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

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Message-ID: <34ae275e-8d4c-3735-c08c-4769caf2909c@linaro.org>
Date:   Tue, 2 Aug 2022 10:02:41 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Akhil P Oommen <quic_akhilpo@...cinc.com>,
        freedreno <freedreno@...ts.freedesktop.org>,
        dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Rob Clark <robdclark@...il.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Stephen Boyd <swboyd@...omium.org>
Cc:     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 30/07/2022 12:17, 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.

If this is votable, do we have any guarantee that the gdsc will collapse 
at all? How can we proceed if it did not collapse?

> 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.

Trigger the polling made me think initially that we will actually 
trigger something in the HW. Instead the client uses reset framework to 
poll for the gdsc to be reset.

> 
> This series is rebased on top of linus's master branch.
> 
> Related discussion: https://patchwork.freedesktop.org/patch/493144/
> 
> 
> 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(-)
> 


-- 
With best wishes
Dmitry