Date: Sun, 4 Jan 2009 12:16:52 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Tollef Fog Heen <tfheen@err.no>
Cc: linux-kernel@vger.kernel.org, werner@cornelius-consult.de,
       frank@kingswood-consulting.co.uk
Subject: Re: [PATCH] Winchiphead 340/1: full baud rate and status/control
 line support
Message-ID: <20090104121652.35a33c4c@lxorguk.ukuu.org.uk>
In-Reply-To: <87iqovs740.fsf@qurzaw.linpro.no>
References: <87iqovs740.fsf@qurzaw.linpro.no>
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> +	if (factor > 0xfff0) { /* Clamp */
> +		factor = 0xfff0;
> +		divisor = 0;
> +	}
> +
> +	t1 = factor;
> +	for (t2 = divisor; t2 <= CH341_BAUDBASE_DIVMAX; t2++)
> +		t1 >>= 3;
> +	baud = CH341_BAUDBASE_FACTOR / t1;
> +

Same question as before: Can baud really become zero at this point ? Also
for that matter what guarantees that t1 cannot become zero in this
computation ?


> +	if (baud && tty)
> +		tty_encode_baud_rate(tty, baud, baud);

The check for B0 (hangup) was done earlier (see set_termios). So if you
can end up with a requested baud rate being turned into 0 you need to
bump it up to 1. If not you don't need the test.

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