Hi Jacopo,
Thank you for the patch.
On Mon, Mar 15, 2021 at 02:15:03PM +0100, Jacopo Mondi wrote:
> The MAX9271 chip manual prescribes a delay of 5 milliseconds
> after the chip exists from low power state.
I don't think we'll ever try to access the chip within 5ms of the
beginning of its existence.
s/exists/exits/
:-)
> Add a new function to the max9271 library driver that wakes up the chip
> with a dummy i2c transaction and implements the correct delay of 5
> milliseconds after the chip exits from low power state.
>
> Use the newly introduced function in the rdacm20 and rdacm21 camera
> drivers. The former was not respecting the required delay while the
> latter was waiting for a too-short timeout.
>
> Do not handle the initial i2c address configuration in the library
> driver function as the camera module drivers control address
> reprogramming.
Isn't the initial address fixed though ? Nonetheless, this can be
addressed separately, so
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> ---
> drivers/media/i2c/max9271.c | 7 +++++++
> drivers/media/i2c/max9271.h | 9 +++++++++
> drivers/media/i2c/rdacm20.c | 2 +-
> drivers/media/i2c/rdacm21.c | 3 +--
> 4 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/i2c/max9271.c b/drivers/media/i2c/max9271.c
> index 2c7dc7fb9846..f7bfe7266763 100644
> --- a/drivers/media/i2c/max9271.c
> +++ b/drivers/media/i2c/max9271.c
> @@ -80,6 +80,13 @@ static int max9271_pclk_detect(struct max9271_device *dev)
> return -EIO;
> }
>
> +void max9271_wake_up(struct max9271_device *dev)
> +{
> + i2c_smbus_read_byte(dev->client);
> + usleep_range(5000, 8000);
> +}
> +EXPORT_SYMBOL_GPL(max9271_wake_up);
> +
> int max9271_set_serial_link(struct max9271_device *dev, bool enable)
> {
> int ret;
> diff --git a/drivers/media/i2c/max9271.h b/drivers/media/i2c/max9271.h
> index d78fb21441e9..dc5e4e70ba6f 100644
> --- a/drivers/media/i2c/max9271.h
> +++ b/drivers/media/i2c/max9271.h
> @@ -85,6 +85,15 @@ struct max9271_device {
> struct i2c_client *client;
> };
>
> +/**
> + * max9271_wake_up() - Wake up the serializer by issuing an i2c transaction
> + * @dev: The max9271 device
> + *
> + * This function shall be called before any other interaction with the
> + * serializer.
> + */
> +void max9271_wake_up(struct max9271_device *dev);
> +
> /**
> * max9271_set_serial_link() - Enable/disable serial link
> * @dev: The max9271 device
> diff --git a/drivers/media/i2c/rdacm20.c b/drivers/media/i2c/rdacm20.c
> index b9aaa0f7db42..2265ef7c65d4 100644
> --- a/drivers/media/i2c/rdacm20.c
> +++ b/drivers/media/i2c/rdacm20.c
> @@ -459,7 +459,7 @@ static int rdacm20_initialize(struct rdacm20_device *dev)
>
> /* Verify communication with the MAX9271: ping to wakeup. */
> dev->serializer.client->addr = MAX9271_DEFAULT_ADDR;
> - i2c_smbus_read_byte(dev->serializer.client);
> + max9271_wake_up(&dev->serializer);
>
> /* Serial link disabled during config as it needs a valid pixel clock. */
> ret = max9271_set_serial_link(&dev->serializer, false);
> diff --git a/drivers/media/i2c/rdacm21.c b/drivers/media/i2c/rdacm21.c
> index 179d107f494c..7bce55adfd7c 100644
> --- a/drivers/media/i2c/rdacm21.c
> +++ b/drivers/media/i2c/rdacm21.c
> @@ -452,8 +452,7 @@ static int rdacm21_initialize(struct rdacm21_device *dev)
>
> /* Verify communication with the MAX9271: ping to wakeup. */
> dev->serializer.client->addr = MAX9271_DEFAULT_ADDR;
> - i2c_smbus_read_byte(dev->serializer.client);
> - usleep_range(3000, 5000);
> + max9271_wake_up(&dev->serializer);
>
> /* Enable reverse channel and disable the serial link. */
> ret = max9271_set_serial_link(&dev->serializer, false);
--
Regards,
Laurent Pinchart
