linux-kernel - Re: [PATCH v6 2/2] media: i2c: Add driver for ST VD56G3 camera sensor

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Message-ID: <4c8a1359-e7e3-4e1c-a159-e761ed749712@foss.st.com>
Date: Fri, 2 May 2025 21:39:27 +0200
From: Sylvain Petinot <sylvain.petinot@...s.st.com>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>
CC: <benjamin.mugnier@...s.st.com>, <mchehab@...nel.org>, <robh@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
        <laurent.pinchart@...asonboard.com>, <linux-media@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <tomm.merciai@...il.com>
Subject: Re: [PATCH v6 2/2] media: i2c: Add driver for ST VD56G3 camera sensor

Hi Sakari,

Le 02/05/2025 à 00:20, Sakari Ailus a écrit :
> Hi Sylvain,
> 
> On Wed, Apr 30, 2025 at 04:19:14PM +0200, Sylvain Petinot wrote:
>>>> +static int vd56g3_subdev_init(struct vd56g3 *sensor)
>>>> +{
>>>> +	int ret;
>>>> +
>>>> +	/* Init remaining sub device ops */
>>>> +	sensor->sd.internal_ops = &vd56g3_internal_ops;
>>>> +	sensor->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
>>>> +	sensor->sd.entity.ops = &vd56g3_subdev_entity_ops;
>>>> +
>>>> +	/* Init source pad */
>>>> +	sensor->pad.flags = MEDIA_PAD_FL_SOURCE;
>>>> +	sensor->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
>>>> +	ret = media_entity_pads_init(&sensor->sd.entity, 1, &sensor->pad);
>>>> +	if (ret) {
>>>> +		dev_err(sensor->dev, "Failed to init media entity : %d", ret);
>>>> +		return ret;
>>>> +	}
>>>> +
>>>> +	/* Init controls */
>>>> +	ret = vd56g3_init_controls(sensor);
>>>> +	if (ret) {
>>>> +		dev_err(sensor->dev, "Controls initialization failed %d", ret);
>>>> +		goto err_media;
>>>> +	}
>>>> +
>>>> +	/* Init vd56g3 struct : default resolution + raw8 */
>>>> +	sensor->sd.state_lock = sensor->ctrl_handler.lock;
>>>> +	ret = v4l2_subdev_init_finalize(&sensor->sd);
>>>> +	if (ret) {
>>>> +		dev_err(sensor->dev, "subdev init error: %d", ret);
>>>> +		goto err_ctrls;
>>>> +	}
>>>> +
>>>> +	return vd56g3_update_controls(sensor);
>>>
>>> You're not holding the control handler's lock in the above call.
>>
>> If your comment is related to the fact that 'vd56g3_update_controls() can
>> fail and that we do not free control handler not cleanup media entity, it's
>> fixed in V7.
> 
> It's not. The access to the control handler is serialised by a mutex and
> you're not holding that mutex whilst calling vd56g3_update_controls() here.
> The same issue exists in accessing sub-device state.
> 

I'm sorry, I missed that ...
That should be better with something like :

	state = v4l2_subdev_lock_and_get_active_state(&sensor->sd);
	ret = vd56g3_update_controls(sensor);
	v4l2_subdev_unlock_state(state);

I'll prepare and push a V8.

> ...
> 
>>>> +	ret = vd56g3_parse_dt(sensor);
>>>> +	if (ret)
>>>> +		return dev_err_probe(dev, ret, "Failed to parse Device Tree.");
>>>
>>> No need for the trailing dot in these messages. Same elsewhere.
>>
>> You're right, Fixed in V7.
>> I took the opportunity to harmonize the error messages (Capital letter, no
>> space before ':', no trailing dot, missing '\n').
> 
> Ack, sounds good!
> 

-- 
Sylvain