Messages in this thread | | | Subject | Re: [PATCH] ARM: dts: r8a7791: Don't disable referenced optional clocks | From | Sjoerd Simons <> | Date | Fri, 08 Apr 2016 12:50:54 +0200 |
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On Thu, 2016-04-07 at 16:21 -0700, Stephen Boyd wrote: > On 04/06, Sjoerd Simons wrote: > > > > On Wed, 2016-04-06 at 15:11 +0200, Geert Uytterhoeven wrote: > > > > > > CC Mike, Stephen, linux-clk (this time with the new Mike) > > > > > > On Wed, Apr 6, 2016 at 2:52 PM, Sjoerd Simons > > > <sjoerd.simons@collabora.co.uk> wrote: > > > > > > > > > > > > clk_get on a disabled clock node will return EPROBE_DEFER, > > > > which > > > > can > > > > cause drivers to be deferred forever if such clocks are > > > > referenced > > > > in > > > > their clocks property. > > > Is this a side effect of commit 3e5dd6f6e690048d ("clk: Ignore > > > disabled DT > > > clock providers")? > > Yes it seems so. Reverting that patch means that i can drop this > > one > > and get the expected behaviour again. > The DT is broken then? Is it possible to mark these status = > "okay" so that things work again?
> > > > > > Though even so I'm not sure what the convention is for clocks like > > these, the r8a7791.dtsi is inconsistent, as some are disabled while > > others (e.g. the audio clocks) are 0hz. Would be good to get some > > input > > on that regardless. > > > What's the question here?
So the question is how to model unconnected external clocks in device- tree.
The dtsi we're loooking at has (in pseudo dt):
device { clock-names = "internal", "external"; clocks = <&internal, &external> };
external { compatible = "fixed-clock"; clock-frequency = <12345>; status = "disabled"; };
Before 3e5dd6f6e690048d ("clk: Ignore disabled DT clock providers") this apparently worked. Afterwards drivers getting all the clocks would fail to probe with -EPROBE_DEFER.
Judging by your comment I assume this way of modelling it is broken (and the behaviour caused by the patch is correct)?
And as a follow-up, is modelling unconnected clocks as enabled with a frequency of 0hz as my proposed patch does seen as the right way of doing things?
-- Sjoerd Simons Collabora Ltd.
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