Re: [PATCH v3 08/13] media: ti: j721e-csi2rx: add support for processing virtual channels

[Rishikesh Donadkar <r-donadkar@ti.com>]

On 21/04/25 19:04, Laurent Pinchart wrote:
> Hi Rishikesh,
>
> Thank you for the patch.


Hi Laurent,

Thanks you for the review.


>
> On Thu, Apr 17, 2025 at 12:25:49PM +0530, Rishikesh Donadkar wrote:
>> From: Jai Luthra <j-luthra@ti.com>
>>
>> Use get_frame_desc() to get the frame desc from the connected source,
>> and use the provided virtual channel instead of hardcoded one.
>>
>> get_frame_desc() works per stream, but as we don't support multiple
>> streams yet, we will just always use stream 0. If the source doesn't
>> support get_frame_desc(), fall back to the previous method of always
>> capturing virtual channel 0.
>>
>> Co-developed-by: Pratyush Yadav <p.yadav@ti.com>
>> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
>> Signed-off-by: Jai Luthra <j-luthra@ti.com>
>> Signed-off-by: Rishikesh Donadkar <r-donadkar@ti.com>
>> ---
>>   .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 39 +++++++++++++++++++
>>   1 file changed, 39 insertions(+)
>>
>> diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> index e85d04d7c2ff9..3e2a0517a9096 100644
>> --- a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> @@ -29,6 +29,7 @@
>>   #define SHIM_DMACNTX_EN			BIT(31)
>>   #define SHIM_DMACNTX_YUV422		GENMASK(27, 26)
>>   #define SHIM_DMACNTX_SIZE		GENMASK(21, 20)
>> +#define SHIM_DMACNTX_VC			GENMASK(9, 6)
>>   #define SHIM_DMACNTX_FMT		GENMASK(5, 0)
>>   #define SHIM_DMACNTX_YUV422_MODE_11	3
>>   #define SHIM_DMACNTX_SIZE_8		0
>> @@ -105,6 +106,8 @@ struct ti_csi2rx_ctx {
>>   	struct media_pad		pad;
>>   	u32				sequence;
>>   	u32				idx;
>> +	u32				vc;
>> +	u32				stream;
>>   };
>>   
>>   struct ti_csi2rx_dev {
>> @@ -573,6 +576,7 @@ static void ti_csi2rx_setup_shim(struct ti_csi2rx_ctx *ctx)
>>   	}
>>   
>>   	reg |= FIELD_PREP(SHIM_DMACNTX_SIZE, fmt->size);
>> +	reg |= FIELD_PREP(SHIM_DMACNTX_VC, ctx->vc);
>>   
>>   	writel(reg, csi->shim + SHIM_DMACNTX(ctx->idx));
>>   
>> @@ -846,6 +850,33 @@ static void ti_csi2rx_buffer_queue(struct vb2_buffer *vb)
>>   	}
>>   }
>>   
>> +static int ti_csi2rx_get_vc(struct ti_csi2rx_ctx *ctx)
>> +{
>> +	struct ti_csi2rx_dev *csi = ctx->csi;
>> +	struct v4l2_mbus_frame_desc fd;
>> +	struct media_pad *pad;
>> +	int ret, i;
> i can never be negative, you can make it an unsigned int.


Will fix.


>
>> +
>> +	pad = media_entity_remote_pad_unique(&csi->subdev.entity, MEDIA_PAD_FL_SOURCE);
>> +	if (!pad)
>> +		return -ENODEV;
>> +
>> +	ret = v4l2_subdev_call(csi->source, pad, get_frame_desc, pad->index,
>> +			       &fd);
>> +	if (ret)
>> +		return ret;
>> +
>> +	if (fd.type != V4L2_MBUS_FRAME_DESC_TYPE_CSI2)
>> +		return -EINVAL;
>> +
>> +	for (i = 0; i < fd.num_entries; i++) {
>> +		if (ctx->stream == fd.entry[i].stream)
>> +			return fd.entry[i].bus.csi2.vc;
>> +	}
>> +
>> +	return -ENODEV;
>> +}
>> +
>>   static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
>>   {
>>   	struct ti_csi2rx_ctx *ctx = vb2_get_drv_priv(vq);
>> @@ -866,6 +897,14 @@ static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
>>   	if (ret)
>>   		goto err;
>>   
>> +	ret = ti_csi2rx_get_vc(ctx);
>> +	if (ret == -ENOIOCTLCMD)
>> +		ctx->vc = 0;
>> +	else if (ret < 0)
>> +		goto err;
>> +	else
>> +		ctx->vc = ret;
>> +
> When you'll add support for multiple streams in patch 11/13, you will
> end up calling .get_frame_desc() once per stream. All calls will return
> the same information, so it's a bit wasteful. Would it be possible to
> call this function once only at start time, and cache and use the
> results for all video devices ?


Yes, Right. I will make these changes in 11/13 when adding

muti-stream support.


>
>>   	ti_csi2rx_setup_shim(ctx);
>>   
>>   	ctx->sequence = 0;
Regards,
Rishikesh