FAILED: patch "[PATCH] serial: amba-pl011: Fix RX stall when DMA is used" failed to apply to 6.1-stable tree

FAILED: patch "[PATCH] serial: amba-pl011: Fix RX stall when DMA is used" failed to apply to 6.1-stable tree

[gregkh]

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);
 }