linux-kernel - Re: [PATCH 0/5] clk/qcom: Support gdsc collapse polling using 'reset' inteface

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Date:   Thu, 11 Aug 2022 16:45:31 +0530
From:   Akhil P Oommen <quic_akhilpo@...cinc.com>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
CC:     freedreno <freedreno@...ts.freedesktop.org>,
        <dri-devel@...ts.freedesktop.org>, <linux-arm-msm@...r.kernel.org>,
        Rob Clark <robdclark@...il.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>, <devicetree@...r.kernel.org>,
        <linux-clk@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/5] clk/qcom: Support gdsc collapse polling using 'reset'
 inteface

On 8/10/2022 2:35 AM, Bjorn Andersson wrote:
> On Sat 30 Jul 04:17 CDT 2022, Akhil P Oommen wrote:
>
>> Some clients like adreno gpu driver would like to ensure that its gdsc
>> is collapsed at hardware during a gpu reset sequence. This is because it
>> has a votable gdsc which could be ON due to a vote from another subsystem
>> like tz, hyp etc or due to an internal hardware signal. To allow
>> this, gpucc driver can expose an interface to the client driver using
>> reset framework. Using this the client driver can trigger a polling within
>> the gdsc driver.
>>
>> This series is rebased on top of linus's master branch.
>>
>> Related discussion: https://patchwork.freedesktop.org/patch/493144/
>>
> Forgive me if I'm assuming too much, but isn't this an extension of:
>
> 85a3d920d30a ("clk: qcom: Add a dummy enable function for GX gdsc")
>
> With the additional requirement that disable should really ensure that
> the GDSC is turned off?
Also, gpu driver needs a way to ensure cx gdsc was collapsed at least 
once before it goes ahead with re-init.

Btw, the patch you mentioned is about gx gdsc in gpucc which is supposed 
to be owned by gmu (except when it is in bad shape). But the current 
series is about cx gdsc which is shared with other subsystems/drivers.

-Akhil.
>
> Regards,
> Bjorn
>
>> Akhil P Oommen (5):
>>    dt-bindings: clk: qcom: Support gpu cx gdsc reset
>>    clk: qcom: Allow custom reset ops
>>    clk: qcom: gpucc-sc7280: Add cx collapse reset support
>>    clk: qcom: gdsc: Add a reset op to poll gdsc collapse
>>    arm64: dts: qcom: sc7280: Add Reset support for gpu
>>
>>   arch/arm64/boot/dts/qcom/sc7280.dtsi          |  3 +++
>>   drivers/clk/qcom/gdsc.c                       | 23 +++++++++++++++++++----
>>   drivers/clk/qcom/gdsc.h                       |  7 +++++++
>>   drivers/clk/qcom/gpucc-sc7280.c               |  6 ++++++
>>   drivers/clk/qcom/reset.c                      |  6 ++++++
>>   drivers/clk/qcom/reset.h                      |  2 ++
>>   include/dt-bindings/clock/qcom,gpucc-sc7280.h |  3 +++
>>   7 files changed, 46 insertions(+), 4 deletions(-)
>>
>> -- 
>> 2.7.4
>>