Re: [PATCH] media: vimc: Apply right blue and red channels to BGR

[Helen Koike <helen.koike@collabora.com>]

Hi Kaaira,

Thanks for the patch.

On 5/22/20 4:11 AM, Kaaira Gupta wrote:
> rgb[] is already calculated in the right order, there is no need to swap
> the blue and red channels in it for BGR images. Hence give right rgb
> channels to the src_frame.

It would be nice if you explain the issue you are facing, and what this fixes.

> 
> Signed-off-by: Kaaira Gupta <kgupta@es.iitr.ac.in>
> ---
>  drivers/media/test-drivers/vimc/vimc-debayer.c | 14 ++------------
>  1 file changed, 2 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/media/test-drivers/vimc/vimc-debayer.c b/drivers/media/test-drivers/vimc/vimc-debayer.c
> index c3f6fef34f68..d41d9f6180df 100644
> --- a/drivers/media/test-drivers/vimc/vimc-debayer.c
> +++ b/drivers/media/test-drivers/vimc/vimc-debayer.c
> @@ -318,21 +318,11 @@ static void vimc_deb_process_rgb_frame(struct vimc_deb_device *vdeb,
>  				       unsigned int col,
>  				       unsigned int rgb[3])
>  {
> -	const struct vimc_pix_map *vpix;
>  	unsigned int i, index;
>  
> -	vpix = vimc_pix_map_by_code(vdeb->src_code);
>  	index = VIMC_FRAME_INDEX(lin, col, vdeb->sink_fmt.width, 3);
> -	for (i = 0; i < 3; i++) {
> -		switch (vpix->pixelformat) {
> -		case V4L2_PIX_FMT_RGB24:
> -			vdeb->src_frame[index + i] = rgb[i];
> -			break;
> -		case V4L2_PIX_FMT_BGR24:
> -			vdeb->src_frame[index + i] = rgb[2 - i];
> -			break;
> -		}
> -	}

This code looks correct to me.

The rgb[] arrays is an intermediary representation of the pixel, in the order of Red Green Blue.

If you look at vimc_deb_calc_rgb_sink(), you will see that rgb[] is indexed by this enum:

enum vimc_deb_rgb_colors {
	VIMC_DEB_RED = 0,
	VIMC_DEB_GREEN = 1,
	VIMC_DEB_BLUE = 2,
};

So rgb[0] is the red component, rgb[1] green and rgb[2] blue.

The, in this part of the code that you removed, we use rgb[] array to calculate the final frame.

So, if there is an error, then I don't think it is here.
Maybe the rgb[] array is wrong, and the error would be somewhere in vimc_deb_calc_rgb_sink().

Regards,
Helen


> +	for (i = 0; i < 3; i++)
> +		vdeb->src_frame[index + i] = rgb[i];
>  }
>  
>  static int vimc_deb_s_stream(struct v4l2_subdev *sd, int enable)
>