Re: [PATCH v7 01/16] media: ti: j721e-csi2rx: Remove word size alignment on frame width

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

On 22-09-2025 17:26, Tomi Valkeinen wrote:
> Hi,


Hi Tomi,


>
> On 11/09/2025 13:28, Rishikesh Donadkar wrote:
>> j721e-csi2rx driver has a limitation of frame width being a multiple
>> word size. However, there is no such limitation imposed by the
>> hardware [1].
>>
>> Remove this limitation from the driver.
>>
>> Link: https://www.ti.com/lit/pdf/spruj16
>> Reviewed-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
>> Signed-off-by: Rishikesh Donadkar <r-donadkar@ti.com>
>> ---
>>   .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 23 ++++---------------
>>   1 file changed, 4 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> index 3992f8b754b7..6a981b5f5d51 100644
>> --- a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> @@ -250,19 +250,12 @@ static void ti_csi2rx_fill_fmt(const struct ti_csi2rx_fmt *csi_fmt,
>>   			       struct v4l2_format *v4l2_fmt)
>>   {
>>   	struct v4l2_pix_format *pix = &v4l2_fmt->fmt.pix;
>> -	unsigned int pixels_in_word;
>> -
>> -	pixels_in_word = PSIL_WORD_SIZE_BYTES * 8 / csi_fmt->bpp;
> The define for PSIL_WORD_SIZE_BYTES can also be removed, if I'm not
> mistaken.


Yes, Thanks for pointing out !


>
> I assume this has been tested, but I'm still a bit curious. Usually
> these kind of lines of code don't just appear out of nowhere. You linked
> to AM62Ax docs. None of the other SoCs have any limitations here either?


This has been tested with IMX219 : 1640x1232 -f SRGGB8. Looking at the 
docs, I don't see such limitation mentioned anywhere for the other SoC 
as well.


Regards,

Rishikesh

>
> PSIL_WORD_SIZE_BYTES hints to a system DMA level limit, not CSI-2 RX
> limit, so I wonder if some earlier SoCs had such limitations in the DMA?
>
>   Tomi
>
>>   
>>   	/* Clamp width and height to sensible maximums (16K x 16K) */
>>   	pix->width = clamp_t(unsigned int, pix->width,
>> -			     pixels_in_word,
>> -			     MAX_WIDTH_BYTES * 8 / csi_fmt->bpp);
>> +			     1, MAX_WIDTH_BYTES * 8 / csi_fmt->bpp);
>>   	pix->height = clamp_t(unsigned int, pix->height, 1, MAX_HEIGHT_LINES);
>>   
>> -	/* Width should be a multiple of transfer word-size */
>> -	pix->width = rounddown(pix->width, pixels_in_word);
>> -
>>   	v4l2_fmt->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
>>   	pix->pixelformat = csi_fmt->fourcc;
>>   	pix->bytesperline = pix->width * (csi_fmt->bpp / 8);
>> @@ -360,23 +353,15 @@ static int ti_csi2rx_enum_framesizes(struct file *file, void *fh,
>>   				     struct v4l2_frmsizeenum *fsize)
>>   {
>>   	const struct ti_csi2rx_fmt *fmt;
>> -	unsigned int pixels_in_word;
>>   
>>   	fmt = find_format_by_fourcc(fsize->pixel_format);
>>   	if (!fmt || fsize->index != 0)
>>   		return -EINVAL;
>>   
>> -	/*
>> -	 * Number of pixels in one PSI-L word. The transfer happens in multiples
>> -	 * of PSI-L word sizes.
>> -	 */
>> -	pixels_in_word = PSIL_WORD_SIZE_BYTES * 8 / fmt->bpp;
>> -
>>   	fsize->type = V4L2_FRMSIZE_TYPE_STEPWISE;
>> -	fsize->stepwise.min_width = pixels_in_word;
>> -	fsize->stepwise.max_width = rounddown(MAX_WIDTH_BYTES * 8 / fmt->bpp,
>> -					      pixels_in_word);
>> -	fsize->stepwise.step_width = pixels_in_word;
>> +	fsize->stepwise.min_width = 1;
>> +	fsize->stepwise.max_width = MAX_WIDTH_BYTES * 8 / fmt->bpp;
>> +	fsize->stepwise.step_width = 1;
>>   	fsize->stepwise.min_height = 1;
>>   	fsize->stepwise.max_height = MAX_HEIGHT_LINES;
>>   	fsize->stepwise.step_height = 1;