Re: [PATCH v9 11/19] media: ti: j721e-csi2rx: add support for processing virtual channels

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

On 14/01/26 21:01, Tomi Valkeinen wrote:
> Hi,


Hi Tomi,

Thank you for the review !

>
> On 30/12/2025 10:32, 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 VC 0.
>>
>> get_frame_desc() works for single stream case, but as we don't
> Is that supposed to say "get_frame_desc works for multi-stream use case"?


This line has been misleading from many previous versions of this 
series. The main point to highlight in this part of the commit message 
is that we are enabling multi stream support in the later patches of the 
series, so in this patch we will stick to using stream 0. I will remove 
the line talking about "get_frame_desc() works for single/multi stream 
use case".

>
>> 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.
>>
>> Reviewed-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
>> 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   | 45 ++++++++++++++++++-
>>   1 file changed, 44 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> index f54ad67ff3f9d..6f9f34aa26f1b 100644
>> --- a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> @@ -32,6 +32,7 @@
>>   #define SHIM_DMACNTX_YUV422		GENMASK(27, 26)
>>   #define SHIM_DMACNTX_DUAL_PCK_CFG	BIT(24)
>>   #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
>> @@ -110,6 +111,9 @@ struct ti_csi2rx_ctx {
>>   	struct media_pad		pad;
>>   	u32				sequence;
>>   	u32				idx;
>> +	u32				vc;
>> +	u32				dt;
>> +	u32				stream;
>>   };
>>   
>>   struct ti_csi2rx_dev {
>> @@ -570,7 +574,7 @@ static void ti_csi2rx_setup_shim(struct ti_csi2rx_ctx *ctx)
>>   	ti_csi2rx_request_max_ppc(csi);
>>   
>>   	reg = SHIM_DMACNTX_EN;
>> -	reg |= FIELD_PREP(SHIM_DMACNTX_FMT, fmt->csi_dt);
>> +	reg |= FIELD_PREP(SHIM_DMACNTX_FMT, ctx->dt);
>>   
>>   	/*
>>   	 * The hardware assumes incoming YUV422 8-bit data on MIPI CSI2 bus
>> @@ -610,6 +614,7 @@ 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));
>>   
>> @@ -884,12 +889,41 @@ static void ti_csi2rx_buffer_queue(struct vb2_buffer *vb)
>>   	}
>>   }
>>   
>> +static int ti_csi2rx_get_vc_and_dt(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;
>> +
>> +	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) {
>> +			ctx->vc = fd.entry[i].bus.csi2.vc;
>> +			ctx->dt = fd.entry[i].bus.csi2.dt;
>> +		}
>> +	}
> I think you can "break" when you find the stream. But this should also
> catch the case when there's no matching stream, and give an error in
> that case.


Right. Will add.


Rishikesh

>
>   Tomi
>
>> +
>> +	return 0;
>> +}
>> +
>>   static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
>>   {
>>   	struct ti_csi2rx_ctx *ctx = vb2_get_drv_priv(vq);
>>   	struct ti_csi2rx_dev *csi = ctx->csi;
>>   	struct ti_csi2rx_dma *dma = &ctx->dma;
>>   	struct ti_csi2rx_buffer *buf;
>> +	const struct ti_csi2rx_fmt *fmt;
>>   	unsigned long flags;
>>   	int ret = 0;
>>   
>> @@ -904,6 +938,15 @@ static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
>>   	if (ret)
>>   		goto err;
>>   
>> +	ret = ti_csi2rx_get_vc_and_dt(ctx);
>> +	if (ret == -ENOIOCTLCMD) {
>> +		ctx->vc = 0;
>> +		fmt = find_format_by_fourcc(ctx->v_fmt.fmt.pix.pixelformat);
>> +		ctx->dt = fmt->csi_dt;
>> +	} else if (ret < 0) {
>> +		goto err;
>> +	}
>> +
>>   	ti_csi2rx_setup_shim(ctx);
>>   
>>   	ctx->sequence = 0;