linux-kernel - Re: [PATCH v4 5/9] usb: dwc3: Rework clock initialization to be more flexible

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Date:   Wed, 30 Oct 2019 11:02:51 +0200
From:   Felipe Balbi <balbi@...nel.org>
To:     John Stultz <john.stultz@...aro.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        ShuFan Lee <shufan_lee@...htek.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Yu Chen <chenyu56@...wei.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Jun Li <lijun.kernel@...il.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Jack Pham <jackp@...eaurora.org>,
        Linux USB List <linux-usb@...r.kernel.org>,
        "open list\:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH v4 5/9] usb: dwc3: Rework clock initialization to be more flexible


Hi,

John Stultz <john.stultz@...aro.org> writes:
> On Tue, Oct 29, 2019 at 2:14 AM Felipe Balbi <balbi@...nel.org> wrote:
>> John Stultz <john.stultz@...aro.org> writes:
>>
>> > The dwc3 core binding specifies three clocks:
>> >   ref, bus_early, and suspend
>> >
>> > which are all controlled in the driver together.
>> >
>> > However some variants of the hardware my not have all three clks
>>                                         ^^
>>                                         may
>>
>> In fact *all* platforms have all three clocks. It's just that in some
>> cases clock pins are shorted together (or take input from same clock).
>>
> ...
>> another option would be to pass three clocks with the same phandle. That
>> would even make sure that clock usage counts are correct, no?
>
> Hey Felipe!
>
> So I actually had done that initially (and it seemed to work), but Rob
> suggested this way instead.
> I'm fine with either, as long as having multiple references to the
> same clk in the enable/disable paths doesn't cause trouble.
>
> Thanks so much for the review here!

same as the other patch, if we're supposed to describe the HW, then we
should describe what's actually happening.

-- 
balbi