Hi Jacopo,
Thank you for the patch.
On Mon, Mar 15, 2021 at 02:15:05PM +0100, Jacopo Mondi wrote:
> The OV10640 image sensor powerdown signal is controlled by the first
> line of the OV490 GPIO pad #1, but the pad #0 identifier
> OV490_GPIO_OUTPUT_VALUE0 was erroneously used. As a result the image
> sensor powerdown signal was never asserted but was kept high by an
> internal pull-up resistor, causing sporadic failures during the
> image sensor startup phase.
>
> Fix this by using the correct GPIO pad identifier.
>
> While at it also fix the GPIO signal handling sequence, as the reset
> line was released before the powerdown one, and introduce the correct
> delays in between the two operations.
>
> Wait the mandatory 1 millisecond delay after the powerup lane is
> asserted. The reset delay is not characterized in the chip manual if
> not as "255 XVCLK + initialization". Wait for at least 3 milliseconds
> to guarantee the SCCB bus is available.
>
> This commit fixes a sporadic start-up error triggered by a failure to
> read the OV10640 chip ID:
> rdacm21 8-0054: OV10640 ID mismatch: (0x01)
>
> Fixes: a59f853b3b4b ("media: i2c: Add driver for RDACM21 camera module")
> Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> ---
> drivers/media/i2c/rdacm21.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/i2c/rdacm21.c b/drivers/media/i2c/rdacm21.c
> index 7bce55adfd7c..50a9b0d8255d 100644
> --- a/drivers/media/i2c/rdacm21.c
> +++ b/drivers/media/i2c/rdacm21.c
> @@ -333,13 +333,15 @@ static int ov10640_initialize(struct rdacm21_device *dev)
> {
> u8 val;
>
> - /* Power-up OV10640 by setting RESETB and PWDNB pins high. */
> + /* Power-up OV10640 by setting PWDNB and RESETB pins high. */
> ov490_write_reg(dev, OV490_GPIO_SEL0, OV490_GPIO0);
> ov490_write_reg(dev, OV490_GPIO_SEL1, OV490_SPWDN0);
> ov490_write_reg(dev, OV490_GPIO_DIRECTION0, OV490_GPIO0);
> ov490_write_reg(dev, OV490_GPIO_DIRECTION1, OV490_SPWDN0);
> +
> + ov490_write_reg(dev, OV490_GPIO_OUTPUT_VALUE1, OV490_SPWDN0);
> + usleep_range(1500, 3000);
> ov490_write_reg(dev, OV490_GPIO_OUTPUT_VALUE0, OV490_GPIO0);
> - ov490_write_reg(dev, OV490_GPIO_OUTPUT_VALUE0, OV490_SPWDN0);
> usleep_range(3000, 5000);
>
> /* Read OV10640 ID to test communications. */
--
Regards,
Laurent Pinchart
