linux-kernel - Re: [PATCH] serial: Two branches the same in timbuart_set

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Date:	Mon, 15 Mar 2010 14:41:46 +0100
From:	Richard Röjfors <richard.rojfors@...agicore.com>
To:	Roel Kluin <roel.kluin@...il.com>
Cc:	linux-serial@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH] serial: Two branches the same in timbuart_set_mctrl()

On 03/15/2010 02:33 PM, Roel Kluin wrote:
> Hi Richard,
>
>>>        if (mctrl&   TIOCM_RTS)
>>>            iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
>>>        else
>>> -        iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
>>> +        iowrite8(TIMBUART_CTRL_CTS, port->membase + TIMBUART_CTRL);
>>
>> This is not completely correct. CTS is a read only bit and we are to
>> stop signal RTS. So the line should look like:
>> iowrite8(0, port->membase + TIMBUART_CTRL);
>
> It appears as if this will also unset TIMBUART_CTRL_CTS (which is
> probably ok since it's read-only) but TIMBUART_CTRL_FLSHTX and
> TIMBUART_CTRL_FLSHRX as well.

TIMBUART_CTRL_FLSH(RX/TX) are write only bits, writing a 1 to these will
flush the corresponding FIFO. In this case we should not flush the FIFO:s,
so writing 0 as I suggested is correct.

>
> If not required I'll send the patch as you suggested.

Great! Thanks!

--Richard
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