linux-kernel - Re: [PATCH] pinctrl: mcp23s08: Get rid of spurious level interrupts

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Message-ID: <d26ukzhmjmvqle5zsc54lhnfaaheg5cox6hdttt42frj3sbwb4@eryduawlkyka>
Date: Sat, 8 Feb 2025 18:33:35 +0100
From: Sebastian Reichel <sre@...nel.org>
To: Linus Walleij <linus.walleij@...aro.org>
Cc: Dmitry Mastykin <mastichi@...il.com>, linux-gpio@...r.kernel.org, 
	linux-kernel@...r.kernel.org, e.shatokhin@...ro.com, arturas.moskvinas@...il.com
Subject: Re: [PATCH] pinctrl: mcp23s08: Get rid of spurious level interrupts

Hi,

On Thu, Feb 06, 2025 at 10:25:51AM +0100, Linus Walleij wrote:
> On Wed, Jan 22, 2025 at 1:05 PM Dmitry Mastykin <mastichi@...il.com> wrote:
> 
> > irq_mask()/irq_unmask() are not called for nested interrupts. So level
> > interrupts are never masked, chip's interrupt output is not cleared on
> > INTCAP or GPIO read, the irq handler is uselessly called again. Nested
> > irq handler is not called again, because interrupt reason is cleared by
> > its first call.
> > /proc/interrupts shows that number of chip's irqs is greater than
> > number of nested irqs.
> >
> > This patch adds masking and unmasking level interrupts inside irq handler.
> >
> > Signed-off-by: Dmitry Mastykin <mastichi@...il.com>
> 
> Patch tentatively applied as non-urgent fix.
> 
> If this is urgent, I need a Fixes: tags and we should also tag it
> for stable, is this a big problem for users? I don't have the big picture
> here.
> 
> Adding Sebastian, if he's still using this expander.

I use the 16 bit I2C version of this chip in the hackerspace
together with gpio-keys and haven't noticed any IRQ issues. But the
system is running a Debian stable (incl. its kernel), so quite far
from mainline :)

Greetings,

-- Sebastian

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