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Date: Thu, 28 Mar 2024 08:09:48 +0000
From: Sakari Ailus <sakari.ailus@linux.intel.com>
To: git@luigi311.com
Cc: linux-media@vger.kernel.org, dave.stevenson@raspberrypi.com,
	jacopo.mondi@ideasonboard.com, mchehab@kernel.org, robh@kernel.org,
	krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org,
	shawnguo@kernel.org, s.hauer@pengutronix.de, kernel@pengutronix.de,
	festevam@gmail.com, devicetree@vger.kernel.org, imx@lists.linux.dev,
	linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 08/23] media: i2c: imx258: Add support for 24MHz clock
Message-ID: <ZgUlzCfUN-PnF8Yy@kekkonen.localdomain>
References: <20240327231710.53188-1-git@luigi311.com>
 <20240327231710.53188-9-git@luigi311.com>
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In-Reply-To: <20240327231710.53188-9-git@luigi311.com>

Hi Luigi311,

Thank you for the patchset.

On Wed, Mar 27, 2024 at 05:16:54PM -0600, git@luigi311.com wrote:
> From: Dave Stevenson <dave.stevenson@raspberrypi.com>
> 
> There's no reason why only a clock of 19.2MHz is supported.
> Indeed this isn't even a frequency listed in the datasheet.
> 
> Add support for 24MHz as well.
> The PLL settings result in slightly different link frequencies,
> so parameterise those.
> 
> Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
> Signed-off-by: Luigi311 <git@luigi311.com>

Is Luigi311 your real name? As per
Documentation/process/submitting-patches.rst, anonymous (or pseudonym I'd
say as well) contributions are not an option.

> ---
>  drivers/media/i2c/imx258.c | 133 +++++++++++++++++++++++++++++--------
>  1 file changed, 107 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/media/i2c/imx258.c b/drivers/media/i2c/imx258.c
> index 351add1bc5d5..6ee7de079454 100644
> --- a/drivers/media/i2c/imx258.c
> +++ b/drivers/media/i2c/imx258.c
> @@ -76,9 +76,6 @@
>  #define REG_CONFIG_MIRROR_FLIP		0x03
>  #define REG_CONFIG_FLIP_TEST_PATTERN	0x02
>  
> -/* Input clock frequency in Hz */
> -#define IMX258_INPUT_CLOCK_FREQ		19200000
> -
>  struct imx258_reg {
>  	u16 address;
>  	u8 val;
> @@ -115,7 +112,9 @@ struct imx258_mode {
>  };
>  
>  /* 4208x3120 needs 1267Mbps/lane, 4 lanes */
> -static const struct imx258_reg mipi_data_rate_1267mbps[] = {
> +static const struct imx258_reg mipi_1267mbps_19_2mhz[] = {
> +	{ 0x0136, 0x13 },
> +	{ 0x0137, 0x33 },
>  	{ 0x0301, 0x05 },
>  	{ 0x0303, 0x02 },
>  	{ 0x0305, 0x03 },
> @@ -133,7 +132,29 @@ static const struct imx258_reg mipi_data_rate_1267mbps[] = {
>  	{ 0x0823, 0xCC },
>  };
>  
> -static const struct imx258_reg mipi_data_rate_640mbps[] = {
> +static const struct imx258_reg mipi_1272mbps_24mhz[] = {
> +	{ 0x0136, 0x18 },
> +	{ 0x0137, 0x00 },
> +	{ 0x0301, 0x05 },
> +	{ 0x0303, 0x02 },
> +	{ 0x0305, 0x04 },
> +	{ 0x0306, 0x00 },
> +	{ 0x0307, 0xD4 },
> +	{ 0x0309, 0x0A },
> +	{ 0x030B, 0x01 },
> +	{ 0x030D, 0x02 },
> +	{ 0x030E, 0x00 },
> +	{ 0x030F, 0xD8 },
> +	{ 0x0310, 0x00 },
> +	{ 0x0820, 0x13 },
> +	{ 0x0821, 0x4C },
> +	{ 0x0822, 0xCC },
> +	{ 0x0823, 0xCC },
> +};
> +
> +static const struct imx258_reg mipi_640mbps_19_2mhz[] = {
> +	{ 0x0136, 0x13 },
> +	{ 0x0137, 0x33 },
>  	{ 0x0301, 0x05 },
>  	{ 0x0303, 0x02 },
>  	{ 0x0305, 0x03 },
> @@ -151,9 +172,27 @@ static const struct imx258_reg mipi_data_rate_640mbps[] = {
>  	{ 0x0823, 0x00 },
>  };
>  
> +static const struct imx258_reg mipi_642mbps_24mhz[] = {
> +	{ 0x0136, 0x18 },
> +	{ 0x0137, 0x00 },
> +	{ 0x0301, 0x05 },
> +	{ 0x0303, 0x02 },
> +	{ 0x0305, 0x04 },
> +	{ 0x0306, 0x00 },
> +	{ 0x0307, 0x6B },
> +	{ 0x0309, 0x0A },
> +	{ 0x030B, 0x01 },
> +	{ 0x030D, 0x02 },
> +	{ 0x030E, 0x00 },
> +	{ 0x030F, 0xD8 },
> +	{ 0x0310, 0x00 },
> +	{ 0x0820, 0x0A },
> +	{ 0x0821, 0x00 },
> +	{ 0x0822, 0x00 },
> +	{ 0x0823, 0x00 },
> +};
> +
>  static const struct imx258_reg mode_common_regs[] = {
> -	{ 0x0136, 0x13 },
> -	{ 0x0137, 0x33 },
>  	{ 0x3051, 0x00 },
>  	{ 0x3052, 0x00 },
>  	{ 0x4E21, 0x14 },
> @@ -313,10 +352,6 @@ static const char * const imx258_supply_name[] = {
>  
>  #define IMX258_NUM_SUPPLIES ARRAY_SIZE(imx258_supply_name)
>  
> -/* Configurations for supported link frequencies */
> -#define IMX258_LINK_FREQ_634MHZ	633600000ULL
> -#define IMX258_LINK_FREQ_320MHZ	320000000ULL
> -
>  enum {
>  	IMX258_LINK_FREQ_1267MBPS,
>  	IMX258_LINK_FREQ_640MBPS,
> @@ -335,25 +370,55 @@ static u64 link_freq_to_pixel_rate(u64 f)
>  }
>  
>  /* Menu items for LINK_FREQ V4L2 control */
> -static const s64 link_freq_menu_items[] = {
> +/* Configurations for supported link frequencies */
> +#define IMX258_LINK_FREQ_634MHZ	633600000ULL
> +#define IMX258_LINK_FREQ_320MHZ	320000000ULL
> +
> +static const s64 link_freq_menu_items_19_2[] = {
>  	IMX258_LINK_FREQ_634MHZ,
>  	IMX258_LINK_FREQ_320MHZ,
>  };
>  
> +/* Configurations for supported link frequencies */
> +#define IMX258_LINK_FREQ_636MHZ	636000000ULL
> +#define IMX258_LINK_FREQ_321MHZ	321000000ULL

These values aren't used outside the array below and the macro names are
imprecise anyway. Could you put the numerical values to the array instead?

> +
> +static const s64 link_freq_menu_items_24[] = {
> +	IMX258_LINK_FREQ_636MHZ,
> +	IMX258_LINK_FREQ_321MHZ,
> +};
> +
>  /* Link frequency configs */
> -static const struct imx258_link_freq_config link_freq_configs[] = {
> +static const struct imx258_link_freq_config link_freq_configs_19_2[] = {
>  	[IMX258_LINK_FREQ_1267MBPS] = {
>  		.pixels_per_line = IMX258_PPL_DEFAULT,
>  		.reg_list = {
> -			.num_of_regs = ARRAY_SIZE(mipi_data_rate_1267mbps),
> -			.regs = mipi_data_rate_1267mbps,
> +			.num_of_regs = ARRAY_SIZE(mipi_1267mbps_19_2mhz),
> +			.regs = mipi_1267mbps_19_2mhz,
>  		}
>  	},
>  	[IMX258_LINK_FREQ_640MBPS] = {
>  		.pixels_per_line = IMX258_PPL_DEFAULT,
>  		.reg_list = {
> -			.num_of_regs = ARRAY_SIZE(mipi_data_rate_640mbps),
> -			.regs = mipi_data_rate_640mbps,
> +			.num_of_regs = ARRAY_SIZE(mipi_640mbps_19_2mhz),
> +			.regs = mipi_640mbps_19_2mhz,
> +		}
> +	},
> +};
> +
> +static const struct imx258_link_freq_config link_freq_configs_24[] = {
> +	[IMX258_LINK_FREQ_1267MBPS] = {
> +		.pixels_per_line = IMX258_PPL_DEFAULT,
> +		.reg_list = {
> +			.num_of_regs = ARRAY_SIZE(mipi_1272mbps_24mhz),
> +			.regs = mipi_1272mbps_24mhz,
> +		}
> +	},
> +	[IMX258_LINK_FREQ_640MBPS] = {
> +		.pixels_per_line = IMX258_PPL_DEFAULT,
> +		.reg_list = {
> +			.num_of_regs = ARRAY_SIZE(mipi_642mbps_24mhz),
> +			.regs = mipi_642mbps_24mhz,
>  		}
>  	},
>  };
> @@ -410,6 +475,9 @@ struct imx258 {
>  	/* Current mode */
>  	const struct imx258_mode *cur_mode;
>  
> +	const struct imx258_link_freq_config *link_freq_configs;
> +	const s64 *link_freq_menu_items;
> +
>  	/*
>  	 * Mutex for serialized access:
>  	 * Protect sensor module set pad format and start/stop streaming safely.
> @@ -713,7 +781,7 @@ static int imx258_set_pad_format(struct v4l2_subdev *sd,
>  		imx258->cur_mode = mode;
>  		__v4l2_ctrl_s_ctrl(imx258->link_freq, mode->link_freq_index);
>  
> -		link_freq = link_freq_menu_items[mode->link_freq_index];
> +		link_freq = imx258->link_freq_menu_items[mode->link_freq_index];
>  		pixel_rate = link_freq_to_pixel_rate(link_freq);
>  		__v4l2_ctrl_s_ctrl_int64(imx258->pixel_rate, pixel_rate);
>  		/* Update limits and set FPS to default */
> @@ -727,7 +795,7 @@ static int imx258_set_pad_format(struct v4l2_subdev *sd,
>  			vblank_def);
>  		__v4l2_ctrl_s_ctrl(imx258->vblank, vblank_def);
>  		h_blank =
> -			link_freq_configs[mode->link_freq_index].pixels_per_line
> +			imx258->link_freq_configs[mode->link_freq_index].pixels_per_line
>  			 - imx258->cur_mode->width;
>  		__v4l2_ctrl_modify_range(imx258->hblank, h_blank,
>  					 h_blank, 1, h_blank);
> @@ -747,7 +815,7 @@ static int imx258_start_streaming(struct imx258 *imx258)
>  
>  	/* Setup PLL */
>  	link_freq_index = imx258->cur_mode->link_freq_index;
> -	reg_list = &link_freq_configs[link_freq_index].reg_list;
> +	reg_list = &imx258->link_freq_configs[link_freq_index].reg_list;
>  	ret = imx258_write_regs(imx258, reg_list->regs, reg_list->num_of_regs);
>  	if (ret) {
>  		dev_err(&client->dev, "%s failed to set plls\n", __func__);
> @@ -946,9 +1014,9 @@ static int imx258_init_controls(struct imx258 *imx258)
>  	imx258->link_freq = v4l2_ctrl_new_int_menu(ctrl_hdlr,
>  				&imx258_ctrl_ops,
>  				V4L2_CID_LINK_FREQ,
> -				ARRAY_SIZE(link_freq_menu_items) - 1,
> +				ARRAY_SIZE(link_freq_menu_items_19_2) - 1,
>  				0,
> -				link_freq_menu_items);
> +				imx258->link_freq_menu_items);
>  
>  	if (imx258->link_freq)
>  		imx258->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> @@ -964,8 +1032,10 @@ static int imx258_init_controls(struct imx258 *imx258)
>  	if (vflip)
>  		vflip->flags |= V4L2_CTRL_FLAG_READ_ONLY;
>  
> -	pixel_rate_max = link_freq_to_pixel_rate(link_freq_menu_items[0]);
> -	pixel_rate_min = link_freq_to_pixel_rate(link_freq_menu_items[1]);
> +	pixel_rate_max =
> +		link_freq_to_pixel_rate(imx258->link_freq_menu_items[0]);
> +	pixel_rate_min =
> +		link_freq_to_pixel_rate(imx258->link_freq_menu_items[1]);

The arrays currently have two entries so this works but it'd nice to have a
bit more robust way to handle differences between the two arrays. Could you
maintain e.g. the number of entries in the array in a struct field perhaps?

>  	/* By default, PIXEL_RATE is read only */
>  	imx258->pixel_rate = v4l2_ctrl_new_std(ctrl_hdlr, &imx258_ctrl_ops,
>  				V4L2_CID_PIXEL_RATE,
> @@ -1086,8 +1156,19 @@ static int imx258_probe(struct i2c_client *client)
>  	} else {
>  		val = clk_get_rate(imx258->clk);
>  	}
> -	if (val != IMX258_INPUT_CLOCK_FREQ) {
> -		dev_err(&client->dev, "input clock frequency not supported\n");
> +
> +	switch (val) {
> +	case 19200000:
> +		imx258->link_freq_configs = link_freq_configs_19_2;
> +		imx258->link_freq_menu_items = link_freq_menu_items_19_2;
> +		break;
> +	case 24000000:
> +		imx258->link_freq_configs = link_freq_configs_24;
> +		imx258->link_freq_menu_items = link_freq_menu_items_24;
> +		break;
> +	default:
> +		dev_err(&client->dev, "input clock frequency of %u not supported\n",
> +			val);
>  		return -EINVAL;
>  	}
>  

-- 
Kind regards,

Sakari Ailus