From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S933947AbdGKQeu (ORCPT <rfc822;w@1wt.eu>);
        Tue, 11 Jul 2017 12:34:50 -0400
Received: from muru.com ([72.249.23.125]:54248 "EHLO muru.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S932526AbdGKQes (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 11 Jul 2017 12:34:48 -0400
Date: Tue, 11 Jul 2017 09:34:34 -0700
From: Tony Lindgren <tony@atomide.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Sebastian Reichel <sebastian.reichel@collabora.co.uk>,
        LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Ingo Molnar <mingo@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
        Pavel Machek <pavel@ucw.cz>, Linus Walleij <linus.walleij@linaro.org>,
        Grygorii Strashko <grygorii.strashko@ti.com>
Subject: Re: [GIT pull] irq updates for 4.13
Message-ID: <20170711163433.GB3730@atomide.com>
References: <alpine.DEB.2.20.1707091044210.2493@nanos>
 <20170710133505.eo6w73kq2327n34p@earth>
 <CA+55aFz5=ubNvhTUTzk3kFuLMFToP7xh7h8NDXDor9w+cjsCBA@mail.gmail.com>
 <alpine.DEB.2.20.1707110815440.1799@nanos>
 <alpine.DEB.2.20.1707110933590.1799@nanos>
 <20170711135131.GW3730@atomide.com>
 <alpine.DEB.2.20.1707111636180.1799@nanos>
 <CA+55aFwDgG6tZeqX7QPwxvwK8MMn_+RSkOgfG_jxzKkzySV6vw@mail.gmail.com>
 <alpine.DEB.2.20.1707111815280.1799@nanos>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <alpine.DEB.2.20.1707111815280.1799@nanos>
User-Agent: Mutt/1.8.2 (2017-04-18)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

* Thomas Gleixner <tglx@linutronix.de> [170711 09:20]:
> On Tue, 11 Jul 2017, Linus Torvalds wrote:
> 
> > On Tue, Jul 11, 2017 at 7:41 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
> > >
> > > Ah. Now that makes sense.
> > >
> > > Unpatched the ordering is:
> > >
> > >           chip_bus_lock(desc);
> > >           irq_request_resources(desc);
> > 
> > I *looked* at that ordering and then went "Naah, that makes no sense".
> > 
> > But if that's the only issue, how about we just re-order those things
> > - we still don't need to move the irq_request_resources() into the
> > spinlock, we just move it to below the chip_bus_lock().
> > 
> > IOW, something like the (COMPLETELY UNTEESTED!) attached patch.
> > 
> > This assumes that the chip_bus_lock() thing is still ok for the RT
> > case, but it looks like it might be: the only other one I looked at
> > (apart from the gpio-omap one) used a mutex.
> 
> I looked through all of them and the only special case is gpio-omap.
> 
> What I do not understand here is that we have already power management
> around all of that.
> 
>        irq_chip_pm_get(&desc->irq_data);
>        ...
>        chip_bus_lock(desc);
>        ...
>        chip_bus_unlock_sync(desc);
>        ...
>        irq_chip_pm_put(&desc->irq_data);
> 
> So why is that not sufficient and needs extra magic in that GPIO driver?

Yeah it seems we should eventually be able to use irq_chip_pm_get()
like Grygorii just explained.

But aren't we currently calling chip functions with irq_request_resources()
outside the chip_bus_lock() too in addition to the gpio-omap runtime PM
issue? It seems that the patch from Linus fixes that, no?

Regards,

Tony