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

From: Linus Walleij
Date: Thu May 10 2012 - 08:16:53 EST

On Thu, May 10, 2012 at 12:01 PM, Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:

> 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@xxxxxxxxxxxxxxx>
> ---
> This patch applies on top of my previous patch ("gpio: langwell: convert to
> use irq_domain").

Oh yeah that thing I recognize!
Acked-by: Linus Walleij <linus.walleij@xxxxxxxxxx>

If someone has time I think it would be a good idea to
conjure a cocienelle sematic patch to catch this pattern, because
I suspect it might exist in more IRQ handlers.

- pending = readl(gedr);
- while (pending) {
+ while ((pending = readl(gedr))) {
gpio = __ffs(pending);
mask = BIT(gpio);
- pending &= ~mask;

Linus Walleij
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