Re: [PATCH v2 1/2] media: i2c: ov13b10: Fix h_blank calculation

[Hans de Goede <hdegoede@redhat.com>]

Hi Hao,

On 11-Mar-25 9:46 AM, Hao Yao wrote:
> Pixel per line (PPL) is calculated as pixel_rate / (VTS * FPS), which
> is not decided by MIPI CSI-2 link frequency. PPL can vary while link
> frequency keeps the same. If PPL is wrong, the h_blank = PPL - width
> is also wrong then FPS control is inaccurate.
> 
> This patch fix h_blank by:
> 1. Move PPL from link_freq_config to ov13b10_mode
> 2. Add PPL value for different modes
> 3. Use PPL from mode to calculate h_blank
> 
> Signed-off-by: Bingbu Cao <bingbu.cao@intel.com>
> Signed-off-by: Hao Yao <hao.yao@intel.com>
> ---
>  drivers/media/i2c/ov13b10.c | 36 ++++++++++++++++++------------------
>  1 file changed, 18 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov13b10.c b/drivers/media/i2c/ov13b10.c
> index 73c844aa5697..2e83fc23f321 100644
> --- a/drivers/media/i2c/ov13b10.c
> +++ b/drivers/media/i2c/ov13b10.c
> @@ -34,9 +34,6 @@
>  #define OV13B10_VTS_120FPS		0x0320
>  #define OV13B10_VTS_MAX			0x7fff
>  
> -/* HBLANK control - read only */
> -#define OV13B10_PPL_560MHZ		4704
> -
>  /* Exposure control */
>  #define OV13B10_REG_EXPOSURE		0x3500
>  #define OV13B10_EXPOSURE_MIN		4
> @@ -95,7 +92,7 @@ struct ov13b10_reg_list {
>  
>  /* Link frequency config */
>  struct ov13b10_link_freq_config {
> -	u32 pixels_per_line;
> +	u64 link_freq;
>  
>  	/* registers for this link frequency */
>  	struct ov13b10_reg_list reg_list;
> @@ -114,6 +111,10 @@ struct ov13b10_mode {
>  
>  	/* Index of Link frequency config to be used */
>  	u32 link_freq_index;
> +
> +	/* Pixels per line in current mode */
> +	u32 ppl;
> +
>  	/* Default register values */
>  	struct ov13b10_reg_list reg_list;
>  };
> @@ -549,7 +550,7 @@ static const s64 link_freq_menu_items[] = {
>  static const struct ov13b10_link_freq_config
>  			link_freq_configs[] = {
>  	{
> -		.pixels_per_line = OV13B10_PPL_560MHZ,
> +		.link_freq = OV13B10_LINK_FREQ_560MHZ,
>  		.reg_list = {
>  			.num_of_regs = ARRAY_SIZE(mipi_data_rate_1120mbps),
>  			.regs = mipi_data_rate_1120mbps,
> @@ -564,6 +565,7 @@ static const struct ov13b10_mode supported_modes[] = {
>  		.height = 3120,
>  		.vts_def = OV13B10_VTS_30FPS,
>  		.vts_min = OV13B10_VTS_30FPS,
> +		.ppl = 4704,
>  		.reg_list = {
>  			.num_of_regs = ARRAY_SIZE(mode_4208x3120_regs),
>  			.regs = mode_4208x3120_regs,
> @@ -575,6 +577,7 @@ static const struct ov13b10_mode supported_modes[] = {
>  		.height = 3120,
>  		.vts_def = OV13B10_VTS_30FPS,
>  		.vts_min = OV13B10_VTS_30FPS,
> +		.ppl = 4704,
>  		.reg_list = {
>  			.num_of_regs = ARRAY_SIZE(mode_4160x3120_regs),
>  			.regs = mode_4160x3120_regs,
> @@ -586,6 +589,7 @@ static const struct ov13b10_mode supported_modes[] = {
>  		.height = 2340,
>  		.vts_def = OV13B10_VTS_30FPS,
>  		.vts_min = OV13B10_VTS_30FPS,
> +		.ppl = 4704,
>  		.reg_list = {
>  			.num_of_regs = ARRAY_SIZE(mode_4160x2340_regs),
>  			.regs = mode_4160x2340_regs,
> @@ -597,6 +601,7 @@ static const struct ov13b10_mode supported_modes[] = {
>  		.height = 1560,
>  		.vts_def = OV13B10_VTS_60FPS,
>  		.vts_min = OV13B10_VTS_60FPS,
> +		.ppl = 4704,
>  		.reg_list = {
>  			.num_of_regs = ARRAY_SIZE(mode_2104x1560_regs),
>  			.regs = mode_2104x1560_regs,
> @@ -608,6 +613,7 @@ static const struct ov13b10_mode supported_modes[] = {
>  		.height = 1170,
>  		.vts_def = OV13B10_VTS_60FPS,
>  		.vts_min = OV13B10_VTS_60FPS,
> +		.ppl = 4704,
>  		.reg_list = {
>  			.num_of_regs = ARRAY_SIZE(mode_2080x1170_regs),
>  			.regs = mode_2080x1170_regs,
> @@ -620,6 +626,7 @@ static const struct ov13b10_mode supported_modes[] = {
>  		.vts_def = OV13B10_VTS_120FPS,
>  		.vts_min = OV13B10_VTS_120FPS,
>  		.link_freq_index = OV13B10_LINK_FREQ_INDEX_0,
> +		.ppl = 4664,
>  		.reg_list = {
>  			.num_of_regs = ARRAY_SIZE(mode_1364x768_120fps_regs),
>  			.regs = mode_1364x768_120fps_regs,
> @@ -1062,19 +1069,13 @@ ov13b10_set_pad_format(struct v4l2_subdev *sd,
>  		__v4l2_ctrl_s_ctrl_int64(ov13b->pixel_rate, pixel_rate);
>  
>  		/* Update limits and set FPS to default */
> -		vblank_def = ov13b->cur_mode->vts_def -
> -			     ov13b->cur_mode->height;
> -		vblank_min = ov13b->cur_mode->vts_min -
> -			     ov13b->cur_mode->height;
> +		vblank_def = mode->vts_def - mode->height;
> +		vblank_min = mode->vts_min - mode->height;
>  		__v4l2_ctrl_modify_range(ov13b->vblank, vblank_min,
> -					 OV13B10_VTS_MAX
> -					 - ov13b->cur_mode->height,
> -					 1,
> -					 vblank_def);
> +					 OV13B10_VTS_MAX - mode->height,
> +					 1, vblank_def);
>  		__v4l2_ctrl_s_ctrl(ov13b->vblank, vblank_def);
> -		h_blank =
> -			link_freq_configs[mode->link_freq_index].pixels_per_line
> -			 - ov13b->cur_mode->width;
> +		h_blank = mode->ppl - mode->width;
>  		__v4l2_ctrl_modify_range(ov13b->hblank, h_blank,
>  					 h_blank, 1, h_blank);
>  	}

You are doing a bunch of unrelated search 'ov13b->cur_mode->' replace
with 'mode->' here e.g. for vblank_def and vblank_min. While this is
a good change to have which increases readability, this is unrelated
to the hblank changes, so please split this out into a new patch 1/3
as preparation for the further changes in the series.

Mixing those changes into this patch makes it hard for reviewers to
see which changes you are actually making wrt h_blank handling.

Regards,

Hans


> @@ -1328,8 +1329,7 @@ static int ov13b10_init_controls(struct ov13b10 *ov13b)
>  					  OV13B10_VTS_MAX - mode->height, 1,
>  					  vblank_def);
>  
> -	hblank = link_freq_configs[mode->link_freq_index].pixels_per_line -
> -		 mode->width;
> +	hblank = mode->ppl - mode->width;
>  	ov13b->hblank = v4l2_ctrl_new_std(ctrl_hdlr, &ov13b10_ctrl_ops,
>  					  V4L2_CID_HBLANK,
>  					  hblank, hblank, 1, hblank);