Re: [PATCH V2] v4l: OMAP3 ISP CCDC: Add support for 8bit greyscale sensors

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Martin,

Thanks for the patch. One comment below.

On Tuesday 18 January 2011 22:27:42 Martin Hostettler wrote:
> Adds support for V4L2_MBUS_FMT_Y8_1X8 format and 8bit data width in
> synchronous interface.
> 
> When in 8bit mode don't apply DC substraction of 64 per default as this
> would remove 1/4 of the sensor range.
> 
> When using V4L2_MBUS_FMT_Y8_1X8 (or possibly another 8bit per pixel) mode
> set the CDCC to output 8bit per pixel instead of 16bit.
> 
> Signed-off-by: Martin Hostettler <martin@neutronstar.dyndns.org>
> ---
>  drivers/media/video/isp/ispccdc.c  |   22 ++++++++++++++++++----
>  drivers/media/video/isp/ispvideo.c |    2 ++
>  2 files changed, 20 insertions(+), 4 deletions(-)
> 
> Changes since first version:
> 	- forward ported to current media.git
> 
> diff --git a/drivers/media/video/isp/ispccdc.c
> b/drivers/media/video/isp/ispccdc.c index 578c8bf..c7397c9 100644
> --- a/drivers/media/video/isp/ispccdc.c
> +++ b/drivers/media/video/isp/ispccdc.c
> @@ -43,6 +43,7 @@ __ccdc_get_format(struct isp_ccdc_device *ccdc, struct
> v4l2_subdev_fh *fh, unsigned int pad, enum v4l2_subdev_format_whence
> which);
> 
>  static const unsigned int ccdc_fmts[] = {
> +	V4L2_MBUS_FMT_Y8_1X8,
>  	V4L2_MBUS_FMT_SGRBG10_1X10,
>  	V4L2_MBUS_FMT_SRGGB10_1X10,
>  	V4L2_MBUS_FMT_SBGGR10_1X10,
> @@ -1127,6 +1128,9 @@ static void ccdc_configure(struct isp_ccdc_device
> *ccdc) ccdc->syncif.datsz = pdata ? pdata->width : 10;
>  	ispccdc_config_sync_if(ccdc, &ccdc->syncif);
> 
> +	/* CCDC_PAD_SINK */
> +	format = &ccdc->formats[CCDC_PAD_SINK];
> +
>  	syn_mode = isp_reg_readl(isp, OMAP3_ISP_IOMEM_CCDC, ISPCCDC_SYN_MODE);
> 
>  	/* Use the raw, unprocessed data when writing to memory. The H3A and
> @@ -1144,10 +1148,15 @@ static void ccdc_configure(struct isp_ccdc_device
> *ccdc) else
>  		syn_mode &= ~ISPCCDC_SYN_MODE_SDR2RSZ;
> 
> -	isp_reg_writel(isp, syn_mode, OMAP3_ISP_IOMEM_CCDC, ISPCCDC_SYN_MODE);
> +	/* Use PACK8 mode for 1byte per pixel formats */
> 
> -	/* CCDC_PAD_SINK */
> -	format = &ccdc->formats[CCDC_PAD_SINK];
> +	if (isp_video_format_info(format->code)->bpp <= 8)
> +		syn_mode |= ISPCCDC_SYN_MODE_PACK8;
> +	else
> +		syn_mode &= ~ISPCCDC_SYN_MODE_PACK8;
> +
> +
> +	isp_reg_writel(isp, syn_mode, OMAP3_ISP_IOMEM_CCDC, ISPCCDC_SYN_MODE);
> 
>  	/* Mosaic filter */
>  	switch (format->code) {
> @@ -2244,7 +2253,12 @@ int isp_ccdc_init(struct isp_device *isp)
>  	ccdc->syncif.vdpol = 0;
> 
>  	ccdc->clamp.oblen = 0;
> -	ccdc->clamp.dcsubval = 64;
> +
> +	if (isp->pdata->subdevs->interface == ISP_INTERFACE_PARALLEL
> +	    && isp->pdata->subdevs->bus.parallel.width <= 8)
> +		ccdc->clamp.dcsubval = 0;
> +	else
> +		ccdc->clamp.dcsubval = 64;

I don't like this too much. What happens if you have several sensors connected 
to the system with different bus width ?

>  	ccdc->vpcfg.pixelclk = 0;
> 
> diff --git a/drivers/media/video/isp/ispvideo.c
> b/drivers/media/video/isp/ispvideo.c index 5f984e4..cd3d331 100644
> --- a/drivers/media/video/isp/ispvideo.c
> +++ b/drivers/media/video/isp/ispvideo.c
> @@ -221,6 +221,8 @@ isp_video_check_format(struct isp_video *video, struct
> isp_video_fh *vfh) }
> 
>  static struct isp_format_info formats[] = {
> +	{ V4L2_MBUS_FMT_Y8_1X8, V4L2_MBUS_FMT_Y8_1X8,
> +	  V4L2_MBUS_FMT_Y8_1X8, V4L2_PIX_FMT_GREY, 8, },
>  	{ V4L2_MBUS_FMT_SGRBG10_DPCM8_1X8, V4L2_MBUS_FMT_SGRBG10_DPCM8_1X8,
>  	  V4L2_MBUS_FMT_SGRBG10_1X10, V4L2_PIX_FMT_SGRBG10DPCM8, 8, },
>  	{ V4L2_MBUS_FMT_SBGGR10_1X10, V4L2_MBUS_FMT_SBGGR10_1X10,

-- 
Regards,

Laurent Pinchart