Re: [PATCH v4 3/3] media: nxp: imx8-isi: Add additional 32-bit RGB format support

[Frank Li <Frank.li@oss.nxp.com>]

On Fri, Jul 24, 2026 at 08:03:42AM +0000, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [High] V4L2_PIX_FMT_RGBX32 and V4L2_PIX_FMT_XBGR32 share the same isi_in_format, which will result in swapped color channels during M2M reads.
> --
>
> --- Patch [3]: [PATCH v4 3/3] media: nxp: imx8-isi: Add additional 32-bit RGB format support ---
> commit 60dac66057b0040d017034c0952f79ec30cec366
> Author: Guoniu Zhou <guoniu.zhou@oss.nxp.com>
>
> media: nxp: imx8-isi: Add additional 32-bit RGB format support
>
> This commit adds support for additional 32-bit RGB pixel formats (BGRA32,
> RGBA32, BGRX32, RGBX32, ARGB2101010) to the i.MX8 ISI driver. Formats with
> an alpha channel only support capture, as the ISI ignores alpha bits when
> reading from memory.
>
> > diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-video.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-video.c
> > --- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-video.c
> > +++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-video.c
> > @@ -166,6 +166,57 @@ static const struct mxc_isi_format_info mxc_isi_formats[] = {
>
> [ ... ]
>
> > +	}, {
> > +		.mbus_code	= MEDIA_BUS_FMT_RGB888_1X24,
> > +		.fourcc		= V4L2_PIX_FMT_RGBX32,
> > +		.type		= MXC_ISI_VIDEO_CAP | MXC_ISI_VIDEO_M2M_OUT
> > +				| MXC_ISI_VIDEO_M2M_CAP,
> > +		.isi_in_format	= CHNL_MEM_RD_CTRL_IMG_TYPE_XBGR8,
>
> [Severity: High]
> Does this mapping for V4L2_PIX_FMT_RGBX32 swap the red and blue channels
> during M2M reads?
>
> The newly added V4L2_PIX_FMT_RGBX32 format (memory layout R,G,B,X) maps to
> CHNL_MEM_RD_CTRL_IMG_TYPE_XBGR8 for DMA reads.
>
> However, earlier in mxc_isi_formats[], the pre-existing V4L2_PIX_FMT_XBGR32
> format (memory layout B,G,R,X) uses this exact same configuration:


Is this true?

Frank
>
> 	{
> 		.mbus_code	= MEDIA_BUS_FMT_RGB888_1X24,
> 		.fourcc		= V4L2_PIX_FMT_XBGR32,
> 		.type		= MXC_ISI_VIDEO_CAP | MXC_ISI_VIDEO_M2M_OUT
> 				| MXC_ISI_VIDEO_M2M_CAP,
> 		.isi_in_format	= CHNL_MEM_RD_CTRL_IMG_TYPE_XBGR8,
>         ...
> 	}
>
> Since these two formats have opposite red and blue channel locations in
> memory, can the hardware DMA controller correctly interpret both layouts
> using the identical input format configuration?
>
> It looks like this could result in corrupted color conversions for one of
> these formats during M2M operations.
>
> > +		.isi_out_format	= CHNL_IMG_CTRL_FORMAT_XBGR888,
> > +		.mem_planes	= 1,
> > +		.color_planes	= 1,
> > +		.depth		= { 32 },
> > +		.encoding	= MXC_ISI_ENC_RGB,
>
> [ ... ]
>
> --
> Sashiko AI review · https://sashiko.dev/#/patchset/20260724-isi-v4-0-27df7b5f6060@oss.nxp.com?part=3