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SubjectRe: Linux 3.15: SPARC serial console regression
Hi,

On Mon, Jun 09, 2014 at 07:48:17PM -0400, Peter Hurley wrote:
> Looks like Seth's fix exposes some broken assumptions in the Sun
> serial drivers.

Thanks, that seems to fix the issue.

Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi>

> PS - Do you have a way to test also your setup using hardware flow
> control, ie. CRTSCTS? I ask because I would expect that to be broken
> even before Seth's patch.

Sorry, I'm unable do that at the moment.

A.

> --- %< ---
> From: Peter Hurley <peter@hurleysoftware.com>
> Date: Mon, 9 Jun 2014 19:21:43 -0400
> Subject: [PATCH] serial: sunsab: Test for no tx data on tx restart
>
> Commit 717f3bbab3c7628736ef738fdbf3d9a28578c26c,
> 'serial_core: Fix conditional start_tx on ring buffer not empty'
> exposes an incorrect assumption in sunsab's start_tx method; the
> tx ring buffer can, in fact, be empty when restarting tx when
> performing flow control.
>
> Test for empty tx ring buffer when in sunsab's start_tx method.
>
> Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
> ---
> drivers/tty/serial/sunsab.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/tty/serial/sunsab.c b/drivers/tty/serial/sunsab.c
> index 5faa8e9..b99a4ea 100644
> --- a/drivers/tty/serial/sunsab.c
> +++ b/drivers/tty/serial/sunsab.c
> @@ -427,6 +427,9 @@ static void sunsab_start_tx(struct uart_port *port)
> struct circ_buf *xmit = &up->port.state->xmit;
> int i;
>
> + if (uart_circ_empty(xmit))
> + return;
> +
> up->interrupt_mask1 &= ~(SAB82532_IMR1_ALLS|SAB82532_IMR1_XPR);
> writeb(up->interrupt_mask1, &up->regs->w.imr1);
>
> --
> 2.0.0
>
> --
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