linux-kernel - Re: [patch 1/1] staging: speakup: flush tty buffers and ensure hardware flow control

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Date:   Thu, 11 May 2017 09:29:14 +0100
From:   Okash Khawaja <okash.khawaja@...il.com>
To:     Alan Cox <gnomes@...rguk.ukuu.org.uk>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Samuel Thibault <samuel.thibault@...-lyon.org>,
        linux-kernel@...r.kernel.org, William Hubbs <w.d.hubbs@...il.com>,
        Chris Brannon <chris@...-brannons.com>,
        Kirk Reiser <kirk@...sers.ca>, speakup@...ux-speakup.org,
        devel@...verdev.osuosl.org, John Covici <covici@....covici.com>
Subject: Re: [patch 1/1] staging: speakup: flush tty buffers and ensure
 hardware flow control

Hi Alan,

On Wed, May 10, 2017 at 08:41:51PM +0100, Alan Cox wrote:
> > +	if (!(tmp_termios.c_cflag & CRTSCTS)) {
> > +		tmp_termios.c_cflag |= CRTSCTS;
> > +		ret = tty_set_termios(tty, &tmp_termios);
> > +		if (ret)
> > +			pr_warn("speakup: Failed to set hardware flow control\n");
> 
> You should check the tty c_cflag after the call rather than rely on an
> error code. Strictly speaking tty_set_termios should error if no tty bits
> are changed by the request but it never has on Linux. Instead check the
> tty gave you the result you wanted.
Thanks. I will replace the check for return value with check for c_cflag.

May be we should fix this in tty_set_termios?