linux-kernel - Re: [PATCH v5 00/10] clk: implement clock rate protection mechanism

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Date:   Mon, 29 Jan 2018 10:22:58 +0100
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Stephen Boyd <sboyd@...eaurora.org>,
        Michael Turquette <mturquette@...libre.com>
Cc:     linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Russell King <linux@...linux.org.uk>,
        Linus Walleij <linus.walleij@...aro.org>,
        Quentin Schulz <quentin.schulz@...e-electrons.com>,
        Kevin Hilman <khilman@...libre.com>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>
Subject: Re: [PATCH v5 00/10] clk: implement clock rate protection mechanism

On Thu, 2017-12-21 at 18:15 -0800, Stephen Boyd wrote:
> On 12/19, Michael Turquette wrote:
> > Quoting Jerome Brunet (2017-12-01 13:51:50)
> > > This Patchset is related the RFC [0] and the discussion around
> > > CLK_SET_RATE_GATE available here [1]
> > > 
> > > This patchset introduce clock protection to the CCF core. This can then
> > > be used for:
> > > 
> > > * Provide a way for a consumer to claim exclusivity over the rate control
> > >   of a provider. Some clock consumers require that a clock rate must not
> > >   deviate from its selected frequency. There can be several reasons for
> > >   this, not least of which is that some hardware may not be able to
> > >   handle or recover from a glitch caused by changing the clock rate while
> > >   the hardware is in operation. For such HW, The ability to get exclusive
> > >   control of a clock's rate, and release that exclusivity, could be seen
> > >   as a fundamental clock rate control primitive. The exclusivity is not
> > >   preemptible, so when claimed more than once, is rate is effectively
> > >   locked.
> > > 
> > > * Provide a similar functionality to providers themselves, fixing
> > >   CLK_SET_RATE_GATE flag (enforce clock gating along the tree). While
> > >   there might still be a few platforms relying the broken implementation,
> > >   tests done has shown this change to be pretty safe.
> > 
> > Applied to clk-protect-rate, with the exception that I did not apply
> > "clk: fix CLK_SET_RATE_GATE with clock rate protection" as it breaks
> > qcom clk code.
> > 
> > Stephen, do you plan to fix up the qcom clock code so that the
> > SET_RATE_GATE improvement can go in?
> > 
> 
> I started working on it a while back. Let's see if I can finish
> it off this weekend.
> 

Hi Stephen,

Have you been able find something to fix the qcom code regarding this issue ?

Cheers
Jerome