Hi Uli,
On Wed, Feb 8, 2017 at 11:04 AM, Ulrich Hecht
<[email protected]> wrote:
> On Tue, Feb 7, 2017 at 3:40 PM, Geert Uytterhoeven <[email protected]>
> wrote:
>> On Fri, Feb 3, 2017 at 11:38 AM, Ulrich Hecht
>> <[email protected]> wrote:
>>> Allows tuning of the RX FIFO fill threshold and timeout. (The latter is
>>> only applicable to SCIFA and SCIFB).
>>>
>>> Signed-off-by: Ulrich Hecht <[email protected]>
>>> Reviewed-by: Geert Uytterhoeven <[email protected]>
>>> ---
>>> drivers/tty/serial/sh-sci.c | 87
>>> +++++++++++++++++++++++++++++++++++++++++++++
>>> 1 file changed, 87 insertions(+)
>>>
>>> diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
>>> index 4a165ed..f95a56c 100644
>>> --- a/drivers/tty/serial/sh-sci.c
>>> +++ b/drivers/tty/serial/sh-sci.c
>>> @@ -1055,6 +1055,66 @@ static void rx_fifo_timer_fn(unsigned long arg)
>>> scif_set_rtrg(port, 1);
>>> }
>>>
>>> +static ssize_t rx_trigger_show(struct device *dev,
>>> + struct device_attribute *attr,
>>> + char *buf)
>>> +{
>>> + struct uart_port *port = dev_get_drvdata(dev);
>>> + struct sci_port *sci = to_sci_port(port);
>>> +
>>> + return sprintf(buf, "%d\n", sci->rx_trigger);
>>> +}
>>> +
>>> +static ssize_t rx_trigger_store(struct device *dev,
>>> + struct device_attribute *attr,
>>> + const char *buf,
>>> + size_t count)
>>> +{
>>> + struct uart_port *port = dev_get_drvdata(dev);
>>> + struct sci_port *sci = to_sci_port(port);
>>> + long r;
>>> +
>>> + if (kstrtol(buf, 0, &r) == -EINVAL)
>>> + return -EINVAL;
>>> + sci->rx_trigger = scif_set_rtrg(port, r);
>>> + scif_set_rtrg(port, 1);
>>
>> I seem to have missed the above function call during my earlier review.
>> What's the purpose of resetting the trigger immediately to 1?
>
> For the software timeout case, the timeout and the trigger levels are
> set in the interrupt handler. Setting the threshold to 1 will trigger
> that when the next byte of data comes in, and it is easier than
> duplicating the logic here.
OK.
> (There actually is a bug here, in that the threshold should only be
> reset to 1 for software timeout IPs (SCIFA and SCIFB), but that is not
> what breaks SCIFA, of course.)
I guess you'll send a patch to fix that, too?
>> I.e. "echo 1 > /sys/class/tty/ttySC0/device/rx_fifo_trigger" fixes serial
>> console input on e.g. armadillo, but echoing 32 into rx_fifo_trigger doesn't
>> break it again.
>
> This is intended to work that way. For software timeout devices (SCIFA
> and SCIFB), the trigger level is not set in hardware unless an
> rx_fifo_timeout > 0 is set as well.
>
> The bug that breaks the SCIFA console is in sci_reset(), which sets a
> hardware threshold > 1 for devices for software timeout devices even
> though the rx_fifo_timeout is 0. Something like this should fix it:
>
> --- a/drivers/tty/serial/sh-sci.c
> +++ b/drivers/tty/serial/sh-sci.c
> @@ -2179,7 +2179,11 @@ static void sci_reset(struct uart_port *port)
> setup_timer(&s->rx_fifo_timer, rx_fifo_timer_fn,
> (unsigned long)s);
> } else {
> - scif_set_rtrg(port, s->rx_trigger);
> + if (port->type == PORT_SCIFA ||
> + port->type == PORT_SCIFB)
> + scif_set_rtrg(port, 1);
> + else
> + scif_set_rtrg(port, s->rx_trigger);
> }
> }
> }
>
> Could you try and check if that works for you?
Thanks, that unbroke serial console input on all my boards with SCIFA consoles.
Tested-by: Geert Uytterhoeven <[email protected]>
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
