Messages in this thread | | | From | Richard Genoud <> | Date | Mon, 2 Jan 2017 15:14:37 +0100 | Subject | Re: [PATCH] tty/serial: atmel: RS485 half duplex w/DMA: enable RX after TX is done |
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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 ?
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