Hello Greg,
On Thu, Mar 01, 2018 at 09:35:38PM +0100, Uwe Kleine-König wrote:
> On an i.MX6Q based system using the imx-UART in rs485 mode the following
> could be observed: When a character is supposed to be sent,
> imx_start_tx() enables the Transmit Complete Interrupt (UCR4_TCEN) and
> then enables DMA. If then the Transmit Complete Interrupt triggers
> before the DMA request starts to send characters the irq handler
> disables the Transmitter Empty Interrupt (UCR1_TXMPTYEN) in
> imx_transmit_buffer() but not Transmit Complete Interrupt and so fails
> to remove this irq source which prevents the DMA request to start and
> completely locks up the system.
>
> To prevent this lock-up also disable UCR4_TCEN when starting DMA and
> expand the comment accordingly.
>
> Fixes: 17b8f2a3fdca ("serial: imx: add support for half duplex rs485")
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
With v4 of the imx-serial clean up series I'm about to send, this patch
is obsolete. So it's safe to delete it from your mailbox.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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