[U-Boot] [PATCH v2 09/11] drivers: serial_sifive: Skip baudrate config if no input clock

[Auer, Lukas]

Hi Anup,

On Fri, 2019-01-18 at 11:19 +0000, Anup Patel wrote:
> From: Atish Patra <atish.patra at wdc.com>
> 
> It is possible that input clock is not available because clk
> device was not available and 'clock-frequency' DT property is
> also not available.

Why would the clock device not be available?
I suspect the problem is that the clock driver is not probed pre-
relocation. Adding DM_FLAG_PRE_RELOC to the driver flags would fix
this.

> 
> In this case, instead of failing we should just skip baudrate
> config by returning zero.

Won't this cause issues if an incorrect baudrate is set?

Thanks,
Lukas

> 
> Signed-off-by: Atish Patra <atish.patra at wdc.com>
> Signed-off-by: Anup Patel <anup.patel at wdc.com>
> Reviewed-by: Alexander Graf <agraf at suse.de>
> ---
>  drivers/serial/serial_sifive.c | 32 ++++++++++++++++----------------
>  1 file changed, 16 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/serial/serial_sifive.c
> b/drivers/serial/serial_sifive.c
> index ea4d35d48c..537bc7a975 100644
> --- a/drivers/serial/serial_sifive.c
> +++ b/drivers/serial/serial_sifive.c
> @@ -99,27 +99,27 @@ static int _sifive_serial_getc(struct uart_sifive
> *regs)
>  
>  static int sifive_serial_setbrg(struct udevice *dev, int baudrate)
>  {
> -	int err;
> +	int ret;
>  	struct clk clk;
>  	struct sifive_uart_platdata *platdata = dev_get_platdata(dev);
> +	u32 clock = 0;
>  
> -	err = clk_get_by_index(dev, 0, &clk);
> -	if (!err) {
> -		err = clk_get_rate(&clk);
> -		if (!IS_ERR_VALUE(err))
> -			platdata->clock = err;
> -	} else if (err != -ENOENT && err != -ENODEV && err != -ENOSYS)
> {
> +	ret = clk_get_by_index(dev, 0, &clk);
> +	if (IS_ERR_VALUE(ret)) {
>  		debug("SiFive UART failed to get clock\n");
> -		return err;
> -	}
> -
> -	if (!platdata->clock)
> -		platdata->clock = dev_read_u32_default(dev, "clock-
> frequency", 0);
> -	if (!platdata->clock) {
> -		debug("SiFive UART clock not defined\n");
> -		return -EINVAL;
> +		ret = dev_read_u32(dev, "clock-frequency", &clock);
> +		if (IS_ERR_VALUE(ret)) {
> +			debug("SiFive UART clock not defined\n");
> +			return 0;
> +		}
> +	} else {
> +		clock = clk_get_rate(&clk);
> +		if (IS_ERR_VALUE(clock)) {
> +			debug("SiFive UART clock get rate failed\n");
> +			return 0;
> +		}
>  	}
> -
> +	platdata->clock = clock;
>  	_sifive_serial_setbrg(platdata->regs, platdata->clock,
> baudrate);
>  
>  	return 0;