From: Greg KH <gregkh@linuxfoundation.org>
To: Richard Genoud <richard.genoud@gmail.com>
Cc: Gil Weber <webergil@gmail.com>,
Nicolas Ferre <nicolas.ferre@atmel.com>,
"linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"#4 . 4+" <stable@vger.kernel.org>,
Alexandre Belloni <alexandre.belloni@free-electrons.com>
Subject: Re: [PATCH] tty/serial: atmel: RS485 half duplex w/DMA: enable RX after TX is done
Date: Wed, 11 Jan 2017 08:09:09 +0100 [thread overview]
Message-ID: <20170111070909.GA24787@kroah.com> (raw)
In-Reply-To: <CACQ1gAifm3nWOyfGbugHf4pFDQ7NCks+H+cjZcwEhjPqfJ=5Mw@mail.gmail.com>
On Mon, Jan 02, 2017 at 03:14:37PM +0100, Richard Genoud wrote:
> 2017-01-02 12:53 GMT+01:00 Alexandre Belloni
> <alexandre.belloni@free-electrons.com>:
> > On 06/12/2016 at 13:05:33 +0100, Richard Genoud wrote :
> >> When using RS485 in half duplex, RX should be enabled when TX is
> >> finished, and stopped when TX starts.
> >>
> >> Before commit 0058f0871efe7b01c6 ("tty/serial: atmel: fix RS485 half
> >> duplex with DMA"), RX was not disabled in atmel_start_tx() if the DMA
> >> was used. So, collisions could happened.
> >>
> >> But disabling RX in atmel_start_tx() uncovered another bug:
> >> RX was enabled again in the wrong place (in atmel_tx_dma) instead of
> >> being enabled when TX is finished (in atmel_complete_tx_dma), so the
> >> transmission simply stopped.
> >>
> >> This bug was not triggered before commit 0058f0871efe7b01c6
> >> ("tty/serial: atmel: fix RS485 half duplex with DMA") because RX was
> >> never disabled before.
> >>
> >> Moving atmel_start_rx() in atmel_complete_tx_dma() corrects the problem.
> >>
> >> Cc: stable@vger.kernel.org
> >> Reported-by: Gil Weber <webergil@gmail.com>
> >> Tested-by: Gil Weber <webergil@gmail.com>
> >> Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
> >
> > Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> >
> Greg, could you take this patch in your tree ?
Yes, will do so, thanks.
greg k-h
prev parent reply other threads:[~2017-01-11 7:09 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-06 12:05 [PATCH] tty/serial: atmel: RS485 half duplex w/DMA: enable RX after TX is done Richard Genoud
2017-01-02 11:53 ` Alexandre Belloni
2017-01-02 14:14 ` Richard Genoud
2017-01-11 7:09 ` Greg KH [this message]
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