From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH 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 Message-ID: <20170111070909.GA24787@kroah.com> References: <20161206120533.14505-1-richard.genoud@gmail.com> <20170102115326.mfly6w5k3dllfpur@piout.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Richard Genoud Cc: Gil Weber , Nicolas Ferre , "linux-serial@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "#4 . 4+" , Alexandre Belloni List-Id: linux-serial@vger.kernel.org On Mon, Jan 02, 2017 at 03:14:37PM +0100, Richard Genoud wrote: > 2017-01-02 12:53 GMT+01:00 Alexandre Belloni > : > > 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 > >> Tested-by: Gil Weber > >> Signed-off-by: Richard Genoud > > > > Acked-by: Alexandre Belloni > > > Greg, could you take this patch in your tree ? Yes, will do so, thanks. greg k-h