driver.c | 21 +++++++++++++++++----
>  1 file changed, 17 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/media/platform/marvell/mmp-driver.c b/drivers/media/platform/marvell/mmp-driver.c
> index 3fd4fc1b9c48..d3da7ebb4a2b 100644
> --- a/drivers/media/platform/marvell/mmp-driver.c
> +++ b/drivers/media/platform/marvell/mmp-driver.c
> @@ -231,13 +231,23 @@ static int mmpcam_probe(struct platform_device *pdev)
>  
>  	mcam_init_clk(mcam);
>  
> +	/*
> +	 * Register with V4L.
> +	 */
> +
> +	ret = v4l2_device_register(mcam->dev, &mcam->v4l2_dev);

I'd do this just before initialising the notifier (as in the patch in
Fixes: tag): registering the V4L2 device requires probably severe memory
pressure while it's entirely plausible there's no endpoint for the device.

> +	if (ret)
> +		return ret;
> +
>  	/*
>  	 * Create a match of the sensor against its OF node.
>  	 */
>  	ep = fwnode_graph_get_next_endpoint(of_fwnode_handle(pdev->dev.of_node),
>  					    NULL);
> -	if (!ep)
> -		return -ENODEV;
> +	if (!ep) {
> +		ret = -ENODEV;
> +		goto out_v4l2_device_unregister;
> +	}
>  
>  	v4l2_async_nf_init(&mcam->notifier, &mcam->v4l2_dev);
>  
> @@ -246,7 +256,7 @@ static int mmpcam_probe(struct platform_device *pdev)
>  	fwnode_handle_put(ep);
>  	if (IS_ERR(asd)) {
>  		ret = PTR_ERR(asd);
> -		goto out;
> +		goto out_v4l2_device_unregister;
>  	}
>  
>  	/*
> @@ -254,7 +264,7 @@ static int mmpcam_probe(struct platform_device *pdev)
>  	 */
>  	ret = mccic_register(mcam);
>  	if (ret)
> -		goto out;
> +		goto out_v4l2_device_unregister;
>  
>  	/*
>  	 * Add OF clock provider.
> @@ -283,6 +293,8 @@ static int mmpcam_probe(struct platform_device *pdev)
>  	return 0;
>  out:

For clarity, it'd be best to rename the out label to something more
specific, i.e. out_mccic_shutdown. Either way,

Reviewed-by: Sakari Ailus <sakari.ailus@...ux.intel.com>

>  	mccic_shutdown(mcam);
> +out_v4l2_device_unregister:
> +	v4l2_device_unregister(&mcam->v4l2_dev);
>  
>  	return ret;
>  }
> @@ -293,6 +305,7 @@ static void mmpcam_remove(struct platform_device *pdev)
>  	struct mcam_camera *mcam = &cam->mcam;
>  
>  	mccic_shutdown(mcam);
> +	v4l2_device_unregister(&mcam->v4l2_dev);
>  	pm_runtime_force_suspend(mcam->dev);
>  }
>  

-- 
Regards,

Sakari Ailus