On Wed, Oct 17, 2018 at 09:37:17PM +0200, Jacopo Mondi wrote:
> Check that the PLL1 output frequency does not exceed the maximum allowed 1GHz
> frequency.
>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> ---
> drivers/media/i2c/ov5640.c | 23 +++++++++++++++++++----
> 1 file changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
> index e098435..1f2e72d 100644
> --- a/drivers/media/i2c/ov5640.c
> +++ b/drivers/media/i2c/ov5640.c
> @@ -770,7 +770,7 @@ static int ov5640_mod_reg(struct ov5640_dev *sensor, u16 reg,
> * always set to either 1 or 2 in the vendor kernels.
> */
> #define OV5640_SYSDIV_MIN 1
> -#define OV5640_SYSDIV_MAX 2
> +#define OV5640_SYSDIV_MAX 16
>
> /*
> * This is supposed to be ranging from 1 to 16, but the value is always
> @@ -806,15 +806,20 @@ static int ov5640_mod_reg(struct ov5640_dev *sensor, u16 reg,
> * This is supposed to be ranging from 1 to 8, but the value is always
> * set to 1 in the vendor kernels.
> */
> -#define OV5640_PCLK_ROOT_DIV 1
> +#define OV5640_PCLK_ROOT_DIV 1
> +#define OV5640_PLL_SYS_ROOT_DIVIDER_BYPASS 0x00
>
> static unsigned long ov5640_compute_sys_clk(struct ov5640_dev *sensor,
> u8 pll_prediv, u8 pll_mult,
> u8 sysdiv)
> {
> - unsigned long rate = clk_get_rate(sensor->xclk);
> + unsigned long sysclk = sensor->xclk_freq / pll_prediv * pll_mult;
>
> - return rate / pll_prediv * pll_mult / sysdiv;
> + /* PLL1 output cannot exceed 1GHz. */
> + if (sysclk / 1000000 > 1000)
> + return 0;
> +
> + return sysclk / sysdiv;
> }
>
> static unsigned long ov5640_calc_sys_clk(struct ov5640_dev *sensor,
> @@ -844,6 +849,16 @@ static unsigned long ov5640_calc_sys_clk(struct ov5640_dev *sensor,
> _rate = ov5640_compute_sys_clk(sensor,
> OV5640_PLL_PREDIV,
> _pll_mult, _sysdiv);
> +
> + /*
> + * We have reached the maximum allowed PLL1 output,
> + * increase sysdiv.
> + */
> + if (rate == 0) {
> + _pll_mult = OV5640_PLL_MULT_MAX + 1;
> + continue;
> + }
> +
Both your patches look sane to me. However, I guess here you're
setting _pll_mult at this value so that you won't reach the for
condition on the next iteration?
Wouldn't it be cleaner to just use a break statement here?
Thanks!
Maxime
--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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