The patch below does not apply to the 5.4-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-5.4.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 '2024061757-herbal-passenger-4878@gregkh' --subject-prefix 'PATCH 5.4.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);