linux-kernel - Re: [PATCH] clk: qcom: rcg2: Cache rate changes for parked RCGs

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Date:   Fri, 3 Dec 2021 21:16:47 -0600
From:   Steev Klimaszewski <steev@...i.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Amit Nischal <anischal@...eaurora.org>,
        Taniya Das <tdas@...eaurora.org>
Cc:     dmitry.baryshkov@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: qcom: rcg2: Cache rate changes for parked RCGs


On 12/3/21 6:39 PM, Steev Klimaszewski wrote:
>
> On 12/2/21 9:56 PM, Bjorn Andersson wrote:
>> As GDSCs are turned on and off some associated clocks are momentarily
>> enabled for house keeping purposes. Failure to enable these clocks seems
>> to have been silently ignored in the past, but starting in SM8350 this
>> failure will prevent the GDSC to turn on.
>>
>> At least on SM8350 this operation will enable the RCG per the
>> configuration in CFG_REG. This means that the current model where the
>> current configuration is written back to CF_REG immediately after
>> parking the RCG doesn't work.
>>
>> Instead, keep track of the currently requested rate of the clock and
>> upon enabling the clock reapply the configuration per the saved rate.
>>
>> Fixes: 7ef6f11887bd ("clk: qcom: Configure the RCGs to a safe source 
>> as needed")
>> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
>> ---
>>   drivers/clk/qcom/clk-rcg.h  |  2 ++
>>   drivers/clk/qcom/clk-rcg2.c | 32 +++++++++++++++++---------------
>>   2 files changed, 19 insertions(+), 15 deletions(-)
>>
>> <snip patch>
>
> With this applied, I'm getting
> <snip>

Actually turns out, I had a testing patch in from Dmitry that I'd never 
taken back out when it was decided it wasn't good enough. Apologies for 
the useless message.  This does not actually cause the issue, just the 
combination of them does.

Tested on the Lenovo Yoga C630

Tested-By: Steev Klimaszewski <steev@...i.org>