[U-Boot] [PATCH 1/7] serial: Use next serial device if probing fails

[Heinrich Schuchardt]

On 01/16/2018 02:47 PM, Alexander Graf wrote:
> Currently our serial device search chokes on the fact that the serial
> probe function could fail. If it does, instead of searching for the next
> usable serial device, it just quits.
> 
> This patch changes the fallback logic so that even when a serial device
> was not probed correctly, we just try the next ones until we find one that
> works.
> 
> Signed-off-by: Alexander Graf <agraf at suse.de>
> ---
>  drivers/serial/serial-uclass.c | 23 +++++++++++++++++++----
>  1 file changed, 19 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/serial/serial-uclass.c b/drivers/serial/serial-uclass.c
> index 2e5116f7ce..637544d1a7 100644
> --- a/drivers/serial/serial-uclass.c
> +++ b/drivers/serial/serial-uclass.c
> @@ -74,6 +74,7 @@ static void serial_find_console_or_panic(void)
>  {
>  	const void *blob = gd->fdt_blob;
>  	struct udevice *dev;
> +	int ret;
>  
>  	if (CONFIG_IS_ENABLED(OF_PLATDATA)) {
>  		uclass_first_device(UCLASS_SERIAL, &dev);
> @@ -104,8 +105,8 @@ static void serial_find_console_or_panic(void)
>  		 * from 1!).
>  		 *
>  		 * Failing that, get the device with sequence number 0, or in
> -		 * extremis just the first serial device we can find. But we
> -		 * insist on having a console (even if it is silent).
> +		 * extremis just the first working serial device we can find.
> +		 * But we insist on having a console (even if it is silent).
>  		 */
>  #ifdef CONFIG_CONS_INDEX
>  #define INDEX (CONFIG_CONS_INDEX - 1)
> @@ -113,8 +114,22 @@ static void serial_find_console_or_panic(void)
>  #define INDEX 0
>  #endif

Why would you try probing by INDEX if CONFIG_CONS_INDEX is not defined?
You could place the else before /* Search for any working device */.

>  		if (!uclass_get_device_by_seq(UCLASS_SERIAL, INDEX, &dev) ||
> -		    !uclass_get_device(UCLASS_SERIAL, INDEX, &dev) ||
> -		    (!uclass_first_device(UCLASS_SERIAL, &dev) && dev)) {
> +		    !uclass_get_device(UCLASS_SERIAL, INDEX, &dev)) {
> +			if (dev->flags & DM_FLAG_ACTIVATED) {
> +				gd->cur_serial_dev = dev;
> +				return;
> +			}
> +		}
> +
> +		/* Search for any working device */
> +		for (ret = uclass_first_device_check(UCLASS_SERIAL, &dev);
> +		     dev;
> +		     ret = uclass_next_device_check(&dev)) {
> +			if (ret) {
> +				/* Device did succeed probing */

Above you wrote that you want the first and not the last device.

If this line is reached upon success, wouldn't you set
gd->cur_serial_dev here and return?

Best regards

Heinrich

> +				continue;
> +			}
> +
>  			gd->cur_serial_dev = dev;
>  			return;
>  		}
>