This is a note to let you know that I've just added the patch titled
serial: amba-pl011: Fix DMA transmission in RS485 mode
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-amba-pl011-fix-dma-transmission-in-rs485-mode.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3b69e32e151bc4a4e3c785cbdb1f918d5ee337ed Mon Sep 17 00:00:00 2001
From: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
Date: Fri, 16 Feb 2024 23:47:08 +0100
Subject: serial: amba-pl011: Fix DMA transmission in RS485 mode
From: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
commit 3b69e32e151bc4a4e3c785cbdb1f918d5ee337ed upstream.
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@xxxxxxxxxxxxxxx
Fixes: 8d479237727c ("serial: amba-pl011: add RS485 support")
Signed-off-by: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240216224709.9928-2-l.sanfilippo@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/amba-pl011.c | 60 ++++++++++++++++++++--------------------
1 file changed, 30 insertions(+), 30 deletions(-)
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1345,11 +1345,41 @@ static void pl011_start_tx_pio(struct ua
}
}
+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);
}
@@ -1431,42 +1461,12 @@ static bool pl011_tx_char(struct uart_am
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;
Patches currently in stable-queue which might be from l.sanfilippo@xxxxxxxxxx are
queue-6.6/serial-amba-pl011-fix-dma-transmission-in-rs485-mode.patch
queue-6.6/serial-stm32-do-not-always-set-ser_rs485_rx_during_tx-if-rs485-is-enabled.patch
