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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CALieaeeVfDe8GBFO6O_=_Z5W+y7==WWbD8x-596EAw-qMXf9ZQ@mail.gmail.com>
Date: Mon, 17 Feb 2025 22:18:22 +0300
From: Dmitry Mastykin <mastichi@...il.com>
To: Linus Walleij <linus.walleij@...aro.org>
Cc: Sebastian Reichel <sre@...nel.org>, 
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"e.shatokhin@...ro.com" <e.shatokhin@...ro.com>, 
	"arturas.moskvinas@...il.com" <arturas.moskvinas@...il.com>
Subject: Re: [PATCH] pinctrl: mcp23s08: Get rid of spurious level interrupts

Thank you, Linus. No, I have no users. It's only a prototype, using a
touchscreen. I think it has to be redesigned using chipset interrupt
controller's pin instead of the expander to speed-up, although I don't
feel touch gets slower. I spoke about hypothetical users who may use
the expander as an interrupt controller at rates comparable to
mcp23s08_irq() execution time, and may get less interrupts per second.
Kind regards,
Dmitry

On Fri, Feb 14, 2025 at 12:10 PM Linus Walleij <linus.walleij@...aro.org> wrote:
>
> On Fri, Feb 7, 2025 at 9:36 PM Dmitry Mastykin <mastichi@...il.com> wrote:
>
> > I made more tests and think that this patch shouldn't be applied.
> > It removes duplicated interrupts, but sometimes they increase the performance:
> > a new interrupt may come during handling a spurious one, and spurious one will
> > become valid (it's kind of a polling). I see the number of my touchscreen
> > interrupts reduced from 200 to 130 per second with this patch. It may be a bigger
> > problem for users, than duplicated interrupts. Sorry.
>
> Don't be sorry about that, we code and learn by our mistakes.
>
> So is this patch causing any regression for users? Like touch
> events being slow to react? Also the expander could be used
> for other things than touchscreens. If it's not causing any regression
> for users it seems like a reasonable patch.
>
> Yours,
> Linus Walleij