Re: [PATCH v2] media: rcar-isp: ispcore: Fix inconsistent step sizes

["Barnabás Pőcze" <barnabas.pocze@ideasonboard.com>]

2026. 10. 04. 11:14 keltezéssel, Jacopo Mondi írta:
> Hi Barnabás
> 
> On Thu, Oct 01, 2026 at 10:51:30AM +0200, Barnabás Pőcze wrote:
>> `risp_io_{input,capture}_enum_framesizes()` sets the horizontal and vertical
>> step size to 2. However, `risp_io_{input,capture}_try_format()` passes 2
>> to `v4l_bound_align_image()`, which corresponds to a step size of 2^2 = 4.
>>
>> So move these constants into macros to avoid the repetition, and with that,
>> use 4 as the step size everywhere.
> 
> Why 4 ?
> 
> I can't find any such limit in documentation.
> 
> For input I don't find alignment constraints nor in CS or VSPX
> documentation.
> 
> For output I only see a requirement that the stride is 256 bits
> aligned, something that is enforced by risp_io_capture_try_format()
> already.
> 
> I see Niklas has reviewed the patch, so he might have found somewhere
> in the long documentation where the alignment for both input and
> capture nodes is described.

My primary goal was to remove the inconsistency between the reported and applied
step sizes. So I went with 4 because that was the applied step size, so with that,
it's quite certain that nothing that has worked will break.

Admittedly I do not know if that is the correct number, but I think that can
be considered a separate issue.



> 
>>
>> Fixes: 2151350f60d1 ("media: rcar-isp: Add support for ISPCORE")
>> Signed-off-by: Barnabás Pőcze <barnabas.pocze+renesas@ideasonboard.com>
>> Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
>> ---
>> changes in v2:
>>    * fix typo
>>
>> v1: https://lore.kernel.org/linux-media/20260929133020.342677-2-barnabas.pocze+renesas@ideasonboard.com
>> ---
>>   .../media/platform/renesas/rcar-isp/core-io.c | 40 +++++++++++--------
>>   1 file changed, 24 insertions(+), 16 deletions(-)
>>
>> diff --git a/drivers/media/platform/renesas/rcar-isp/core-io.c b/drivers/media/platform/renesas/rcar-isp/core-io.c
>> index 820af506f896c..b60b91f43d42d 100644
>> --- a/drivers/media/platform/renesas/rcar-isp/core-io.c
>> +++ b/drivers/media/platform/renesas/rcar-isp/core-io.c
>> @@ -15,6 +15,12 @@
>>
>>   #include "risp-core.h"
>>
>> +#define RISP_MIN_WIDTH 128
>> +#define RISP_MAX_WIDTH 5120
>> +#define RISP_MIN_HEIGHT 128
>> +#define RISP_MAX_HEIGHT 4096
>> +#define RISP_SIZE_ALIGNMENT 2 /* 2^2 = 4 */
> 
> The fact that 2 means 2^2 is only because of how
> v4l_bound_align_image() is implemented
> 
>> +
>>   #define risp_io_err(d, fmt, arg...)         dev_err((d)->core->dev, fmt, ##arg)
>>
>>   static struct risp_buffer *risp_io_vb2buf(struct vb2_v4l2_buffer *vb)
>> @@ -330,8 +336,9 @@ static void risp_io_input_try_format(struct rcar_isp_core_io *io,
>>   {
>>   	unsigned int bpp = 0;
>>
>> -	v4l_bound_align_image(&pix->width, 128, 5120, 2,
>> -			      &pix->height, 128, 4096, 2, 0);
>> +	v4l_bound_align_image(&pix->width, RISP_MIN_WIDTH, RISP_MAX_WIDTH, RISP_SIZE_ALIGNMENT,
>> +			      &pix->height, RISP_MIN_HEIGHT, RISP_MAX_HEIGHT, RISP_SIZE_ALIGNMENT,
> 
> Should we maybe use 1 here, unless it is documented that 4 is a
> requirement ?
> 
> My suspicion is that we originally meant '2' everywhere, but
> v4l_bound_align_image() is weird and if you pass '2' in it means
> '2^2' and this went unnoticed.
> 
>> +			      0);
>>
>>   	for (unsigned int i = 0; i < ARRAY_SIZE(risp_io_input_formats); i++) {
>>   		if (risp_io_input_formats[i].fourcc == pix->pixelformat) {
>> @@ -423,13 +430,13 @@ static int risp_io_input_enum_framesizes(struct file *file, void *fh,
>>
>>   	fsize->type = V4L2_FRMSIZE_TYPE_STEPWISE;
>>
>> -	fsize->stepwise.min_width = 128;
>> -	fsize->stepwise.max_width = 5120;
>> -	fsize->stepwise.step_width = 2;
>> +	fsize->stepwise.min_width = RISP_MIN_WIDTH;
>> +	fsize->stepwise.max_width = RISP_MAX_WIDTH;
>> +	fsize->stepwise.step_width = 1u << RISP_SIZE_ALIGNMENT;
>>
>> -	fsize->stepwise.min_height = 128;
>> -	fsize->stepwise.max_height = 4096;
>> -	fsize->stepwise.step_height = 2;
>> +	fsize->stepwise.min_height = RISP_MIN_HEIGHT;
>> +	fsize->stepwise.max_height = RISP_MAX_HEIGHT;
>> +	fsize->stepwise.step_height = 1u << RISP_SIZE_ALIGNMENT;
>>
>>   	return 0;
>>   }
>> @@ -720,8 +727,9 @@ static const struct v4l2_pix_format_mplane risp_io_capture_default_format = {
>>   static void risp_io_capture_try_format(struct rcar_isp_core_io *io,
>>   				       struct v4l2_pix_format_mplane *pix)
>>   {
>> -	v4l_bound_align_image(&pix->width, 128, 5120, 2,
>> -			      &pix->height, 128, 4096, 2, 0);
>> +	v4l_bound_align_image(&pix->width, RISP_MIN_WIDTH, RISP_MAX_WIDTH, RISP_SIZE_ALIGNMENT,
>> +			      &pix->height, RISP_MIN_HEIGHT, RISP_MAX_HEIGHT, RISP_SIZE_ALIGNMENT,
>> +			      0);
>>
>>   	pix->field = V4L2_FIELD_NONE;
>>   	pix->colorspace = V4L2_COLORSPACE_SRGB;
>> @@ -824,13 +832,13 @@ static int risp_io_capture_enum_framesizes(struct file *file, void *fh,
>>
>>   	fsize->type = V4L2_FRMSIZE_TYPE_STEPWISE;
>>
>> -	fsize->stepwise.min_width = 128;
>> -	fsize->stepwise.max_width = 5120;
>> -	fsize->stepwise.step_width = 2;
>> +	fsize->stepwise.min_width = RISP_MIN_WIDTH;
>> +	fsize->stepwise.max_width = RISP_MAX_WIDTH;
>> +	fsize->stepwise.step_width = 1u << RISP_SIZE_ALIGNMENT;
>>
>> -	fsize->stepwise.min_height = 128;
>> -	fsize->stepwise.max_height = 4096;
>> -	fsize->stepwise.step_height = 2;
>> +	fsize->stepwise.min_height = RISP_MIN_HEIGHT;
>> +	fsize->stepwise.max_height = RISP_MAX_HEIGHT;
>> +	fsize->stepwise.step_height = 1u << RISP_SIZE_ALIGNMENT;
>>
>>   	return 0;
>>   }
>> --
>> 2.55.0
>>
>>