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

Daniel Scally
2021-08-10T21:38:01Z

Hi Sakari - thanks for all the comments

On 10/08/2021 14:34, Sakari Ailus wrote:
> 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...

You mean something like

static struct ov8865_pll_configs_19_2_mhz {

.pll1_config_native = &ov8865_pll1_config_native,

...

};

static struct ov8865_pll_configs_24_mhz {

.pll1_config_native = &ov8865_pll1_config_native,

...

};

or am I misunderstanding?

>
>> };
>>
>> /*
>> - * 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;