linux-kernel - Re: [PATCH v6 4/5] media: i2c: imx219: Increase minimum LLP to fix blocky artefacts

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Message-ID: <j4gczp5ch3cz5tvnjolnhwda4vqyztyq24p37ncqaephc45lo2@273oss3pilee>
Date: Fri, 7 Feb 2025 17:07:07 +0100
From: Jacopo Mondi <jacopo.mondi@...asonboard.com>
To: Jai Luthra <jai.luthra@...asonboard.com>
Cc: Dave Stevenson <dave.stevenson@...pberrypi.com>, 
	Sakari Ailus <sakari.ailus@...ux.intel.com>, Mauro Carvalho Chehab <mchehab@...nel.org>, 
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Jacopo Mondi <jacopo.mondi@...asonboard.com>, Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH v6 4/5] media: i2c: imx219: Increase minimum LLP to fix
 blocky artefacts

Hi Jai

On Tue, Feb 04, 2025 at 12:34:39PM +0530, Jai Luthra wrote:
> The sensor's internal ADC supports a minimum line length of 3448 pixels,
> which may be too small to use with analog binning, where ADC operates on
> two lines together. Switch to a higher minimum line length of 3560
> pixels to fix the blocky artefacts seen with analog binning [1].
>

Very nice finding!

If the new value differs from the default register value in the
datahseet, can we record the reason with a comment ?

> To keep the same default framerate as before for all the modes, lower
> the default fll value to compensate for the increase in llp.

Thanks for handling this

This seems fine to me
Reviewed-by: Jacopo Mondi <jacopo.mondi@...asonboard.com>

Thanks
  j

>
> [1]: https://github.com/raspberrypi/rpicam-apps/issues/281#issuecomment-1082894118
>
> Signed-off-by: Jai Luthra <jai.luthra@...asonboard.com>
> ---
>  drivers/media/i2c/imx219.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c
> index 8239e7ea8ec03849b339c1f314485266d4c4d8bd..e4aa6e66b673bb7a8942bf8daf27267c2884ec95 100644
> --- a/drivers/media/i2c/imx219.c
> +++ b/drivers/media/i2c/imx219.c
> @@ -74,7 +74,7 @@
>  #define IMX219_FLL_MAX			0xffff
>  #define IMX219_VBLANK_MIN		32
>  #define IMX219_REG_LINE_LENGTH_A	CCI_REG16(0x0162)
> -#define IMX219_LLP_MIN			0x0d78
> +#define IMX219_LLP_MIN			0x0de8
>  #define IMX219_LLP_MAX			0x7ff0
>
>  #define IMX219_REG_X_ADD_STA_A		CCI_REG16(0x0164)
> @@ -286,25 +286,25 @@ static const struct imx219_mode supported_modes[] = {
>  		/* 8MPix 15fps mode */
>  		.width = 3280,
>  		.height = 2464,
> -		.fll_def = 3526,
> +		.fll_def = 3415,
>  	},
>  	{
>  		/* 1080P 30fps cropped */
>  		.width = 1920,
>  		.height = 1080,
> -		.fll_def = 1763,
> +		.fll_def = 1707,
>  	},
>  	{
>  		/* 2x2 binned 30fps mode */
>  		.width = 1640,
>  		.height = 1232,
> -		.fll_def = 1763,
> +		.fll_def = 1707,
>  	},
>  	{
>  		/* 640x480 30fps mode */
>  		.width = 640,
>  		.height = 480,
> -		.fll_def = 1763,
> +		.fll_def = 1707,
>  	},
>  };
>
>
> --
> 2.48.1
>