Hi Jai On Mon, Dec 19, 2022 at 08:00:54PM +0530, Jai Luthra wrote: > Some module manufacturers [1][2] don't expose the RESETB and PWDN pins > of the sensor directly through the 15-pin FFC connector. Instead wiring > ~PWDN gpio to the sensor pins with appropriate delays. > > In such cases, reset_gpio will not be available to the driver, but it > will still be toggled when the sensor is powered on, and thus we should > still honor the wait time of >= 5ms + 1ms + 20ms (see figure 2-3 in [3]) > before attempting any i/o operations over SCCB. > > Also, rename the function to ov5640_powerup_sequence to better match the > datasheet (section 2.7). > > [1] https://digilent.com/reference/_media/reference/add-ons/pcam-5c/pcam_5c_sch.pdf > [2] https://www.alinx.com/public/upload/file/AN5641_User_Manual.pdf > [3] https://cdn.sparkfun.com/datasheets/Sensors/LightImaging/OV5640_datasheet.pdf > > Fixes: 19a81c1426c1 ("[media] add Omnivision OV5640 sensor driver") > Signed-off-by: Jai Luthra <j-luthra@xxxxxx> This looks fine to me Reviewed-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx> Thanks j > --- > drivers/media/i2c/ov5640.c | 22 ++++++++++++++++------ > 1 file changed, 16 insertions(+), 6 deletions(-) > > diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c > index a9cd21c49147..41e4a4f1b99d 100644 > --- a/drivers/media/i2c/ov5640.c > +++ b/drivers/media/i2c/ov5640.c > @@ -2372,11 +2372,22 @@ static void ov5640_power(struct ov5640_dev *sensor, bool enable) > gpiod_set_value_cansleep(sensor->pwdn_gpio, enable ? 0 : 1); > } > > -static void ov5640_reset(struct ov5640_dev *sensor) > +/* > + * From section 2.7 power up sequence: > + * t0 + t1 + t2 >= 5ms Delay from DOVDD stable to PWDN pull down > + * t3 >= 1ms Delay from PWDN pull down to RESETB pull up > + * t4 >= 20ms Delay from RESETB pull up to SCCB (i2c) stable > + * > + * Some modules don't expose RESETB/PWDN pins directly, instead providing a > + * "PWUP" GPIO which is wired through appropriate delays and inverters to the > + * pins. > + * > + * In such cases, this gpio should be mapped to pwdn_gpio in the driver, and we > + * should still toggle the pwdn_gpio below with the appropriate delays, while > + * the calls to reset_gpio will be ignored. > + */ > +static void ov5640_powerup_sequence(struct ov5640_dev *sensor) > { > - if (!sensor->reset_gpio) > - return; > - > gpiod_set_value_cansleep(sensor->reset_gpio, 0); > > /* camera power cycle */ > @@ -2412,8 +2423,7 @@ static int ov5640_set_power_on(struct ov5640_dev *sensor) > goto xclk_off; > } > > - ov5640_reset(sensor); > - ov5640_power(sensor, true); > + ov5640_powerup_sequence(sensor); > > ret = ov5640_init_slave_id(sensor); > if (ret) > -- > 2.17.1 >
