Hello,
please temporary ignore this patch, as I've applied the same on
the twin RDACM21 driver and it doesn't actually help recovering
failures.
Sorry for the noise
On Tue, Jan 12, 2021 at 12:47:02PM +0100, Jacopo Mondi wrote:
> During the RDACM20 probe sequence the connected deserializer chip
> has to uses its I2C auto-acknowledgment feature as the reverse
> channel where I2C messages are transmitted on is not yet available.
>
> This makes it impossible to detect failures when communicating with
> the remote cameras, as all messages are acknowledged automatically.
>
> Reading the serializer chip id and verify it is correct is thus the
> only reliable way to make sure it has correctly started-up.
>
> The current implementation tries to read the chip id once, and bails
> out if it not correct, but does not give the serializer any time to
> exit from low power after the 'ping to wake-up' first transaction.
>
> Make the startup process more robust by:
> 1) Add a 5 milliseconds delay after the wake up message before
> starting the configuration procedure as suggested by the chip
> manual
> 2) Read the chip-id to make sure it has properly booted
> 3) Wrap the procedure in a for-loop and attempt configuration up
> to 10 times
>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
> ---
> drivers/media/i2c/rdacm20.c | 53 ++++++++++++++++++++++++-------------
> 1 file changed, 34 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/media/i2c/rdacm20.c b/drivers/media/i2c/rdacm20.c
> index 16bcb764b0e0..de4cb635eabe 100644
> --- a/drivers/media/i2c/rdacm20.c
> +++ b/drivers/media/i2c/rdacm20.c
> @@ -29,6 +29,8 @@
>
> #include "max9271.h"
>
> +#define MAX9271_RESET_CYCLES 10
> +
> #define OV10635_I2C_ADDRESS 0x30
>
> #define OV10635_SOFTWARE_RESET 0x0103
> @@ -453,35 +455,48 @@ static struct v4l2_subdev_ops rdacm20_subdev_ops = {
> static int rdacm20_initialize(struct rdacm20_device *dev)
> {
> unsigned int retry = 3;
> + unsigned int i;
> int ret;
>
> /* Verify communication with the MAX9271: ping to wakeup. */
> dev->serializer->client->addr = MAX9271_DEFAULT_ADDR;
> i2c_smbus_read_byte(dev->serializer->client);
>
> - /* Serial link disabled during config as it needs a valid pixel clock. */
> - ret = max9271_set_serial_link(dev->serializer, false);
> - if (ret)
> - return ret;
> + /* Configure MAX9271 and make sure we can read its ID. */
> + for (i = 0; i < MAX9271_RESET_CYCLES; ++i) {
> + usleep_range(5000, 8000);
>
> - /*
> - * Ensure that we have a good link configuration before attempting to
> - * identify the device.
> - */
> - max9271_configure_i2c(dev->serializer, MAX9271_I2CSLVSH_469NS_234NS |
> - MAX9271_I2CSLVTO_1024US |
> - MAX9271_I2CMSTBT_105KBPS);
> + /* Serial link disabled: it needs a valid pixel clock. */
> + ret = max9271_set_serial_link(dev->serializer, false);
> + if (ret)
> + return ret;
>
> - max9271_configure_gmsl_link(dev->serializer);
> + /*
> + * Ensure that we have a good link configuration before
> + * attempting to identify the device.
> + */
> + max9271_configure_i2c(dev->serializer,
> + MAX9271_I2CSLVSH_469NS_234NS |
> + MAX9271_I2CSLVTO_1024US |
> + MAX9271_I2CMSTBT_105KBPS);
> +
> + ret = max9271_configure_gmsl_link(dev->serializer);
> + if (ret)
> + return ret;
>
> - ret = max9271_verify_id(dev->serializer);
> - if (ret < 0)
> - return ret;
> + ret = max9271_set_address(dev->serializer, dev->addrs[0]);
> + if (ret < 0)
> + return ret;
> + dev->serializer->client->addr = dev->addrs[0];
>
> - ret = max9271_set_address(dev->serializer, dev->addrs[0]);
> - if (ret < 0)
> - return ret;
> - dev->serializer->client->addr = dev->addrs[0];
> + ret = max9271_verify_id(dev->serializer);
> + if (ret == 0)
> + break;
> + }
> + if (i == MAX9271_RESET_CYCLES) {
> + dev_err(dev->dev, "Failed to configure max9271");
> + return -ENODEV;
> + }
>
> /*
> * Reset the sensor by cycling the OV10635 reset signal connected to the
> --
> 2.29.2
>
