linux-kernel - Re: [PATCH v8 01/14] media: videodev2.h, v4l2-ioctl: add rkisp1 meta buffer format

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Date:   Thu, 15 Aug 2019 16:30:51 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Helen Koike <helen.koike@...labora.com>
Cc:     linux-rockchip@...ts.infradead.org, devicetree@...r.kernel.org,
        eddie.cai.linux@...il.com, mchehab@...nel.org, heiko@...ech.de,
        jacob2.chen@...k-chips.com, jeffy.chen@...k-chips.com,
        zyc@...k-chips.com, linux-kernel@...r.kernel.org,
        tfiga@...omium.org, hans.verkuil@...co.com,
        sakari.ailus@...ux.intel.com, kernel@...labora.com,
        ezequiel@...labora.com, linux-media@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, zhengsq@...k-chips.com
Subject: Re: [PATCH v8 01/14] media: videodev2.h, v4l2-ioctl: add rkisp1 meta
 buffer format

Hi Helen,

Thank you for the patch.

On Tue, Jul 30, 2019 at 03:42:43PM -0300, Helen Koike wrote:
> From: Shunqian Zheng <zhengsq@...k-chips.com>
> 
> Add the Rockchip ISP1 specific processing parameter format
> V4L2_META_FMT_RK_ISP1_PARAMS and metadata format
> V4L2_META_FMT_RK_ISP1_STAT_3A for 3A.

I don't like V4L2_META_FMT_RK_ISP1_PARAMS much, as the parameters are
not passed to the hardware through a buffer, but instead written to
registers by the kernel driver. This is an area where V4L2 controls are
traditionally used. I do however understand that it's easier for driver
authors to pass a large set of controls this way when they have to be
applied atomically, but it's clearly a hack in my opinion. I won't
oppose to it though, as I know there's no way we can support this kind
of feature in V4L2 at the moment without an extensive amount of work, so

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> Signed-off-by: Shunqian Zheng <zhengsq@...k-chips.com>
> Signed-off-by: Jacob Chen <jacob2.chen@...k-chips.com>
> Acked-by: Hans Verkuil <hans.verkuil@...co.com>
> [update for upstream]
> Signed-off-by: Helen Koike <helen.koike@...labora.com>
> 
> ---
> 
> Changes in v8: None
> Changes in v7:
> - s/IPU3/RK_ISP1
> 
>  drivers/media/v4l2-core/v4l2-ioctl.c | 2 ++
>  include/uapi/linux/videodev2.h       | 4 ++++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index bb5b4926538a..2df20801a299 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -1330,6 +1330,8 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
>  	case V4L2_META_FMT_VSP1_HGT:	descr = "R-Car VSP1 2-D Histogram"; break;
>  	case V4L2_META_FMT_UVC:		descr = "UVC Payload Header Metadata"; break;
>  	case V4L2_META_FMT_D4XX:	descr = "Intel D4xx UVC Metadata"; break;
> +	case V4L2_META_FMT_RK_ISP1_PARAMS:	descr = "Rockchip ISP1 3A params"; break;
> +	case V4L2_META_FMT_RK_ISP1_STAT_3A:	descr = "Rockchip ISP1 3A statistics"; break;
>  
>  	default:
>  		/* Compressed formats */
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 2427bc4d8eba..ae1e375a10d7 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -756,6 +756,10 @@ struct v4l2_pix_format {
>  #define V4L2_META_FMT_UVC         v4l2_fourcc('U', 'V', 'C', 'H') /* UVC Payload Header metadata */
>  #define V4L2_META_FMT_D4XX        v4l2_fourcc('D', '4', 'X', 'X') /* D4XX Payload Header metadata */
>  
> +/* Vendor specific - used for RK_ISP1 camera sub-system */
> +#define V4L2_META_FMT_RK_ISP1_PARAMS	v4l2_fourcc('R', 'K', '1', 'P') /* Rockchip ISP1 params */
> +#define V4L2_META_FMT_RK_ISP1_STAT_3A	v4l2_fourcc('R', 'K', '1', 'S') /* Rockchip ISP1 3A statistics */
> +
>  /* priv field value to indicates that subsequent fields are valid. */
>  #define V4L2_PIX_FMT_PRIV_MAGIC		0xfeedcafe
>  

-- 
Regards,

Laurent Pinchart