On Thu, May 02, 2024 at 12:02:46PM +0800, Weifeng Liu wrote:
> This is an attempt to alleviate race conditions in the SAM driver where
> essential resources like serial device and GPIO pins are not ready at
> the time ssam_serial_hub_probe() is called. Instead of giving up
> probing, a better way would be to defer the probing by returning
> -EPROBE_DEFER, allowing the kernel try again later.
>
> However, there is no way of identifying all such cases from other real
> errors in a few days. So let's take a gradual approach identify and
> address these cases as they arise. This commit marks the initial step
> in this process.
...
> + /* The following step can fail when it's called too early before the
> + * underlying uart device is ready (in this case -ENXIO is returned).
UART
> + * Instead of simply giving up and losing everything, we can defer
> + * the probing by returning -EPROBE_DEFER so that the kernel would be
> + * able to retry later. */
/*
* Use correct style for the comments.
* Here is the example.
*/
> status = serdev_device_open(serdev);
> - if (status)
> + if (status == -ENXIO)
> + status = -EPROBE_DEFER;
> + if (status) {
> + dev_err_probe(&serdev->dev, status,
> + "failed to open serdev device\n");
> goto err_devopen;
> + }
...
Hans, not sure if it helps, but we added similar into I²C and SPI code.
2dea645ffc21 ("i2c: acpi: Return error pointers from i2c_acpi_new_device()")
9c22ec4ac27b ("spi: Return deferred probe error when controller isn't yet available")
--
With Best Regards,
Andy Shevchenko
