Re: [PATCH v3 00/15] Bring suspend to RAM support to PCIe Aardvark driver

From: Lorenzo Pieralisi
Date: Fri Jan 25 2019 - 07:40:23 EST


On Fri, Jan 25, 2019 at 11:05:30AM +0100, Miquel Raynal wrote:
> Hi Lorenzo,
>
> Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> wrote on Wed, 23 Jan 2019
> 17:05:09 +0000:
>
> > On Tue, Jan 08, 2019 at 05:24:25PM +0100, Miquel Raynal wrote:
> > > Hello,
> > >
> > > As part of an effort to bring suspend to RAM support to Armada 3700
> > > SoCs (main target: ESPRESSObin), this series handles the work around
> > > the PCIe IP.
> > >
> > > First, more configuration is done in the 'setup' helper as inspired
> > > from the U-Boot driver. This is needed to entirely initialize the IP
> > > during future resume operation (patch 1).
> > >
> > > Then, reset GPIO, PHY and clock support are introduced (patch 2-4). As
> > > current device trees do not provide the corresponding properties, not
> > > finding one of these properties is not an error and just produces a
> > > warning. However, if the property is present, an error during PHY
> > > initialization will fail the probe of the driver.
> > >
> > > Note: To be sure the clock will be resumed before this driver, a first
> > > series adding links between clocks and consumers has been submitted,
> > > see [1]. Anyway, having the clock series applied first is not needed.
> >
> > I do not understand what this means, in particular in relation
> > to the blocking clock calls in the suspend/resume NOIRQ hooks.
>
> I am not sure to understand your question.
>
> As there are multiple points in this sentence I will detail each of
> them so please comment on the one which is bothering you:
> * I am working in parallel on a series adding device links to the clock
> framework. This way when a driver consumes a clock, the clock
> provider driver will be resumed first.
> * If the clock series I am talking about is applied after this one,
> there is no build issue. Of course suspending the platform may
> not work but this is a new feature so nothing will be broken.

Suspend to RAM will be broken if the clock is suspended and no
notification will happen in the NOIRQ phase, it is a new-broken-feature.

> * Device links do not enforce any priority if the suspend/resume phase
> between two drivers is not the same. The PCIe driver suspends in the
> NOIRQ phase. If we want the clock driver to suspend *after* PCIe, its
> suspend/resume callbacks must be promoted to the NOIRQ phase as well
> (and this is part of another series). As of today there is
> no alternative.

I will merge this series when it works, I have no evidence that it does
given what you are writing above, if the series you mention are
*necessary* for suspend-to-RAM to work they ought to be merged first.

Thanks,
Lorenzo