linux-kernel - Re: [PATCH RFT v2 00/14] SMD RPMCC sleep preparations

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Message-ID: <b9b6e799-c8a2-7d8c-4d87-56d899048454@linaro.org>
Date:   Thu, 20 Apr 2023 12:20:39 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Stephan Gerhold <stephan@...hold.net>
Cc:     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>,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        devicetree@...r.kernel.org, Shawn Guo <shawn.guo@...aro.org>,
        Taniya Das <quic_tdas@...cinc.com>
Subject: Re: [PATCH RFT v2 00/14] SMD RPMCC sleep preparations



On 20.04.2023 12:04, Stephan Gerhold wrote:
> On Thu, Apr 20, 2023 at 11:36:24AM +0200, Konrad Dybcio wrote:
>> On 20.04.2023 09:56, Stephan Gerhold wrote:
>>> On Thu, Apr 20, 2023 at 03:50:16AM +0200, Konrad Dybcio wrote:
>>>> On 8.03.2023 22:35, Konrad Dybcio wrote:
>>>>> Keepalive clocks for other platforms were gathered by digging in old
>>>>> downstream kernels, please give them a test.
>>>> I have an implementation of rpmcc-within-icc ready(ish) locally. Turns out
>>>> some SoCs need a keepalive (19.2MHz, active-only) vote on clocks that
>>>> are NOT governed by interconnect.. So before we can disable clocks,
>>>> both will need to be implemented.. ugh... I was hoping we could avoid
>>>> having it in rpmcc..
>>> Can you give an example? Which clocks are affected on which SoC?
>> msm8998/sdm660 and PNoC
> 
> I don't see a PNoC for 8998/660, do you mean the "cnoc_periph_clk"
It's the same, but Qualcomm kept changing the name every kernel
release, so that's why we have 50 defines for the same thing
upstream :(


> downstream? Like the other NoCs it seems to be a RPM_BUS_CLK_TYPE, which
> means it does fit best into interconnect in my opinion. From a quick
> grep I don't see any usage of it in msm-4.4 downstream other than the
> active-only keepalive vote. So maybe you could just send that vote once
> in icc_rpm_smd and then ignore that clock (don't expose it at all)?
Hm, perhaps that does sound like a good idea! As far as I understand,
it's governed internally.. Older SoCs had a separate PNoC fabric
exposed.

Konrad

> 
> Thanks,
> Stephan