Re: [RFC PATCH] media: staging: ipu3-imgu: add the AWB memory layout

[Bingbu Cao <bingbu.cao@linux.intel.com>]

Jean-Michel,

Thanks for your patch.

On 9/8/21 4:17 PM, Laurent Pinchart wrote:
> Hello,
> 
> (CC'ing Tomasz)
> 
> Gentle ping.
> 
> On Wed, Sep 01, 2021 at 12:34:00AM +0300, Laurent Pinchart wrote:
>> On Tue, Aug 31, 2021 at 08:51:40PM +0200, Jean-Michel Hautbois wrote:
>>> While parsing the RAW AWB metadata, the AWB layout was missing to fully
>>> understand which byte corresponds to which feature. Make the field names
>>> and usage explicit, as it is used by the userspace applications.
>>>
>>> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
>>> ---
>>> This structure layout is defined in CrOs:
>>> https://chromium.googlesource.com/chromiumos/platform/arc-camera/+/refs/heads/master/hal/intel/include/ia_imaging/awb_public.h
>>>
>>> There are a few things not really understood right now:
>>> - Is sat_ratio a full scale ratio (I can't get more than some values out
>>>   of it, is it a ratio of 25%, 50%, 75%, 100% ?)
>>> - What are the real minimum and maximum values for the grid size ? From
>>>   CrOs it appears to be [16, 80] for width and [16, 60] for height while
>>>   in this file it seems to be [16, 160] for width and not really defined
>>>   for height AFAICT ?
>>> - Same for the block_width_log2 and block_height_log2 which are [3, 7]
>>>   in this file and [3, 6] in the awb_public.h header ?
>>>
>>>  .../media/ipu3/include/uapi/intel-ipu3.h      | 38 ++++++++++++++-----
>>>  1 file changed, 29 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h b/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h
>>> index fa3d6ee5adf2..83191aff2ddd 100644
>>> --- a/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h
>>> +++ b/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h
>>> @@ -61,20 +61,40 @@ struct ipu3_uapi_grid_config {
>>>  	__u16 y_end;
>>>  } __packed;
>>>  
>>> +/**
>>> + * struct ipu3_uapi_awb_raw_buffer - Memory layout for each cell in AWB
>>> + *
>>> + * @Gr_avg:	Green average for red lines in the cell.
>>> + * @R_avg:	Red average in the cell.
>>> + * @B_avg:	Blue average in the cell.
>>> + * @Gb_avg:	Green average for blue lines in the cell.
>>> + * @sat_ratio:  Saturation ratio in the cell.
>>> + * @padding0:   Unused byte for padding.
>>> + * @padding1:   Unused byte for padding.
>>> + * @padding2:   Unused byte for padding.
>>> + */
>>> +struct ipu3_uapi_awb_raw_buffer {
>>> +    unsigned char Gr_avg;
>>> +    unsigned char R_avg;
>>> +    unsigned char B_avg;
>>> +    unsigned char Gb_avg;
>>> +    unsigned char sat_ratio;
>>> +    unsigned char padding0;
>>> +    unsigned char padding1;
>>> +    unsigned char padding2;

It is fine for me to define and exposure the awb memory layout in uAPI.

nit: use __u8 here?

>>> +} __packed;
>>> +
>>>  /*
>>>   * The grid based data is divided into "slices" called set, each slice of setX
>>>   * refers to ipu3_uapi_grid_config width * height_per_slice.
>>>   */
>>>  #define IPU3_UAPI_AWB_MAX_SETS				60
>>> -/* Based on grid size 80 * 60 and cell size 16 x 16 */
>>> -#define IPU3_UAPI_AWB_SET_SIZE				1280
>>> -#define IPU3_UAPI_AWB_MD_ITEM_SIZE			8
>>> -#define IPU3_UAPI_AWB_SPARE_FOR_BUBBLES \
>>> -	(IPU3_UAPI_MAX_BUBBLE_SIZE * IPU3_UAPI_MAX_STRIPES * \
>>> -	 IPU3_UAPI_AWB_MD_ITEM_SIZE)
>>> +#define AWB_PUBLIC_NUM_OF_ITEMS_IN_SET			160
>>> +/* Based on max grid height + Spare for bubbles */
>>> +#define AWB_PUBLIC_NUM_OF_SETS_IN_BUFFER IPU3_UAPI_AWB_MAX_SETS + \
>>> +	(IPU3_UAPI_MAX_BUBBLE_SIZE * IPU3_UAPI_MAX_STRIPES)
>>>  #define IPU3_UAPI_AWB_MAX_BUFFER_SIZE \
>>> -	(IPU3_UAPI_AWB_MAX_SETS * \
>>> -	 (IPU3_UAPI_AWB_SET_SIZE + IPU3_UAPI_AWB_SPARE_FOR_BUBBLES))
>>> +        AWB_PUBLIC_NUM_OF_SETS_IN_BUFFER * AWB_PUBLIC_NUM_OF_ITEMS_IN_SET

It's better to update the name of 'IPU3_UAPI_AWB_MAX_BUFFER_SIZE' to align current
definition.

>>>  
>>>  /**
>>>   * struct ipu3_uapi_awb_raw_buffer - AWB raw buffer
>>> @@ -83,7 +103,7 @@ struct ipu3_uapi_grid_config {
>>>   *		the average values for each color channel.
>>>   */
>>>  struct ipu3_uapi_awb_raw_buffer {
>>> -	__u8 meta_data[IPU3_UAPI_AWB_MAX_BUFFER_SIZE]
>>> +	struct ipu3_uapi_awb_raw_buffer meta_data[IPU3_UAPI_AWB_MAX_BUFFER_SIZE]
>>>  		__attribute__((aligned(32)));
>>>  } __packed;
>>>  
> 

-- 
Best regards,
Bingbu Cao