5.15-stable review patch. If anyone has any objections, please let me know.
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From: Kartik Rajput kkartik@nvidia.com
[ Upstream commit 2bcacc1c87acf9a8ebc17de18cb2b3cfeca547cf ]
Function pl011_throttle_rx() calls pl011_stop_rx() to disable RX, which also disables the RX DMA by clearing the RXDMAE bit of the DMACR register. However, to properly unthrottle RX when DMA is used, the function pl011_unthrottle_rx() is expected to set the RXDMAE bit of the DMACR register, which it currently lacks. This causes RX to stall after the throttle API is called.
Set RXDMAE bit in the DMACR register while unthrottling RX if RX DMA is used.
Fixes: 211565b10099 ("serial: pl011: UPSTAT_AUTORTS requires .throttle/unthrottle") Cc: stable@vger.kernel.org Signed-off-by: Kartik Rajput kkartik@nvidia.com Reviewed-by: Linus Walleij linus.walleij@linaro.org Link: https://lore.kernel.org/r/20241113092629.60226-1-kkartik@nvidia.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/amba-pl011.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 16fc159bdf3b9..8ae8fb8132d5b 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -1842,6 +1842,11 @@ static void pl011_unthrottle_rx(struct uart_port *port)
pl011_write(uap->im, uap, REG_IMSC);
+ if (uap->using_rx_dma) { + uap->dmacr |= UART011_RXDMAE; + pl011_write(uap->dmacr, uap, REG_DMACR); + } + uart_port_unlock_irqrestore(&uap->port, flags); }