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

Sakari Ailus
2021-08-10T21:49:27Z

On Tue, Aug 10, 2021 at 10:37:35PM +0100, Daniel Scally wrote:
> Hi Sakari - thanks for all the comments

You're welcome!

Nice patches btw.

>
> 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?

Yes, please --- ov8865_pll1_config_native above is thus the PLL
configuration for the 24 MHz clock.

--
Sakari Ailus