linux-kernel - Re: [RESEND PATCH v4] clk: stm32h7: Add stm32h743 clock driver

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Date:   Fri, 30 Jun 2017 11:54:03 -0700
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     Gabriel FERNANDEZ <gabriel.fernandez@...com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@...linux.org.uk>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre TORGUE <alexandre.torgue@...com>,
        Michael Turquette <mturquette@...libre.com>,
        Nicolas Pitre <nico@...aro.org>, Arnd Bergmann <arnd@...db.de>,
        "daniel.thompson@...aro.org" <daniel.thompson@...aro.org>,
        "andrea.merello@...il.com" <andrea.merello@...il.com>,
        "radoslaw.pietrzyk@...il.com" <radoslaw.pietrzyk@...il.com>,
        Lee Jones <lee.jones@...aro.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        Ludovic BARRE <ludovic.barre@...com>,
        Olivier BIDEAU <olivier.bideau@...com>,
        Amelie DELAUNAY <amelie.delaunay@...com>,
        "gabriel.fernandez.st@...il.com" <gabriel.fernandez.st@...il.com>
Subject: Re: [RESEND PATCH v4] clk: stm32h7: Add stm32h743 clock driver

On 06/30, Gabriel FERNANDEZ wrote:
> 
> 
> On 06/30/2017 02:20 AM, Stephen Boyd wrote:
> > On 06/29, Gabriel FERNANDEZ wrote:
> >>
> >> On 06/28/2017 05:59 PM, Stephen Boyd wrote:
> >>> On 06/27, Gabriel FERNANDEZ wrote:
> >>>> On 06/22/2017 12:07 AM, Stephen Boyd wrote:
> >>>>> readl_poll_timeout?
> >>>>>
> >>>> if i use readl_poll_timeout (wich use 'ktime_get()') it can be
> >>>> operational only after the selection of clocksource ? (device_initcall).
> >>>> And then if a driver turn on a clock before, it could blocked the linux
> >>>> console ?
> >>>>
> >>> Ok. I wonder if we could add some sort of starting check to
> >>> readl_poll_timeout() that tests system_state for booting vs.
> >>> scheduling? That should be sufficient to handle this case?
> >>>
> >> Oops i think i understood my problem...
> >> i used readl_poll_timeout in atomic context.
> >> I have to move my code in the .prepare ops.
> >>
> >> If you are ok with that i will send a v5
> >>
> > There's readl_poll_timeout_atomic() for those modes.
> >
> yes it's exactly the test i made (use 'readl_poll_timeout()_atomic' in 
> .enable ops) but i'm blocked.
> 
> if i do the same in .prepare ops with 'readl_poll_timeout()' it's ok.

I'm still confused. readl_poll_timeout_atomic() uses ktime_get(),
and so does readl_poll_timeout(), so how does moving to the
prepare op fix the problem? What's the actual problem?

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