The current 8250 timeout code duplicates the code path in
serial8250_default_handle_irq and then serial8250_handle_irq
i.e. reading iir, check for IIR_NO_INT, and then calling
serial8250_handle_port.

So the immediate thought is to replace the duplicated code
with a call to serial8250_default_handle_irq.

But this highlights a problem.  We let 8250 driver variants
use their own IRQ handler via specifying their own custom
->handle_irq, but in the event of a timeout, we ignore their
handler and implicitly run serial8250_default_handle_irq instead.

So, go through the struct to get ->handle_irq and call that,
which for most will still be serial8250_default_handle_irq.

Signed-off-by: Paul Gortmaker <redacted>
---
 drivers/tty/serial/8250.c |    5 +----
 1 files changed, 1 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
index 91afe7a..9e7780d 100644
--- a/drivers/tty/serial/8250.c
+++ b/drivers/tty/serial/8250.c

@@ -1738,11 +1738,8 @@ static void serial_unlink_irq_chain(struct uart_8250_port *up)
 static void serial8250_timeout(unsigned long data)
 {
 	struct uart_8250_port *up = (struct uart_8250_port *)data;
-	unsigned int iir;
 
-	iir = serial_in(up, UART_IIR);
-	if (!(iir & UART_IIR_NO_INT))
-		serial8250_handle_port(up);
+	up->port.handle_irq(&up->port);
 	mod_timer(&up->timer, jiffies + uart_poll_timeout(&up->port));
 }
 

-- 
1.7.7