The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 2bcacc1c87acf9a8ebc17de18cb2b3cfeca547cf # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024120356-maturing-junkman-2988@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2bcacc1c87acf9a8ebc17de18cb2b3cfeca547cf Mon Sep 17 00:00:00 2001 From: Kartik Rajput kkartik@nvidia.com Date: Wed, 13 Nov 2024 14:56:29 +0530 Subject: [PATCH] serial: amba-pl011: Fix RX stall when DMA is used

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

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 56e587b94823..2facdbcd73eb 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -1819,6 +1819,11 @@ 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); }