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tty/serial: atmel: fix RS485 half duplex with DMA

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When using DMA, half duplex doesn't work properly because rx is not stopped
before starting tx. Ensure we call atmel_stop_rx() in the DMA case.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexandre Belloni 2016-05-28 00:54:08 +02:00 • committed by Greg Kroah-Hartman
parent 637ba54f60
commit 0058f0871e
1 changed files with 8 additions and 6 deletions
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8
drivers/tty/serial/atmel_serial.c
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@ -487,19 +487,21 @@ static void atmel_start_tx(struct uart_port *port)
{ {
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
if (atmel_use_pdc_tx(port)) { if (atmel_use_pdc_tx(port) && (atmel_uart_readl(port, ATMEL_PDC_PTSR)
if (atmel_uart_readl(port, ATMEL_PDC_PTSR) & ATMEL_PDC_TXTEN) & ATMEL_PDC_TXTEN))
/* The transmitter is already running. Yes, we /* The transmitter is already running. Yes, we
really need this.*/ really need this.*/
return; return;
if (atmel_use_pdc_tx(port) || atmel_use_dma_tx(port))
if ((port->rs485.flags & SER_RS485_ENABLED) && if ((port->rs485.flags & SER_RS485_ENABLED) &&
!(port->rs485.flags & SER_RS485_RX_DURING_TX)) !(port->rs485.flags & SER_RS485_RX_DURING_TX))
atmel_stop_rx(port); atmel_stop_rx(port);
if (atmel_use_pdc_tx(port))
/* re-enable PDC transmit */ /* re-enable PDC transmit */
atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTEN); atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTEN);
}
/* Enable interrupts */ /* Enable interrupts */
atmel_uart_writel(port, ATMEL_US_IER, atmel_port->tx_done_mask); atmel_uart_writel(port, ATMEL_US_IER, atmel_port->tx_done_mask);
} }