[libcamera-devel] [RFC 1/1] libcamera: V4L2VideoDevice::to[V4L2]PixelFormat(): add Bayer formats

[Niklas Söderlund]

Hi Andrey,

Thanks for your work.

On 2020-04-05 00:57:30 +0300, Andrey Konovalov wrote:
> Add support for 8-bit, 10-bit, and 10-bit packed raw Bayer formats in
> toPixelFormat() and toV4L2PixelFormat() methods of V4L2VideoDevice class.
> 
> Signed-off-by: Andrey Konovalov <andrey.konovalov at linaro.org>
> ---
>  src/libcamera/v4l2_videodevice.cpp | 56 ++++++++++++++++++++++++++++++
>  1 file changed, 56 insertions(+)
> 
> diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
> index eb33a68..2e3aafc 100644
> --- a/src/libcamera/v4l2_videodevice.cpp
> +++ b/src/libcamera/v4l2_videodevice.cpp
> @@ -1687,6 +1687,36 @@ PixelFormat V4L2VideoDevice::toPixelFormat(V4L2PixelFormat v4l2Fourcc)
>  	case V4L2_PIX_FMT_MJPEG:
>  		return PixelFormat(DRM_FORMAT_MJPEG);
>  
> +	/* 8-bit Bayer formats. */
> +	case V4L2_PIX_FMT_SRGGB8:
> +		return PixelFormat(DRM_FORMAT_SRGGB8);
> +	case V4L2_PIX_FMT_SGRBG8:
> +		return PixelFormat(DRM_FORMAT_SGRBG8);
> +	case V4L2_PIX_FMT_SGBRG8:
> +		return PixelFormat(DRM_FORMAT_SGBRG8);
> +	case V4L2_PIX_FMT_SBGGR8:
> +		return PixelFormat(DRM_FORMAT_SBGGR8);
> +
> +	/* 10-bit Bayer formats. */
> +	case V4L2_PIX_FMT_SRGGB10:
> +		return PixelFormat(DRM_FORMAT_SRGGB10);
> +	case V4L2_PIX_FMT_SGRBG10:
> +		return PixelFormat(DRM_FORMAT_SGRBG10);
> +	case V4L2_PIX_FMT_SGBRG10:
> +		return PixelFormat(DRM_FORMAT_SGBRG10);
> +	case V4L2_PIX_FMT_SBGGR10:
> +		return PixelFormat(DRM_FORMAT_SBGGR10);
> +
> +	/* 10-bit Bayer packed formats. */
> +	case V4L2_PIX_FMT_SRGGB10P:
> +		return PixelFormat(DRM_FORMAT_SRGGB10, MIPI_FORMAT_MOD_CSI2_PACKED);
> +	case V4L2_PIX_FMT_SGRBG10P:
> +		return PixelFormat(DRM_FORMAT_SGRBG10, MIPI_FORMAT_MOD_CSI2_PACKED);
> +	case V4L2_PIX_FMT_SGBRG10P:
> +		return PixelFormat(DRM_FORMAT_SGBRG10, MIPI_FORMAT_MOD_CSI2_PACKED);
> +	case V4L2_PIX_FMT_SBGGR10P:
> +		return PixelFormat(DRM_FORMAT_SBGGR10, MIPI_FORMAT_MOD_CSI2_PACKED);

This fits the idea we had when adding the MIPI_FORMAT_MOD_CSI2_PACKED 
modifier. But it's I misunderstood how modifies are used in DRM when 
doing so. The patch for DRM is not accepted in upstream Linux yet and 
this is a local change we took into libcamera where we bet on it was the 
right approach.

Now we know we need to think one more time about if this is right 
solution for this problem so I'm  bit reluctant building more things on 
top of. If other thinks it's fine to do so I will not block it however.

> +
>  	/* V4L2 formats not yet supported by DRM. */
>  	case V4L2_PIX_FMT_GREY:
>  	default:
> @@ -1734,6 +1764,8 @@ V4L2PixelFormat V4L2VideoDevice::toV4L2PixelFormat(const PixelFormat &pixelForma
>  V4L2PixelFormat V4L2VideoDevice::toV4L2PixelFormat(const PixelFormat &pixelFormat,
>  						   bool multiplanar)
>  {
> +	bool csi2Packed = pixelFormat.modifier() == MIPI_FORMAT_MOD_CSI2_PACKED;
> +
>  	switch (pixelFormat) {
>  	/* RGB formats. */
>  	case DRM_FORMAT_BGR888:
> @@ -1777,6 +1809,30 @@ V4L2PixelFormat V4L2VideoDevice::toV4L2PixelFormat(const PixelFormat &pixelForma
>  	/* Compressed formats. */
>  	case DRM_FORMAT_MJPEG:
>  		return V4L2PixelFormat(V4L2_PIX_FMT_MJPEG);
> +
> +	/* 8-bit Bayer formats. */
> +	case DRM_FORMAT_SRGGB8:
> +		return V4L2PixelFormat(V4L2_PIX_FMT_SRGGB8);
> +	case DRM_FORMAT_SGRBG8:
> +		return V4L2PixelFormat(V4L2_PIX_FMT_SGRBG8);
> +	case DRM_FORMAT_SGBRG8:
> +		return V4L2PixelFormat(V4L2_PIX_FMT_SGBRG8);
> +	case DRM_FORMAT_SBGGR8:
> +		return V4L2PixelFormat(V4L2_PIX_FMT_SBGGR8);
> +
> +	/* 10-bit Bayer formats, the packed ones included. */
> +	case DRM_FORMAT_SRGGB10:
> +		return (csi2Packed) ? V4L2PixelFormat(V4L2_PIX_FMT_SRGGB10P)
> +			: V4L2PixelFormat(V4L2_PIX_FMT_SRGGB10);
> +	case DRM_FORMAT_SGRBG10:
> +		return (csi2Packed) ? V4L2PixelFormat(V4L2_PIX_FMT_SGRBG10P)
> +			: V4L2PixelFormat(V4L2_PIX_FMT_SGRBG10);
> +	case DRM_FORMAT_SGBRG10:
> +		return (csi2Packed) ? V4L2PixelFormat(V4L2_PIX_FMT_SGBRG10P)
> +			: V4L2PixelFormat(V4L2_PIX_FMT_SGBRG10);
> +	case DRM_FORMAT_SBGGR10:
> +		return (csi2Packed) ? V4L2PixelFormat(V4L2_PIX_FMT_SBGGR10P)
> +			: V4L2PixelFormat(V4L2_PIX_FMT_SBGGR10);

If the issue above is resolved in such a way that this patch is accepted 
this needs to be extended to also support IPU3_FORMAT_MOD_PACKED.

>  	}
>  
>  	/*
> -- 
> 2.17.1
> 
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> libcamera-devel at lists.libcamera.org
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-- 
Regards,
Niklas Söderlund