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| author | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2018-03-02 11:07:28 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-06-20 10:24:58 +0200 |
| commit | fcc388ca888e1100507ff6f961b4175826f83c84 (patch) | |
| tree | bde8a7135a1d05139d319448496ff7e543f1d35c /drivers/tty | |
| parent | f7ce58abbe9b4e7d6ace23f593235dd1a8177b59 (diff) | |
| download | linux-stable-fcc388ca888e1100507ff6f961b4175826f83c84.tar.gz linux-stable-fcc388ca888e1100507ff6f961b4175826f83c84.tar.bz2 linux-stable-fcc388ca888e1100507ff6f961b4175826f83c84.zip | |
serial: imx: Fix handling of TC irq in combination with DMA
commit 1866541492641c02874bf51f9d8712b5510f2c64 upstream.
When using RS485 half duplex the Transmitter Complete irq is needed to
determine the moment when the transmitter can be disabled. When using
DMA this irq must only be enabled when DMA has completed to transfer all
data. Otherwise the CPU might busily trigger this irq which is not
properly handled and so the also pending irq for the DMA transfer cannot
trigger.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
[Backport to v4.14]
Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/imx.c | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 630065b551f5..dfa2db6ed322 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -538,6 +538,11 @@ static void dma_tx_callback(void *data) if (!uart_circ_empty(xmit) && !uart_tx_stopped(&sport->port)) imx_dma_tx(sport); + else if (sport->port.rs485.flags & SER_RS485_ENABLED) { + temp = readl(sport->port.membase + UCR4); + temp |= UCR4_TCEN; + writel(temp, sport->port.membase + UCR4); + } spin_unlock_irqrestore(&sport->port.lock, flags); } @@ -555,6 +560,10 @@ static void imx_dma_tx(struct imx_port *sport) if (sport->dma_is_txing) return; + temp = readl(sport->port.membase + UCR4); + temp &= ~UCR4_TCEN; + writel(temp, sport->port.membase + UCR4); + sport->tx_bytes = uart_circ_chars_pending(xmit); if (xmit->tail < xmit->head || xmit->head == 0) { @@ -617,10 +626,15 @@ static void imx_start_tx(struct uart_port *port) if (!(port->rs485.flags & SER_RS485_RX_DURING_TX)) imx_stop_rx(port); - /* enable transmitter and shifter empty irq */ - temp = readl(port->membase + UCR4); - temp |= UCR4_TCEN; - writel(temp, port->membase + UCR4); + /* + * Enable transmitter and shifter empty irq only if DMA is off. + * In the DMA case this is done in the tx-callback. + */ + if (!sport->dma_is_enabled) { + temp = readl(port->membase + UCR4); + temp |= UCR4_TCEN; + writel(temp, port->membase + UCR4); + } } if (!sport->dma_is_enabled) { |