[PATCH 6.9 090/281] serial: 8250_pxa: Configure tx_loadsz to match FIFO IRQ level

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6.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Doug Brown <doug@xxxxxxxxxxxxx>

commit 5208e7ced520a813b4f4774451fbac4e517e78b2 upstream.

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@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240519191929.122202-1-doug@xxxxxxxxxxxxx
Cc: stable <stable@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/tty/serial/8250/8250_pxa.c |    1 +
 1 file changed, 1 insertion(+)

--- 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 platf
 	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);






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