Re: [PATCH v2 04/12] media: i2c: Support 19.2MHz input clock in ov8865

Sakari Ailus
2021-08-10T13:34:35Z

Hi Daniel,

Thanks for the set.

On Mon, Aug 09, 2021 at 11:58:37PM +0100, Daniel Scally wrote:
> The ov8865 driver as written expects a 24MHz input clock, but the sensor
> is sometimes found on x86 platforms with a 19.2MHz input clock supplied.
> Add a set of PLL configurations to the driver to support that rate too.
> As ACPI doesn't auto-configure the clock rate, check for a clock-frequency
> during probe and set that rate if one is found.
>
> Signed-off-by: Daniel Scally <djrscally@gmail.com>
> ---
> Changes in v2:
>
> - Added an enum defining the possible frequency rates to index the
> array (Andy)
>
> drivers/media/i2c/ov8865.c | 164 +++++++++++++++++++++++++++----------
> 1 file changed, 121 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/media/i2c/ov8865.c b/drivers/media/i2c/ov8865.c
> index fe700787bfb9..1382b16d1a09 100644
> --- a/drivers/media/i2c/ov8865.c
> +++ b/drivers/media/i2c/ov8865.c
> @@ -21,10 +21,6 @@
> #include <media/v4l2-image-sizes.h>
> #include <media/v4l2-mediabus.h>
>
> -/* Clock rate */
> -
> -#define OV8865_EXTCLK_RATE 24000000
> -
> /* Register definitions */
>
> /* System */
> @@ -567,6 +563,19 @@ struct ov8865_sclk_config {
> unsigned int sclk_div;
> };
>
> +/* Clock rate */
> +
> +enum extclk_rate {
> + OV8865_19_2_MHZ,
> + OV8865_24_MHZ,
> + OV8865_NUM_SUPPORTED_RATES,
> +};
> +
> +static const unsigned long supported_extclk_rates[] = {
> + [OV8865_19_2_MHZ] = 19200000,
> + [OV8865_24_MHZ] = 24000000,
> +};
> +
> /*
> * General formulas for (array-centered) mode calculation:
> * - photo_array_width = 3296
> @@ -665,6 +674,9 @@ struct ov8865_sensor {
> struct regulator *avdd;
> struct regulator *dvdd;
> struct regulator *dovdd;
> +
> + unsigned long extclk_rate;
> + enum extclk_rate extclk_rate_idx;
> struct clk *extclk;
>
> struct v4l2_fwnode_endpoint endpoint;
> @@ -680,49 +692,83 @@ struct ov8865_sensor {
> /* Static definitions */
>
> /*
> - * EXTCLK = 24 MHz
> * PHY_SCLK = 720 MHz
> * MIPI_PCLK = 90 MHz
> */
> -static const struct ov8865_pll1_config ov8865_pll1_config_native = {
> - .pll_pre_div_half = 1,
> - .pll_pre_div = 0,
> - .pll_mul = 30,
> - .m_div = 1,
> - .mipi_div = 3,
> - .pclk_div = 1,
> - .sys_pre_div = 1,
> - .sys_div = 2,
> +
> +static const struct ov8865_pll1_config ov8865_pll1_configs_native[] = {
> + { /* 19.2 MHz input clock */
> + .pll_pre_div_half = 1,
> + .pll_pre_div = 2,
> + .pll_mul = 75,
> + .m_div = 1,
> + .mipi_div = 3,
> + .pclk_div = 1,
> + .sys_pre_div = 1,
> + .sys_div = 2,
> + },
> + { /* 24MHz input clock */
> + .pll_pre_div_half = 1,
> + .pll_pre_div = 0,
> + .pll_mul = 30,
> + .m_div = 1,
> + .mipi_div = 3,
> + .pclk_div = 1,
> + .sys_pre_div = 1,
> + .sys_div = 2,
> + },

Could you instead add a struct specific to the clock frequency with
pointers to these? See e.g. the ov8856 driver how this could otherwise end
up...

> };
>
> /*
> - * EXTCLK = 24 MHz
> * DAC_CLK = 360 MHz
> * SCLK = 144 MHz
> */
>
> -static const struct ov8865_pll2_config ov8865_pll2_config_native = {
> - .pll_pre_div_half = 1,
> - .pll_pre_div = 0,
> - .pll_mul = 30,
> - .dac_div = 2,
> - .sys_pre_div = 5,
> - .sys_div = 0,
> +static const struct ov8865_pll2_config ov8865_pll2_configs_native[] = {
> + /* 19.2MHz input clock */
> + {
> + .pll_pre_div_half = 1,
> + .pll_pre_div = 5,
> + .pll_mul = 75,
> + .dac_div = 1,
> + .sys_pre_div = 1,
> + .sys_div = 3,
> + },
> + /* 24MHz input clock */
> + {
> + .pll_pre_div_half = 1,
> + .pll_pre_div = 0,
> + .pll_mul = 30,
> + .dac_div = 2,
> + .sys_pre_div = 5,
> + .sys_div = 0,
> + }
> };
>
> /*
> - * EXTCLK = 24 MHz
> * DAC_CLK = 360 MHz
> * SCLK = 72 MHz
> */
>
> -static const struct ov8865_pll2_config ov8865_pll2_config_binning = {
> +static const struct ov8865_pll2_config ov8865_pll2_configs_binning[] = {
> + /* 19.2MHz input clock */
> + {
> + .pll_pre_div_half = 1,
> + .pll_pre_div = 2,
> + .pll_mul = 75,
> + .dac_div = 2,
> + .sys_pre_div = 10,
> + .sys_div = 0,
> + },
> + /* 24MHz input clock */
> + {
> .pll_pre_div_half = 1,
> .pll_pre_div = 0,
> .pll_mul = 30,
> .dac_div = 2,
> .sys_pre_div = 10,
> .sys_div = 0,
> + }
> };
>
> static const struct ov8865_sclk_config ov8865_sclk_config_native = {
> @@ -934,8 +980,8 @@ static const struct ov8865_mode ov8865_modes[] = {
> .frame_interval = { 1, 30 },
>
> /* PLL */
> - .pll1_config = &ov8865_pll1_config_native,
> - .pll2_config = &ov8865_pll2_config_native,
> + .pll1_config = ov8865_pll1_configs_native,
> + .pll2_config = ov8865_pll2_configs_native,
> .sclk_config = &ov8865_sclk_config_native,
>
> /* Registers */
> @@ -990,8 +1036,8 @@ static const struct ov8865_mode ov8865_modes[] = {
> .frame_interval = { 1, 30 },
>
> /* PLL */
> - .pll1_config = &ov8865_pll1_config_native,
> - .pll2_config = &ov8865_pll2_config_native,
> + .pll1_config = ov8865_pll1_configs_native,
> + .pll2_config = ov8865_pll2_configs_native,
> .sclk_config = &ov8865_sclk_config_native,
>
> /* Registers */
> @@ -1050,8 +1096,8 @@ static const struct ov8865_mode ov8865_modes[] = {
> .frame_interval = { 1, 30 },
>
> /* PLL */
> - .pll1_config = &ov8865_pll1_config_native,
> - .pll2_config = &ov8865_pll2_config_binning,
> + .pll1_config = ov8865_pll1_configs_native,
> + .pll2_config = ov8865_pll2_configs_binning,
> .sclk_config = &ov8865_sclk_config_native,
>
> /* Registers */
> @@ -1116,8 +1162,8 @@ static const struct ov8865_mode ov8865_modes[] = {
> .frame_interval = { 1, 90 },
>
> /* PLL */
> - .pll1_config = &ov8865_pll1_config_native,
> - .pll2_config = &ov8865_pll2_config_binning,
> + .pll1_config = ov8865_pll1_configs_native,
> + .pll2_config = ov8865_pll2_configs_binning,
> .sclk_config = &ov8865_sclk_config_native,
>
> /* Registers */
> @@ -1513,12 +1559,11 @@ static int ov8865_isp_configure(struct ov8865_sensor *sensor)
> static unsigned long ov8865_mode_pll1_rate(struct ov8865_sensor *sensor,
> const struct ov8865_mode *mode)
> {
> - const struct ov8865_pll1_config *config = mode->pll1_config;
> - unsigned long extclk_rate;
> + const struct ov8865_pll1_config *config;
> unsigned long pll1_rate;
>
> - extclk_rate = clk_get_rate(sensor->extclk);
> - pll1_rate = extclk_rate * config->pll_mul / config->pll_pre_div_half;
> + config = &mode->pll1_config[sensor->extclk_rate_idx];
> + pll1_rate = sensor->extclk_rate * config->pll_mul / config->pll_pre_div_half;
>
> switch (config->pll_pre_div) {
> case 0:
> @@ -1552,10 +1597,12 @@ static int ov8865_mode_pll1_configure(struct ov8865_sensor *sensor,
> const struct ov8865_mode *mode,
> u32 mbus_code)
> {
> - const struct ov8865_pll1_config *config = mode->pll1_config;
> + const struct ov8865_pll1_config *config;
> u8 value;
> int ret;
>
> + config = &mode->pll1_config[sensor->extclk_rate_idx];
> +
> switch (mbus_code) {
> case MEDIA_BUS_FMT_SBGGR10_1X10:
> value = OV8865_MIPI_BIT_SEL(10);
> @@ -1622,9 +1669,11 @@ static int ov8865_mode_pll1_configure(struct ov8865_sensor *sensor,
> static int ov8865_mode_pll2_configure(struct ov8865_sensor *sensor,
> const struct ov8865_mode *mode)
> {
> - const struct ov8865_pll2_config *config = mode->pll2_config;
> + const struct ov8865_pll2_config *config;
> int ret;
>
> + config = &mode->pll2_config[sensor->extclk_rate_idx];
> +
> ret = ov8865_write(sensor, OV8865_PLL_CTRL12_REG,
> OV8865_PLL_CTRL12_PRE_DIV_HALF(config->pll_pre_div_half) |
> OV8865_PLL_CTRL12_DAC_DIV(config->dac_div));
> @@ -2053,9 +2102,11 @@ static int ov8865_mode_configure(struct ov8865_sensor *sensor,
> static unsigned long ov8865_mode_mipi_clk_rate(struct ov8865_sensor *sensor,
> const struct ov8865_mode *mode)
> {
> - const struct ov8865_pll1_config *config = mode->pll1_config;
> + const struct ov8865_pll1_config *config;
> unsigned long pll1_rate;
>
> + config = &mode->pll1_config[sensor->extclk_rate_idx];
> +
> pll1_rate = ov8865_mode_pll1_rate(sensor, mode);
>
> return pll1_rate / config->m_div / 2;
> @@ -2783,7 +2834,8 @@ static int ov8865_probe(struct i2c_client *client)
> struct ov8865_sensor *sensor;
> struct v4l2_subdev *subdev;
> struct media_pad *pad;
> - unsigned long rate;
> + unsigned int rate;
> + unsigned int i;
> int ret;
>
> sensor = devm_kzalloc(dev, sizeof(*sensor), GFP_KERNEL);
> @@ -2858,13 +2910,39 @@ static int ov8865_probe(struct i2c_client *client)
> goto error_endpoint;
> }
>
> - rate = clk_get_rate(sensor->extclk);
> - if (rate != OV8865_EXTCLK_RATE) {
> - dev_err(dev, "clock rate %lu Hz is unsupported\n", rate);
> + /*
> + * We could have either a 24MHz or 19.2MHz clock rate. Check for a
> + * clock-frequency property and if found, set that rate. This should
> + * cover ACPI case. If the system uses devicetree then the configured
> + * rate should already be set, so we'll have to check it.
> + */
> +
> + ret = fwnode_property_read_u32(dev_fwnode(dev), "clock-frequency",
> + &rate);
> + if (!ret) {
> + ret = clk_set_rate(sensor->extclk, rate);
> + if (ret) {
> + dev_err(dev, "failed to set clock rate\n");
> + return ret;
> + }
> + }
> +
> + sensor->extclk_rate = clk_get_rate(sensor->extclk);
> +
> + for (i = 0; i < ARRAY_SIZE(supported_extclk_rates); i++) {
> + if (sensor->extclk_rate == supported_extclk_rates[i])
> + break;
> + }
> +
> + if (i == ARRAY_SIZE(supported_extclk_rates)) {
> + dev_err(dev, "clock rate %lu Hz is unsupported\n",
> + sensor->extclk_rate);
> ret = -EINVAL;
> goto error_endpoint;
> }
>
> + sensor->extclk_rate_idx = i;
> +
> /* Subdev, entity and pad */
>
> subdev = &sensor->subdev;

--
Kind regards,

Sakari Ailus