Re: [PATCHv4 2/3] tty/serial: at91: fix hardware handshake with GPIOs

From: Uwe Kleine-König
Date: Fri Sep 30 2016 - 05:12:48 EST

Hello Richard,

On Fri, Sep 30, 2016 at 10:58:00AM +0200, Richard Genoud wrote:
> Commit 1cf6e8fc8341 ("tty/serial: at91: fix RTS line management when
> hardware handshake is enabled") broke the hardware handshake when GPIOs
> were used.
> Hardware handshake with GPIOs used to work before this commit because
> the CRTSCTS flag (termios->c_cflag) was set, but not the
> ATMEL_US_USMODE_HWHS flag (controller register) ; so hardware handshake
> enabled, but not handled by the controller.

What does the HWHS flag control? What if only RTS is a gpio and CTS is
not? Or the other way round?

What is the problematic setup? I guess it's RTS and CTS are gpios and
with that setting ATMEL_US_USMODE_HWHS is wrong? What happens if that

Best regards

Pengutronix e.K. | Uwe Kleine-König |
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