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Subject: Re: [PATCH v1 1/4] clk: qcom: smd: Add XO clock for MSM8998
From:   Stephen Boyd <sboyd@kernel.org>
Message-ID: <154940592132.169292.15811923452101983358@swboyd.mtv.corp.google.com>
Cc:     marc.w.gonzalez@free.fr, andy.gross@linaro.org,
        david.brown@linaro.org, robh+dt@kernel.org, mark.rutland@arm.com,
        linux-arm-msm@vger.kernel.org, linux-clk@vger.kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        georgi.djakov@linaro.org
References: <1548866102-30224-1-git-send-email-jhugo@codeaurora.org> <1548866144-30265-1-git-send-email-jhugo@codeaurora.org> <154940408967.169292.15276398799323074789@swboyd.mtv.corp.google.com> <6e62a49a-fdb1-a087-fe83-e86aed969ae7@codeaurora.org>
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To:     Jeffrey Hugo <jhugo@codeaurora.org>, bjorn.andersson@linaro.org,
        mturquette@baylibre.com
In-Reply-To: <6e62a49a-fdb1-a087-fe83-e86aed969ae7@codeaurora.org>
Date:   Tue, 05 Feb 2019 14:32:01 -0800
Sender: linux-kernel-owner@vger.kernel.org
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Quoting Jeffrey Hugo (2019-02-05 14:15:16)
> On 2/5/2019 3:01 PM, Stephen Boyd wrote:
> > Quoting Jeffrey Hugo (2019-01-30 08:35:44)
> >> The XO clock generally feeds into other clock controllers as the parent
> >> for a lot of clock generators.
> >>
> >> Fixes: 6131dc81211c (clk: qcom: smd: Add support for MSM8998 rpm clock=
s)
> >> Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
> >=20
> > We've historically left out the XO clk because it causes problems where
> > the XO vote goes away during late init because nobody references it from
> > the rest of the clk tree and also because RPM defers probe of the system
> > and then the console blows up when it gets a clk that can't change rate.
> > See commit 54823af9cd52 ("clk: qcom: Always add factor clock for xo
> > clocks") for some more info on why we removed all the workarounds and
> > stuff around here too.
> >=20
> > So are you sure this is OK to do?
> >  =20
> >=20
>=20
> So, I've got pretty much everything as modules, and I haven't seen any=20
> issues.  However let me take a look at the commit you point out and see.
>=20

Is the name of the clk "xo_clk_src"? That isn't the name that we were
expecting the XO clk from RPM to be called. You might have to look back
at the history of the rpm clk driver on the list and see when Georgi
dropped the XO clk from it and if there was anything wrong with that. I
can't recall if this was discussed on the list or if he just told me in
some hallway conversation at Connect.