[RFC v1 01/11] media: uapi: v4l2-isp: Add v4l2 ISP extensible statistics definitions

[Antoine Bouyer]

Hi Jacopo

On 4/3/26 10:19 AM, Jacopo Mondi wrote:
> 
> 
> Hello Antoine
> 
>     in cc Jai and Paul
> 
> Jai and Paul are working on upstreaming new ISP formats which would
> benefit from usage of extensible stats.
> 
> No pressure of course, just wanted to check how things are progressing
> on your side. Do you have an updated version of this patch which can
> be taken in ? Should we sync and work on an updated version ?

I'm still on it. Things are progressing well, but little bit delayed 
because of neoisp rework. I hope to submit patchset (v4l2-isp + neo) by 
end of this week.

BR
Antoine

> 
> Thanks!
>     j
> 
> On Fri, Jan 23, 2026 at 09:09:28AM +0100, Antoine Bouyer wrote:
>> Extend the v4l2-isp extensible format introduced for isp parameters buffer
>> to the statistics buffer as well.
>>
>> Like for ISP configuration purpose, that will help supporting various ISP
>> hardware versions reporting different statistics data with less impact on
>> userspace.
>>
>> The `v4l2_isp_stats_buffer` reuses the `v4l2_isp_params_buffer` container
>> definitions, with similar header, versions and flags. V0 and V1 versions
>> are provided to match with params versions. On the other side, ENABLE and
>> DISABLE flags are not really meaningfull for statistics purpose. So VALID
>> and INVALID flags are introduced. Purpose is to force ISP driver to
>> validate a statistics buffer, before it is consumed by userspace.
>>
>> Signed-off-by: Antoine Bouyer <antoine.bouyer at nxp.com>
>> ---
>>   include/uapi/linux/media/v4l2-isp.h | 85 +++++++++++++++++++++++++++++
>>   1 file changed, 85 insertions(+)
>>
>> diff --git a/include/uapi/linux/media/v4l2-isp.h b/include/uapi/linux/media/v4l2-isp.h
>> index 779168f9058e..ed1279b86694 100644
>> --- a/include/uapi/linux/media/v4l2-isp.h
>> +++ b/include/uapi/linux/media/v4l2-isp.h
>> @@ -99,4 +99,89 @@ struct v4l2_isp_params_buffer {
>>        __u8 data[] __counted_by(data_size);
>>   };
>>
>> +/**
>> + * enum v4l2_isp_stats_version - V4L2 ISP statistics versioning
>> + *
>> + * @V4L2_ISP_STATS_VERSION_V0: First version of the V4L2 ISP statistics format
>> + *                          (for compatibility)
>> + * @V4L2_ISP_STATS_VERSION_V1: First version of the V4L2 ISP statistics format
>> + *
>> + * V0 and V1 are identical, and comply with V4l2 ISP parameters versions. So
>> + * both V0 and V1 refers to the first version of the V4L2 ISP statistics
>> + * format.
>> + *
>> + * Future revisions of the V4L2 ISP statistics format should start from the
>> + * value of 2.
>> + */
>> +enum v4l2_isp_stats_version {
>> +     V4L2_ISP_STATS_VERSION_V0 = 0,
>> +     V4L2_ISP_STATS_VERSION_V1,
>> +};
>> +
>> +#define V4L2_ISP_PARAMS_FL_BLOCK_VALID               (1U << 0)
>> +#define V4L2_ISP_PARAMS_FL_BLOCK_INVALID     (1U << 1)
>> +
>> +/*
>> + * Reserve the first 8 bits for V4L2_ISP_STATS_FL_* flag.
>> + *
>> + * Driver-specific flags should be defined as:
>> + * #define DRIVER_SPECIFIC_FLAG0     ((1U << V4L2_ISP_STATS_FL_DRIVER_FLAGS(0))
>> + * #define DRIVER_SPECIFIC_FLAG1     ((1U << V4L2_ISP_STATS_FL_DRIVER_FLAGS(1))
>> + */
>> +#define V4L2_ISP_STATS_FL_DRIVER_FLAGS(n)       ((n) + 8)
>> +
>> +/**
>> + * struct v4l2_isp_stats_block_header - V4L2 extensible statistics block header
>> + * @type: The statistics block type (driver-specific)
>> + * @flags: A bitmask of block flags (driver-specific)
>> + * @size: Size (in bytes) of the statistics block, including this header
>> + *
>> + * This structure represents the common part of all the ISP statistics blocks.
>> + * Each statistics block shall embed an instance of this structure type as its
>> + * first member, followed by the block-specific statistics data.
>> + *
>> + * The @type field is an ISP driver-specific value that identifies the block
>> + * type. The @size field specifies the size of the parameters block.
>> + *
>> + * The @flags field is a bitmask of per-block flags V4L2_STATS_ISP_FL_* and
>> + * driver-specific flags specified by the driver header.
>> + */
>> +struct v4l2_isp_stats_block_header {
>> +     __u16 type;
>> +     __u16 flags;
>> +     __u32 size;
>> +} __attribute__((aligned(8)));
>> +
>> +/**
>> + * struct v4l2_isp_stats_buffer - V4L2 extensible statistics data
>> + * @version: The statistics buffer version (driver-specific)
>> + * @data_size: The statistics data effective size, excluding this header
>> + * @data: The statistics data
>> + *
>> + * This structure contains the statistics information of the ISP hardware,
>> + * serialized for userspace into a data buffer. Each statistics block is
>> + * represented by a block-specific structure which contains a
>> + * :c:type:`v4l2_isp_stats_block_header` entry as first member. Driver
>> + * populates the @data buffer with statistics information of the ISP blocks it
>> + * intends to share to userspace. As a consequence, the data buffer effective
>> + * size changes according to the number of ISP blocks that driver intends to
>> + * provide and is set by the driver in the @data_size field.
>> + *
>> + * The statistics buffer is versioned by the @version field to allow modifying
>> + * and extending its definition. Driver shall populate the @version field to
>> + * inform the userpsace about the version it intends to use. The userspace will
>> + * parse and handle the @data buffer according to the data layout specific to
>> + * the indicated version.
>> + *
>> + * For each ISP block that driver wants to report, a block-specific structure
>> + * is appended to the @data buffer, one after the other without gaps in
>> + * between. Driver shall populate the @data_size field with the effective
>> + * size, in bytes, of the @data buffer.
>> + */
>> +struct v4l2_isp_stats_buffer {
>> +     __u32 version;
>> +     __u32 data_size;
>> +     __u8 data[] __counted_by(data_size);
>> +};
>> +
>>   #endif /* _UAPI_V4L2_ISP_H_ */
>> --
>> 2.52.0
>>