Hi Laurent,
On Fri, Jan 6, 2017 at 1:30 PM, Laurent Pinchart
<laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
> On Friday 02 Dec 2016 13:35:10 Geert Uytterhoeven wrote:
>> If a UART has dedicated RTS/CTS pins, there are some issues:
>> 1. When changing hardware control flow, the new AUTORTS state is not
>> immediately reflected in the hardware, but only when RTS is raised.
>> However, the serial core doesn't call .set_mctrl() after
>> .set_termios(), hence AUTORTS may only become effective when the port
>> is closed, and reopened later.
>> Note that this problem does not happen when manually using stty to
>> change CRTSCTS, as AUTORTS will work fine on next open.
>>
>> 2. When hardware control flow is disabled (or AUTORTS is not yet
>> effective), changing any serial port configuration deasserts RTS, as
>> .set_termios() calls sci_init_pins().
>
> Isn't this still a problem with this patch applied ? Calling sci_set_mctrl()
> should reconfigure the pins properly, but won't there be a short window during
> which the configuration will be wrong ?
You mean in between the calls to sci_init_pins() and sci_set_mctrl()?
I don't think _de_asserting RTS for a few microseconds matters much, would it?
Asserting RTS wrongly would be worse.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
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
