From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Lucas Stach <l.stach@pengutronix.de>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
DRI mailing list <dri-devel@lists.freedesktop.org>,
The etnaviv authors <etnaviv@lists.freedesktop.org>,
Lubomir Rintel <lkundrak@v3.sk>
Subject: Re: [PATCH 2/3] drm/etnaviv: Don't ignore errors on getting clocks
Date: Thu, 14 May 2020 09:53:08 +0100 [thread overview]
Message-ID: <20200514085307.GO1551@shell.armlinux.org.uk> (raw)
In-Reply-To: <ab384507b90474b0030d8ce64fdcfe868b52c3cb.camel@pengutronix.de>
On Thu, May 14, 2020 at 10:40:58AM +0200, Lucas Stach wrote:
> Am Donnerstag, den 14.05.2020, 09:27 +0100 schrieb Russell King - ARM Linux admin:
> > On Thu, May 14, 2020 at 10:18:02AM +0200, Lucas Stach wrote:
> > > Am Mittwoch, den 13.05.2020, 23:41 -0300 schrieb Fabio Estevam:
> > > > On Wed, May 13, 2020 at 2:09 PM Fabio Estevam <festevam@gmail.com> wrote:
> > > >
> > > > > The binding doc Documentation/devicetree/bindings/gpu/vivante,gc.yaml
> > > > > says that only the 'reg' clock could be optional, the others are
> > > > > required.
> > > >
> > > > arch/arm/boot/dts/dove.dtsi only uses the 'core' clock.
> > > > arch/arm/boot/dts/stm32mp157.dtsi uses 'bus' and 'core'
> > > >
> > > > Maybe the binding needs to be updated and it seems that using
> > > > devm_clk_get_optional() like you propose is safe.
> > >
> > > The binding is correct as-is. We want to require those clocks to be
> > > present, but the dove DT was added before the binding was finalized, so
> > > the driver still treats the clocks as optional to not break
> > > compatibility with old DTs. Maybe this warrants a comment in the
> > > code...
> >
> > The binding doc in mainline says:
> >
> > clocks:
> > items:
> > - description: AXI/master interface clock
> > - description: GPU core clock
> > - description: Shader clock (only required if GPU has feature PIPE_3D)
> > - description: AHB/slave interface clock (only required if GPU can gate slave interface independently)
> > minItems: 1
> > maxItems: 4
> >
> > clock-names:
> > items:
> > enum: [ bus, core, shader, reg ]
> > minItems: 1
> > maxItems: 4
> >
> > which looks correct to me - and means that Dove is compliant with that.
>
> The YAML binding actually did loose something in translation here,
> which I didn't notice. Previously all those clocks were listed under
> "Required properties", with the exceptions listed in parenthesis. So
> the Dove GPU, which is a combined 2D/3D core should have axi, core and
> shader clocks specified.
That may be your desire, but that is impossible without knowing that
(a) it has the clocks
(b) what those clocks are connected to
I guess we could "make something up" but as DT is supposed to describe
hardware, I don't see how we can satisfy that and your requirement.
The only thing that is known from the documentation is that there is
one clock for the GPU on Dove.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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next prev parent reply other threads:[~2020-05-14 8:53 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <[PATCH 0/3] drm/etnaviv: Clock fixes>
[not found] ` <20200513150007.1315395-1-lkundrak@v3.sk>
2020-05-13 15:00 ` [PATCH 1/3] drm/etnaviv: Fix error path on failure to enable bus clk Lubomir Rintel
2020-05-13 15:00 ` [PATCH 2/3] drm/etnaviv: Don't ignore errors on getting clocks Lubomir Rintel
2020-05-13 16:07 ` Fabio Estevam
2020-05-13 17:09 ` Fabio Estevam
2020-05-14 2:41 ` Fabio Estevam
2020-05-14 8:18 ` Lucas Stach
2020-05-14 8:27 ` Russell King - ARM Linux admin
2020-05-14 8:40 ` Lucas Stach
2020-05-14 8:53 ` Russell King - ARM Linux admin [this message]
2020-05-20 13:38 ` Lubomir Rintel
2020-05-20 14:04 ` Lucas Stach
2020-05-20 15:00 ` Russell King - ARM Linux admin
2020-05-23 10:22 ` Lubomir Rintel
2020-05-13 15:00 ` [PATCH 3/3] drm/etnaviv: Simplify clock enable/disable Lubomir Rintel
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