Hi Jacopo, Thank you for the comments. On 29/12/22 23:37, Jacopo Mondi wrote:
Hi Jai On Tue, Dec 27, 2022 at 11:06:33PM +0530, Jai Luthra wrote:Move the register-based reset out of the init_setting[] and into the powerup_sequence function. The sensor is power cycled and reset using the gpio pins so the soft reset is not always necessary. This also ensures that soft reset honors the timing sequence from the datasheet [1]. [1] https://cdn.sparkfun.com/datasheets/Sensors/LightImaging/OV5640_datasheet.pdf Fixes: 19a81c1426c1 ("[media] add Omnivision OV5640 sensor driver") Suggested-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx> Signed-off-by: Jai Luthra <j-luthra@xxxxxx> --- drivers/media/i2c/ov5640.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c index e6525caa9b8c..5df16fb6f0a0 100644 --- a/drivers/media/i2c/ov5640.c +++ b/drivers/media/i2c/ov5640.c @@ -50,6 +50,7 @@ #define OV5640_REG_SYS_CTRL0 0x3008 #define OV5640_REG_SYS_CTRL0_SW_PWDN 0x42 #define OV5640_REG_SYS_CTRL0_SW_PWUP 0x02 +#define OV5640_REG_SYS_CTRL0_SW_RST 0x82 #define OV5640_REG_CHIP_ID 0x300a #define OV5640_REG_IO_MIPI_CTRL00 0x300e #define OV5640_REG_PAD_OUTPUT_ENABLE01 0x3017 @@ -532,7 +533,7 @@ static const struct v4l2_mbus_framefmt ov5640_default_fmt = { }; static const struct reg_value ov5640_init_setting[] = { - {0x3103, 0x11, 0, 0}, {0x3008, 0x82, 0, 5}, {0x3008, 0x42, 0, 0}, + {0x3103, 0x11, 0, 0}, {0x3008, 0x42, 0, 0},have you tried removing the second entry {0x3008, 0x42, 0, 0}, as well ? The SW_PWDN state allows programming registers (how can you exit with SW_PWUP otherwise?), so it's probably right to have it there.
Yes, I initially removed it from here and kept it in the powerup_sequence() but logic to set SW_PWDN became in that function became a bit complicated:
When we are using HW pins, we want to wait 20ms after de-asserting RESET before doing any SCCB register writes. But when we are using SW reset, we were using this register write to de-assert RESET, and then wait 20ms.
I found it cleaner to just keep it here where the registers are being programmed for both the cases. But I don't have a strong opinion either way.
{0x3103, 0x03, 0, 0}, {0x3630, 0x36, 0, 0}, {0x3631, 0x0e, 0, 0}, {0x3632, 0xe2, 0, 0}, {0x3633, 0x12, 0, 0}, {0x3621, 0xe0, 0, 0}, {0x3704, 0xa0, 0, 0}, {0x3703, 0x5a, 0, 0}, @@ -2440,18 +2441,27 @@ static void ov5640_power(struct ov5640_dev *sensor, bool enable) */ static void ov5640_powerup_sequence(struct ov5640_dev *sensor) { - gpiod_set_value_cansleep(sensor->reset_gpio, 0); + if (sensor->pwdn_gpio) { + gpiod_set_value_cansleep(sensor->reset_gpio, 0); - /* camera power cycle */ - ov5640_power(sensor, false); - usleep_range(5000, 10000); - ov5640_power(sensor, true); - usleep_range(5000, 10000); + /* camera power cycle */ + ov5640_power(sensor, false); + usleep_range(5000, 10000); + ov5640_power(sensor, true); + usleep_range(5000, 10000); - gpiod_set_value_cansleep(sensor->reset_gpio, 1); - usleep_range(1000, 2000); + gpiod_set_value_cansleep(sensor->reset_gpio, 1); + usleep_range(1000, 2000); - gpiod_set_value_cansleep(sensor->reset_gpio, 0); + gpiod_set_value_cansleep(sensor->reset_gpio, 0); + } else { + /* software reset */ + ov5640_write_reg(sensor, OV5640_REG_SYS_CTRL0, + OV5640_REG_SYS_CTRL0_SW_RST); + usleep_range(5000, 10000); + ov5640_write_reg(sensor, OV5640_REG_SYS_CTRL0, + OV5640_REG_SYS_CTRL0_SW_PWUP);But now I wonder if this last PWUP is necessary, since init_settings[] (which programs PWDN) is programmed immediately after.
Using the PWUP (0x02) as a way to de-assert RST (0x42) here, and not as an actual PWUP per se.
+ } usleep_range(20000, 25000);
Now that I think of it, we can move the PWDN from the register table to here, after this sleep - and keep the (0x02) above to de-assert reset. Let me know your thoughts.
} -- 2.17.1
Thanks, Jai
