linux-kernel - Re: [PATCH v1 2/2] clk: qcom: dispcc: Remove support of disp_cc_mdss_rscc_ahb

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Message-ID: <158438359728.88485.9249991203602274851@swboyd.mtv.corp.google.com>
Date:   Mon, 16 Mar 2020 11:33:17 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Matthias Kaehlcke <mka@...omium.org>,
        Taniya Das <tdas@...eaurora.org>
Cc:     Michael Turquette <mturquette@...libre.com>, robh@...nel.org,
        David Brown <david.brown@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andy Gross <agross@...nel.org>, devicetree@...r.kernel.org,
        robh+dt@...nel.org, Doug Anderson <dianders@...omium.org>
Subject: Re: [PATCH v1 2/2] clk: qcom: dispcc: Remove support of disp_cc_mdss_rscc_ahb_clk

Quoting Taniya Das (2020-03-14 04:08:47)
> I would require you suggestion on the below.
> 
> On 3/13/2020 11:31 PM, Stephen Boyd wrote:
> > Quoting Matthias Kaehlcke (2020-03-04 09:09:39)
> >> Hi Taniya,
> >>
> >> On Wed, Mar 04, 2020 at 09:05:20AM +0530, Taniya Das wrote:
> >>>
> >>> Hi Matthias,
> >>>
> >>> The display device node is not present and we encounter this crash, would it
> >>> be possible to add ALWAYS_ON for the MDSS GDSC and give it a try.
> >>
> >> It still crashes when ALWAYS_ON is set for the MDSS GDSC.
> > 
> > Any updates here? I'm about to send this patch off to Linus and I'm
> > wondering if there will be a resolution besides reverting it.
> > 
> 
> Looks like the AHB clock needs to be left enabled till the last clocks 
> get disabled. I need to add a new dependency o n this clock.
> 
> Hi Stephen,
> 
> 
> Any way to keep this dependency using the framework  or I need to split 
> the probes to register them independently?
> 

Sorry, I don't understand the problem fully. This AHB clk is left on in
the bootloader? Why do we need to touch it if it's always left enabled?
Is it actually the case that the bootloader hasn't turned this clk on
and we're getting lucky having it marked here as CLK_IS_CRITICAL? Can we
force it on in driver probe and then ignore it after that?