linux-kernel - Re: [PATCH v2 0/3] phy: qcom-qmp-pcie: Add support to keep refclk always on

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Date:   Thu, 9 Nov 2023 15:02:01 +0530
From:   Krishna Chaitanya Chundru <quic_krichai@...cinc.com>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Vinod Koul <vkoul@...nel.org>,
        "Kishon Vijay Abraham I" <kishon@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
CC:     <linux-arm-msm@...r.kernel.org>, <linux-phy@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <quic_vbadigan@...cinc.com>, <quic_ramkri@...cinc.com>,
        <quic_nitegupt@...cinc.com>, <quic_skananth@...cinc.com>,
        <quic_vpernami@...cinc.com>, <quic_parass@...cinc.com>
Subject: Re: [PATCH v2 0/3] phy: qcom-qmp-pcie: Add support to keep refclk
 always on


On 11/8/2023 3:27 AM, Konrad Dybcio wrote:
>
>
> On 11/7/23 13:26, Krishna chaitanya chundru wrote:
>> This series adds support to provide refclk to endpoint even in low
>> power states.
>>
>> Due to some platform specific issues with CLKREQ signal, it is not being
>> propagated to the host and as host doesn't know the clkreq signal 
>> host is
>> not sending refclk. Due to this endpoint is seeing linkdown and going
>> to bad state.
>> To avoid those ref clk should be provided always to the endpoint. The
>> issue is coming only when ep intiates the L1.1 or L1.2 exit and clkreq
>> is not being propagated properly to the host.
> I'm gonna sound like a broken record, but:
>
> How much power does this consume? Would it matter if we kept this
> clock always-on for all platforms with this version of the phy?
>
> Konrad

We see about 22mw extra power consumption with refclk always on.

We can't keep this property always on as there is impact on power 
consumption.

- Krishna Chaitanya