linux-kernel - Re: [PATCH v3 10/15] media: rcar-csi2: Add .get_frame

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Message-ID: <3946a90a-0656-4f70-a773-1e205e55f37b@ideasonboard.com>
Date: Tue, 16 Dec 2025 15:18:23 +0200
From: Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>
To: Niklas Söderlund <niklas.soderlund@...natech.se>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
 Sakari Ailus <sakari.ailus@...ux.intel.com>, linux-media@...r.kernel.org,
 linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
 Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
 Laurent Pinchart <laurent.pinchart@...asonboard.com>,
 Jacopo Mondi <jacopo.mondi@...asonboard.com>
Subject: Re: [PATCH v3 10/15] media: rcar-csi2: Add .get_frame_desc op

Hi,

On 06/06/2025 15:14, Niklas Söderlund wrote:
> Hi Tomi,
> 
> Thanks for your work.
> 
> On 2025-05-30 16:50:39 +0300, Tomi Valkeinen wrote:
>> Add v4l2_subdev_pad_ops.get_frame_desc() implementation.
>>
>> We also implement a fallback for the case where the upstream subdevice
>> does not implement .get_frame_desc. It assumes a single stream with VC =
>> 0 and DT based on the configured stream mbus format.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>
>> ---
>>  drivers/media/platform/renesas/rcar-csi2.c | 56 ++++++++++++++++++++++++++++++
>>  1 file changed, 56 insertions(+)
>>
>> diff --git a/drivers/media/platform/renesas/rcar-csi2.c b/drivers/media/platform/renesas/rcar-csi2.c
>> index 20bd44274bd2..65c7f3040696 100644
>> --- a/drivers/media/platform/renesas/rcar-csi2.c
>> +++ b/drivers/media/platform/renesas/rcar-csi2.c
>> @@ -1676,12 +1676,68 @@ static int rcsi2_set_pad_format(struct v4l2_subdev *sd,
>>  	return 0;
>>  }
>>  
>> +static int rcsi2_get_frame_desc_fallback(struct v4l2_subdev *sd,
>> +					 unsigned int pad,
>> +					 struct v4l2_mbus_frame_desc *fd)
>> +{
>> +	const struct rcar_csi2_format *format;
>> +	struct v4l2_subdev_state *state;
>> +	struct v4l2_mbus_framefmt *fmt;
>> +	int ret = 0;
>> +
>> +	state = v4l2_subdev_lock_and_get_active_state(sd);
>> +
>> +	fmt = v4l2_subdev_state_get_format(state, RCAR_CSI2_SINK, 0);
>> +	if (!fmt) {
>> +		ret = -EINVAL;
>> +		goto out;
>> +	}
>> +
>> +	format = rcsi2_code_to_fmt(fmt->code);
>> +	if (!format) {
>> +		ret = -EINVAL;
>> +		goto out;
>> +	}
>> +
>> +	fd->num_entries = 1;
>> +	fd->type = V4L2_MBUS_FRAME_DESC_TYPE_CSI2;
>> +	fd->entry[0].stream = 0;
>> +	fd->entry[0].pixelcode = fmt->code;
>> +	fd->entry[0].bus.csi2.vc = 0;
>> +	fd->entry[0].bus.csi2.dt = format->datatype;
>> +
>> +out:
>> +	v4l2_subdev_unlock_state(state);
>> +
>> +	return ret;
>> +}
>> +
>> +static int rcsi2_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
>> +				struct v4l2_mbus_frame_desc *fd)
>> +{
>> +	struct rcar_csi2 *priv = sd_to_csi2(sd);
>> +	int ret;
>> +
>> +	if (WARN_ON(!priv->info->use_isp))
>> +		return -ENOTTY;
> 
> This looks odd, why can't we support the frame descriptor and streams on 
> Gen3 that do not use the ISP Channel Selector?

Yes, this is not right. There was another similar case. I think they are
remnants of a gen4-only series.

 Tomi

> 
>> +
>> +	if (WARN_ON(pad != RCAR_CSI2_SOURCE_VC0))
>> +		return -EINVAL;
>> +
>> +	ret = v4l2_subdev_get_frame_desc_passthrough(sd, pad, fd);
>> +	if (ret == -ENOIOCTLCMD)
>> +		ret = rcsi2_get_frame_desc_fallback(sd, pad, fd);
>> +	return ret;
>> +}
>> +
>>  static const struct v4l2_subdev_pad_ops rcar_csi2_pad_ops = {
>>  	.enable_streams = rcsi2_enable_streams,
>>  	.disable_streams = rcsi2_disable_streams,
>>  
>>  	.set_fmt = rcsi2_set_pad_format,
>>  	.get_fmt = v4l2_subdev_get_fmt,
>> +
>> +	.get_frame_desc = rcsi2_get_frame_desc,
>>  };
>>  
>>  static const struct v4l2_subdev_ops rcar_csi2_subdev_ops = {
>>
>> -- 
>> 2.43.0
>>
>