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From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Jacopo Mondi <jacopo+renesas@jmondi.org>
Cc:     magnus.damm@gmail.com, geert@glider.be, hverkuil@xs4all.nl,
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        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v9 11/11] media: i2c: ov7670: Fully set mbus frame fmt
Date:   Mon, 19 Feb 2018 21:19:32 +0200
Message-ID: <1963190.TI9O1pFqZp@avalon>
Organization: Ideas on Board Oy
In-Reply-To: <1519059584-30844-12-git-send-email-jacopo+renesas@jmondi.org>
References: <1519059584-30844-1-git-send-email-jacopo+renesas@jmondi.org> <1519059584-30844-12-git-send-email-jacopo+renesas@jmondi.org>
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Hi Jacopo,

Thank you for the patch.

On Monday, 19 February 2018 18:59:44 EET Jacopo Mondi wrote:
> The sensor driver sets mbus format colorspace information and sizes,
> but not ycbcr encoding, quantization and xfer function. When supplied
> with an badly initialized mbus frame format structure, those fields
> need to be set explicitly not to leave them uninitialized. This is
> tested by v4l2-compliance, which supplies a mbus format description
> structure and checks for all fields to be properly set.
> 
> Without this commit, v4l2-compliance fails when testing formats with:
> fail: v4l2-test-formats.cpp(335): ycbcr_enc >= 0xff
> 
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> ---
>  drivers/media/i2c/ov7670.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c
> index 25b26d4..61c472e 100644
> --- a/drivers/media/i2c/ov7670.c
> +++ b/drivers/media/i2c/ov7670.c
> @@ -996,6 +996,10 @@ static int ov7670_try_fmt_internal(struct v4l2_subdev
> *sd, fmt->height = wsize->height;
>  	fmt->colorspace = ov7670_formats[index].colorspace;

On a side note, if I'm not mistaken the colorspace field is set to SRGB for 
all entries. Shouldn't you hardcode it here and remove the field ?

> +	fmt->ycbcr_enc = V4L2_YCBCR_ENC_DEFAULT;
> +	fmt->quantization = V4L2_QUANTIZATION_DEFAULT;
> +	fmt->xfer_func = V4L2_XFER_FUNC_DEFAULT;

How about setting the values explicitly instead of relying on defaults ? That 
would be V4L2_YCBCR_ENC_601, V4L2_QUANTIZATION_LIM_RANGE and 
V4L2_XFER_FUNC_SRGB. And could you then check a captured frame to see if the 
sensor outputs limited or full range ?

>  	info->format = *fmt;
> 
>  	return 0;

-- 
Regards,

Laurent Pinchart