linux-kernel - Re: [PATCH] clk: qcom: gcc-ipq6018: add QUP6 I2C clock

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Date:   Thu, 19 Oct 2023 16:23:26 +0200
From:   Robert Marko <robimarko@...il.com>
To:     Kathiravan Thirumoorthy <quic_kathirav@...cinc.com>
Cc:     Konrad Dybcio <konrad.dybcio@...aro.org>, agross@...nel.org,
        andersson@...nel.org, mturquette@...libre.com, sboyd@...nel.org,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: qcom: gcc-ipq6018: add QUP6 I2C clock

On Thu, 19 Oct 2023 at 08:46, Kathiravan Thirumoorthy
<quic_kathirav@...cinc.com> wrote:
>
>
> On 10/19/2023 1:59 AM, Konrad Dybcio wrote:
> >
> >
> > On 10/15/23 18:20, Robert Marko wrote:
> >> QUP6 I2C clock is listed in the dt bindings but it was never included in
> >> the GCC driver.
> >> So lets add support for it, its intentionally marked to never be
> >> disabled
> >> as its somehow affecting DVFS and if disabled it sometimes crashes the
> >> board.
> >>
> >> Signed-off-by: Robert Marko <robimarko@...il.com>
> >> ---
> > Bjorn, would you be able to get an idea of what could be sitting
> > on that bus?
> >
> > Or maybe the IPQ folks could know?
> >
>
> Konrad / Robert,
>
> Similar to IPQ9574, RPM needs this clock to communicate with PMIC over
> I2C interface. Discussion happened here[1] is pretty much applicable to
> IPQ6018 as well. Based on previous experience, we may need to document
> the reason for CLK_IGNORE_UNUSED in driver as well. Nevertheless,
>
> Reviewed-by: Kathiravan Thirumoorthy <quic_kathirav@...cinc.com>

Thanks for the explanation, it makes sense as I used to control the
MP5496 directly
via I2C.

Is it possible to disable RPM so it doesn't conflict and just use the
full MP5496 driver instead?
I find the RPM quite limiting as there is no way to actually retrieve
the current-voltage.

Regards,
Robert
>
> [1]
> https://lore.kernel.org/linux-arm-msm/2852fc37-284f-6534-f163-45b37b153db1@quicinc.com/
>
>
> > Konrad