FAILED: patch "[PATCH] serial: 8250_pxa: Configure tx_loadsz to match FIFO IRQ level" failed to apply to 4.19-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.19-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-4.19.y
git checkout FETCH_HEAD
git cherry-pick -x 5208e7ced520a813b4f4774451fbac4e517e78b2
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024061758-junkyard-thimble-efb0@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

5208e7ced520 ("serial: 8250_pxa: Configure tx_loadsz to match FIFO IRQ level")
cc6628f07e0d ("serial: 8250_pxa: Switch to use uart_read_port_properties()")
e914072cacb6 ("serial: 8250_pxa: Switch to use platform_get_irq()")
8c6b6ffac367 ("serial: 8250_pxa: avoid autodetecting the port type")

thanks,

greg k-h

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

From 5208e7ced520a813b4f4774451fbac4e517e78b2 Mon Sep 17 00:00:00 2001
From: Doug Brown <doug@schmorgal.com>
Date: Sun, 19 May 2024 12:19:30 -0700
Subject: [PATCH] serial: 8250_pxa: Configure tx_loadsz to match FIFO IRQ level

The FIFO is 64 bytes, but the FCR is configured to fire the TX interrupt
when the FIFO is half empty (bit 3 = 0). Thus, we should only write 32
bytes when a TX interrupt occurs.

This fixes a problem observed on the PXA168 that dropped a bunch of TX
bytes during large transmissions.

Fixes: ab28f51c77cd ("serial: rewrite pxa2xx-uart to use 8250_core")
Signed-off-by: Doug Brown <doug@schmorgal.com>
Link: https://lore.kernel.org/r/20240519191929.122202-1-doug@schmorgal.com
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_pxa.c b/drivers/tty/serial/8250/8250_pxa.c
index f1a51b00b1b9..ba96fa913e7f 100644
--- a/drivers/tty/serial/8250/8250_pxa.c
+++ b/drivers/tty/serial/8250/8250_pxa.c
@@ -125,6 +125,7 @@ static int serial_pxa_probe(struct platform_device *pdev)
 	uart.port.iotype = UPIO_MEM32;
 	uart.port.regshift = 2;
 	uart.port.fifosize = 64;
+	uart.tx_loadsz = 32;
 	uart.dl_write = serial_pxa_dl_write;
 
 	ret = serial8250_register_8250_port(&uart);