Re: [Xen-devel] [PATCH] pl011: early_panic if baud rate not set in hardware

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 08/22/2013 05:01 PM, Ian Campbell wrote:
> Now that the driver defaults to BAUD_AUTO this can happen if the early uart !=
> console or if early printk isn't in use.

Does the fast model set correctly the baud rate?

> The following division by zero causes a trap but that uses regular printk and
> not early_printk, so it is never seen.

That's annoying. I often have this problem, is there any plan to support
early print in printk?

> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxxxxx>
> ---
>  xen/drivers/char/pl011.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
> 
> diff --git a/xen/drivers/char/pl011.c b/xen/drivers/char/pl011.c
> index 0e1eb64..7eb90b0 100644
> --- a/xen/drivers/char/pl011.c
> +++ b/xen/drivers/char/pl011.c
> @@ -104,6 +104,8 @@ static void __init pl011_init_preirq(struct serial_port 
> *port)
>      {
>          /* Baud rate already set: read it out from the divisor latch. */
>          divisor = (pl011_read(uart, IBRD) << 6) | (pl011_read(uart, FBRD));
> +        if (!divisor)
> +            early_panic("pl011: No Baud rate configured\n");
>          uart->baud = (uart->clock_hz << 2) / divisor;
>      }
>      /* This write must follow FBRD and IBRD writes. */
> 


-- 
Julien Grall

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