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serial: amba-pl011: Fix DMA transmission in RS485 mode

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When DMA is used in RS485 mode make sure that the UARTs tx section is
enabled before the DMA buffers are queued for transmission.

Cc: stable@vger.kernel.org
Fixes: 8d47923772 ("serial: amba-pl011: add RS485 support")
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Link: https://lore.kernel.org/r/20240216224709.9928-2-l.sanfilippo@kunbus.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lino Sanfilippo 2024-02-16 23:47:08 +01:00 committed by Greg Kroah-Hartman
parent f418ae7331
commit 3b69e32e15
1 changed files with 30 additions and 30 deletions
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60
drivers/tty/serial/amba-pl011.c
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@ -1339,11 +1339,41 @@ static void pl011_start_tx_pio(struct uart_amba_port *uap)
}
}
static void pl011_rs485_tx_start(struct uart_amba_port *uap)
{
struct uart_port *port = &uap->port;
u32 cr;
/* Enable transmitter */
cr = pl011_read(uap, REG_CR);
cr |= UART011_CR_TXE;
/* Disable receiver if half-duplex */
if (!(port->rs485.flags & SER_RS485_RX_DURING_TX))
cr &= ~UART011_CR_RXE;
if (port->rs485.flags & SER_RS485_RTS_ON_SEND)
cr &= ~UART011_CR_RTS;
else
cr |= UART011_CR_RTS;
pl011_write(cr, uap, REG_CR);
if (port->rs485.delay_rts_before_send)
mdelay(port->rs485.delay_rts_before_send);
uap->rs485_tx_started = true;
}
static void pl011_start_tx(struct uart_port *port)
{
struct uart_amba_port *uap =
container_of(port, struct uart_amba_port, port);
if ((uap->port.rs485.flags & SER_RS485_ENABLED) &&
!uap->rs485_tx_started)
pl011_rs485_tx_start(uap);
if (!pl011_dma_tx_start(uap))
pl011_start_tx_pio(uap);
}
@ -1424,42 +1454,12 @@ static bool pl011_tx_char(struct uart_amba_port *uap, unsigned char c,
return true;
}
static void pl011_rs485_tx_start(struct uart_amba_port *uap)
{
struct uart_port *port = &uap->port;
u32 cr;
/* Enable transmitter */
cr = pl011_read(uap, REG_CR);
cr |= UART011_CR_TXE;
/* Disable receiver if half-duplex */
if (!(port->rs485.flags & SER_RS485_RX_DURING_TX))
cr &= ~UART011_CR_RXE;
if (port->rs485.flags & SER_RS485_RTS_ON_SEND)
cr &= ~UART011_CR_RTS;
else
cr |= UART011_CR_RTS;
pl011_write(cr, uap, REG_CR);
if (port->rs485.delay_rts_before_send)
mdelay(port->rs485.delay_rts_before_send);
uap->rs485_tx_started = true;
}
/* Returns true if tx interrupts have to be (kept) enabled */
static bool pl011_tx_chars(struct uart_amba_port *uap, bool from_irq)
{
struct circ_buf *xmit = &uap->port.state->xmit;
int count = uap->fifosize >> 1;
if ((uap->port.rs485.flags & SER_RS485_ENABLED) &&
!uap->rs485_tx_started)
pl011_rs485_tx_start(uap);
if (uap->port.x_char) {
if (!pl011_tx_char(uap, uap->port.x_char, from_irq))
return true;