linux-kernel - [PATCH] gpio/langwell: re-read the IRQ status register after each iteration

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Date:	Thu, 10 May 2012 13:01:22 +0300
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	linux-kernel@...r.kernel.org
Cc:	grant.likely@...retlab.ca, linus.walleij@...ricsson.com,
	Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: [PATCH] gpio/langwell: re-read the IRQ status register after each iteration

Spotted by Grant Likely. The IRQ status register should be re-read after
each iteration. Otherwise the loop misses the interrupt if it gets raised
immediately after handled.

Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
---
This patch applies on top of my previous patch ("gpio: langwell: convert to
use irq_domain").

 drivers/gpio/gpio-langwell.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/gpio-langwell.c b/drivers/gpio/gpio-langwell.c
index b067357..a1c8754 100644
--- a/drivers/gpio/gpio-langwell.c
+++ b/drivers/gpio/gpio-langwell.c
@@ -250,11 +250,9 @@ static void lnw_irq_handler(unsigned irq, struct irq_desc *desc)
 	/* check GPIO controller to check which pin triggered the interrupt */
 	for (base = 0; base < lnw->chip.ngpio; base += 32) {
 		gedr = gpio_reg(&lnw->chip, base, GEDR);
-		pending = readl(gedr);
-		while (pending) {
+		while ((pending = readl(gedr))) {
 			gpio = __ffs(pending);
 			mask = BIT(gpio);
-			pending &= ~mask;
 			/* Clear before handling so we can't lose an edge */
 			writel(mask, gedr);
 			generic_handle_irq(irq_find_mapping(lnw->domain,
-- 
1.7.9.1

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