Re: [PATCH v18 1/5] iommu/arm-smmu: Add pm_runtime/sleep ops

From: Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>
To: Vivek Gautam <vivek.gautam-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
Cc: Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
	Linux PM <linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	sboyd-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
	linux-arm-msm
	<linux-arm-msm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>,
	"Rafael J. Wysocki" <rjw-LthD3rsA81gm4RdzfppkhA@public.gmane.org>,
	open list <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
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	<iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>,
	Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>,
	"
	<iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>,
	robh+dt <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	freedreno
	<freedreno-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>,
	Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
Subject: Re: [PATCH v18 1/5] iommu/arm-smmu: Add pm_runtime/sleep ops
Date: Fri, 30 Nov 2018 18:15:37 +0000	[thread overview]
Message-ID: <20181130181536.GA15274@arm.com> (raw)
In-Reply-To: <CAFp+6iEC8hobAdVF5nLdhQdCUqbi1xa4Vi-NLugGshV=dg+h1A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Thu, Nov 29, 2018 at 08:25:20PM +0530, Vivek Gautam wrote:
> On Wed, Nov 28, 2018 at 10:07 PM Robin Murphy <robin.murphy@arm.com> wrote:
> >
> > On 28/11/2018 16:24, Stephen Boyd wrote:
> > > Quoting Vivek Gautam (2018-11-27 02:11:41)
> > >> @@ -1966,6 +1970,23 @@ static const struct of_device_id arm_smmu_of_match[] = {
> > >>   };
> > >>   MODULE_DEVICE_TABLE(of, arm_smmu_of_match);
> > >>
> > >> +static void arm_smmu_fill_clk_data(struct arm_smmu_device *smmu,
> > >> +                                  const char * const *clks)
> > >> +{
> > >> +       int i;
> > >> +
> > >> +       if (smmu->num_clks < 1)
> > >> +               return;
> > >> +
> > >> +       smmu->clks = devm_kcalloc(smmu->dev, smmu->num_clks,
> > >> +                                 sizeof(*smmu->clks), GFP_KERNEL);
> > >> +       if (!smmu->clks)
> > >> +               return;
> > >> +
> > >> +       for (i = 0; i < smmu->num_clks; i++)
> > >> +               smmu->clks[i].id = clks[i];
> > >
> > > Is this clk_bulk_get_all()?
> 
> From what I remember, and now I could go back to v7 and check [1], we parked
> clk_bulk_get out of OF's sole purview as we also have
> arm_smmu_device_acpi_probe() besides arm_smmu_device_dt_probe().
> 
> arm_smmu_device_dt_probe() could get the clocks from dt and fill in
> the clock bulk data, and
> similarly, arm_smmu_device_acpi_probe() could fill the clock bulk data
> by getting it from ACPI.
> 
> clk_bulk_get_all() seems like going only the OF way.
> Is there another way here to have something common between ACPI
> and OF, and then do the clk_bulk_get?

I'd say just go with clk_bulk_get_all() and if somebody really wants to
mess with the SMMU clocks on a system booted via ACPI, then it's their
problem to solve. My understanding is that the design of IORT makes this
next to impossible to solve anyway, because a static table is used and
therefore we're unable to run whatever ASL methods need to be invoked to
mess with the clocks.

Will
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