Re: [PATCH v2 3/3] media: i2c: imx219: Only use higher LLP_MIN for binned resolutions

[Jacopo Mondi]

Hi Jai

On Fri, Feb 21, 2025 at 04:22:15PM +0530, Jai Luthra wrote:
> The LLP_MIN of 3560 is only needed to fix artefacts seen with binned
> resolutions. As increasing the LLP reduces the highest possible
> framerate by ~3%, use the old default minimum of 3448 if we are not
> doing 2x2 analog binning.
>
> Also restore the fll_def value for non-binned modes in the modes
> definition to restore the default mode framerate to 30fps.
>
> Suggested-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>
> Link: https://lore.kernel.org/linux-media/CAPY8ntC1-S6zKtDvmc6EgyxP+j6rTShuG8Dr8PKb9XQr2PeS_w@xxxxxxxxxxxxxx/
> Signed-off-by: Jai Luthra <jai.luthra@xxxxxxxxxxxxxxxx>
> ---
> Changes in v2:
>     - Fix the binning check, and only update the LLP minimum if we are
>       doing analog binning
>     - Add a note in the commit message for the fll_def value reverts
> ---
>  drivers/media/i2c/imx219.c | 28 +++++++++++++++++++---------
>  1 file changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c
> index 2081822533f9dff0a1ca93a09dd8333ec4043645..ec8d32b0f9e75b4b14d905b1e6b85180e5697ce1 100644
> --- a/drivers/media/i2c/imx219.c
> +++ b/drivers/media/i2c/imx219.c
> @@ -74,7 +74,8 @@
>  #define IMX219_FLL_MAX			0xffff
>  #define IMX219_VBLANK_MIN		32
>  #define IMX219_REG_LINE_LENGTH_A	CCI_REG16(0x0162)
> -#define IMX219_LLP_MIN			0x0de8
> +#define IMX219_LLP_MIN			0x0d78
> +#define IMX219_BINNED_LLP_MIN		0x0de8
>  #define IMX219_LLP_MAX			0x7ff0
>
>  #define IMX219_REG_X_ADD_STA_A		CCI_REG16(0x0164)
> @@ -311,13 +312,13 @@ static const struct imx219_mode supported_modes[] = {
>  		/* 8MPix 15fps mode */
>  		.width = 3280,
>  		.height = 2464,
> -		.fll_def = 3415,
> +		.fll_def = 3526,
>  	},
>  	{
>  		/* 1080P 30fps cropped */
>  		.width = 1920,
>  		.height = 1080,
> -		.fll_def = 1707,
> +		.fll_def = 1763,
>  	},
>  	{
>  		/* 2x2 binned 60fps mode */
> @@ -865,7 +866,7 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd,
>  	const struct imx219_mode *mode;
>  	struct v4l2_mbus_framefmt *format;
>  	struct v4l2_rect *crop;
> -	unsigned int bin_h, bin_v;
> +	u8 bin_h, bin_v;
>  	u32 prev_line_len;
>
>  	format = v4l2_subdev_state_get_format(state, 0);
> @@ -895,7 +896,7 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd,
>  	if (fmt->which == V4L2_SUBDEV_FORMAT_ACTIVE) {
>  		int exposure_max;
>  		int exposure_def;
> -		int hblank;
> +		int hblank, llp_min;

very minor nit: all other variables are declared one per line.

The rest looks good
Reviewed-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx>

Thanks
  j

>  		int pixel_rate;
>
>  		/* Update limits and set FPS to default */
> @@ -912,6 +913,19 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd,
>  					 imx219->exposure->minimum,
>  					 exposure_max, imx219->exposure->step,
>  					 exposure_def);
> +
> +		/*
> +		 * With analog binning the default minimum line length of 3448
> +		 * can cause artefacts with RAW10 formats, because the ADC
> +		 * operates on two lines together. So we switch to a higher
> +		 * minimum of 3560.
> +		 */
> +		imx219_get_binning(state, &bin_h, &bin_v);
> +		llp_min = (bin_h & bin_v) == IMX219_BINNING_X2_ANALOG ?
> +				  IMX219_BINNED_LLP_MIN : IMX219_LLP_MIN;
> +		__v4l2_ctrl_modify_range(imx219->hblank, llp_min - mode->width,
> +					 IMX219_LLP_MAX - mode->width, 1,
> +					 llp_min - mode->width);
>  		/*
>  		 * Retain PPL setting from previous mode so that the
>  		 * line time does not change on a mode change.
> @@ -920,10 +934,6 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd,
>  		 * mode width subtracted.
>  		 */
>  		hblank = prev_line_len - mode->width;
> -		__v4l2_ctrl_modify_range(imx219->hblank,
> -					 IMX219_LLP_MIN - mode->width,
> -					 IMX219_LLP_MAX - mode->width, 1,
> -					 IMX219_LLP_MIN - mode->width);
>  		__v4l2_ctrl_s_ctrl(imx219->hblank, hblank);
>
>  		/* Scale the pixel rate based on the mode specific factor */
>
> --
> 2.48.1
>