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serial: 8250_pxa: Configure tx_loadsz to match FIFO IRQ level

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BugLink: https://bugs.launchpad.net/bugs/2074091

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: ab28f51c77 ("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>
Signed-off-by: Portia Stephens <portia.stephens@canonical.com>
Signed-off-by: Roxana Nicolescu <roxana.nicolescu@canonical.com>
This commit is contained in:
Doug Brown
2024-05-19 12:19:30 -07:00
committed by Roxana Nicolescu
parent 90654c711b
commit c01df2aa10
1 changed files with 1 additions and 0 deletions
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drivers/tty/serial/8250/8250_pxa.c
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@@ -124,6 +124,7 @@ static int serial_pxa_probe(struct platform_device *pdev)
uart.port.regshift = 2;
uart.port.irq = irq;
uart.port.fifosize = 64;
uart.tx_loadsz = 32;
uart.port.flags = UPF_IOREMAP | UPF_SKIP_TEST | UPF_FIXED_TYPE;
uart.port.dev = &pdev->dev;
uart.port.uartclk = clk_get_rate(data->clk);