linux-kernel - Re: [PATCH] clk: qcom: mmcc-msm8974: remove ocmemcx_ahb

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Message-ID: <091e4156-cdaa-4233-b7e5-69e3f8ee9a49@linaro.org>
Date:   Sat, 2 Sep 2023 22:28:09 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Luca Weiss <luca@...tu.xyz>, ~postmarketos/upstreaming@...ts.sr.ht,
        phone-devel@...r.kernel.org, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Mike Turquette <mturquette@...aro.org>
Cc:     Stephen Boyd <sboyd@...eaurora.org>, linux-arm-msm@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH] clk: qcom: mmcc-msm8974: remove ocmemcx_ahb_clk

On 2.09.2023 19:34, Luca Weiss wrote:
> According to a commit in the 3.4 vendor kernel sources[0] the
> ocmemcx_ahb_clk clock "is controlled by RPM and should not be touched by
> APPS.".
> 
> [0] https://git.codelinaro.org/clo/la/kernel/msm/-/commit/37df5f2d91b4d5768b37fcaacaeea958dd683ebc
> 
> And indeed, when using MDSS+GPU+OCMEM on MSM8226 and not using
> clk_ignore_unused, when Linux tries to disable the clock the device
> crashes and reboots.
> 
> And since there's also no evidence of this clock in msm8974 vendor
> kernel sources, remove the clock for msm8226 and msm8974.
Going over the downstream clock driver for 26 and 74 and comparing
the registered clocks with mainline may be useful.

Older clock drivers were likely written by hand and people doing
that likely didn't have a great reference of which clocks should
be skipped due to having been moved to firmware somewhere in the
bringup process.

Reviewed-by: Konrad Dybcio <konrad.dybcio@...aro.org>

Konrad