linux-kernel - Re: [PATCH 05/12] PCI: aardvark: add suspend to RAM support

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Message-ID: <61805564.abKDZ2rVK7@aspire.rjw.lan>
Date:   Thu, 13 Dec 2018 22:50:51 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Stephen Boyd <sboyd@...nel.org>, sudeep.holla@....com,
        Gregory Clement <gregory.clement@...tlin.com>,
        Jason Cooper <jason@...edaemon.net>,
        Andrew Lunn <andrew@...n.ch>,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        devicetree@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Antoine Tenart <antoine.tenart@...tlin.com>,
        Maxime Chevallier <maxime.chevallier@...tlin.com>,
        Nadav Haklai <nadavh@...vell.com>
Subject: Re: [PATCH 05/12] PCI: aardvark: add suspend to RAM support

On Thursday, December 13, 2018 3:30:00 PM CET Miquel Raynal wrote:
> Hi Lorenzo,
> 
> > > If that's really the case, then I can see how one device and it's
> > > children are suspended and the irq for it is disabled but the providing
> > > devices (clk, regulator, bus controller, etc.) are still fully active
> > > and not suspended but in fact completely usable and able to service
> > > interrupts. If that all makes sense, then I would answer the question
> > > with a definitive "yes it's all fine" because the clk consumer could be
> > > in the NOIRQ phase of its suspend but the clk provider wouldn't have
> > > even started suspending yet when clk_disable_unprepare() is called.  
> > 
> > That's a very good summary and address my concern, I still question this
> > patch correctness (and many others that carry out clk operations in S2R
> > NOIRQ phase), they may work but do not tell me they are rock solid given
> > your accurate summary above.
> 
> I understand your concern but I don't see any alternative right now
> and a deep rework of the PM core to respect such dependency is not
> something that can be done in a reasonable amount of time.

Maybe you don't need to rework anything. :-)

Have you considered using device links?

Thanks,
Rafael