patch "serial: 8250_exar: Read INT0 from slave device, too" added to tty-next

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    serial: 8250_exar: Read INT0 from slave device, too

to my tty git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-next branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release
during the merge window.

If you have any questions about this process, please let me know.


>From 60ab0fafc4b652fcaf7cbc3bb8555a0cf1149c28 Mon Sep 17 00:00:00 2001
From: Aaron Sierra <asierra@xes-inc.com>
Date: Tue, 24 Jul 2018 14:23:46 -0500
Subject: serial: 8250_exar: Read INT0 from slave device, too

The sleep wake-up refactoring that I introduced in

  commit c7e1b4059075 ("tty: serial: exar: Relocate sleep wake-up handling")

did not account for devices with a slave device on the expansion port.
This patch pokes the INT0 register in the slave device, if present, in
order to ensure that MSI interrupts don't get permanently "stuck"
because of a sleep wake-up interrupt as described here:

  commit 2c0ac5b48a35 ("serial: exar: Fix stuck MSIs")

This also converts an ioread8() to readb() in order to provide visual
consistency with the MMIO-only accessors used elsewhere in the driver.

Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Fixes: c7e1b4059075 ("tty: serial: exar: Relocate sleep wake-up handling")
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/8250/8250_exar.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index 7a98acd5e171..0089aa305ef9 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -445,7 +445,11 @@ static irqreturn_t exar_misc_handler(int irq, void *data)
 	struct exar8250 *priv = data;
 
 	/* Clear all PCI interrupts by reading INT0. No effect on IIR */
-	ioread8(priv->virt + UART_EXAR_INT0);
+	readb(priv->virt + UART_EXAR_INT0);
+
+	/* Clear INT0 for Expansion Interface slave ports, too */
+	if (priv->board->num_ports > 8)
+		readb(priv->virt + 0x2000 + UART_EXAR_INT0);
 
 	return IRQ_HANDLED;
 }
-- 
2.18.0