linux-kernel - Re: [PATCH v9 6/6] arm64: dts: qcom: ipq9574: Add icc provider ability to gcc

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Message-ID: <ZmpsOdsl9AMTSH88@hu-varada-blr.qualcomm.com>
Date: Thu, 13 Jun 2024 09:19:13 +0530
From: Varadarajan Narayanan <quic_varada@...cinc.com>
To: Georgi Djakov <djakov@...nel.org>
CC: Konrad Dybcio <konrad.dybcio@...aro.org>,
        Dmitry Baryshkov
	<dmitry.baryshkov@...aro.org>,
        <andersson@...nel.org>, <mturquette@...libre.com>, <sboyd@...nel.org>,
        <robh@...nel.org>, <krzk+dt@...nel.org>, <conor+dt@...nel.org>,
        <quic_anusha@...cinc.com>, <linux-arm-msm@...r.kernel.org>,
        <linux-clk@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v9 6/6] arm64: dts: qcom: ipq9574: Add icc provider
 ability to gcc

On Wed, Jun 12, 2024 at 03:52:51PM +0300, Georgi Djakov wrote:
> On 12.06.24 13:28, Varadarajan Narayanan wrote:
> > On Wed, Jun 12, 2024 at 11:48:17AM +0300, Georgi Djakov wrote:
> > > On 12.06.24 9:30, Varadarajan Narayanan wrote:
> > > > On Tue, Jun 11, 2024 at 02:29:48PM +0300, Georgi Djakov wrote:
> > > > > On 11.06.24 12:42, Varadarajan Narayanan wrote:
> > > > > > On Thu, Jun 06, 2024 at 04:06:01PM +0200, Konrad Dybcio wrote:
> > > > > > > On 8.05.2024 10:10 AM, Dmitry Baryshkov wrote:
> > > > > > > > On Wed, 8 May 2024 at 09:53, Varadarajan Narayanan
> > > > > > > > <quic_varada@...cinc.com> wrote:
> > > > > > > > >
> > > > > > > > > On Fri, May 03, 2024 at 04:51:04PM +0300, Georgi Djakov wrote:
> > > > > > > > > > Hi Varada,
> > > > > > > > > >
> > > > > > > > > > Thank you for your work on this!
> > > > > > > > > >
> > > > > > > > > > On 2.05.24 12:30, Varadarajan Narayanan wrote:
> > > > > > > > > > > On Tue, Apr 30, 2024 at 12:05:29PM +0200, Konrad Dybcio wrote:
> > > > > > > > > > > > On 25.04.2024 12:26 PM, Varadarajan Narayanan wrote:
> > > > > > > > > > > > > On Tue, Apr 23, 2024 at 02:58:41PM +0200, Konrad Dybcio wrote:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > On 4/18/24 11:23, Varadarajan Narayanan wrote:
> > > > > > > > > > > > > > > IPQ SoCs dont involve RPM in managing NoC related clocks and
> > > > > > > > > > > > > > > there is no NoC scaling. Linux itself handles these clocks.
> > > > > > > > > > > > > > > However, these should not be exposed as just clocks and align
> > > > > > > > > > > > > > > with other Qualcomm SoCs that handle these clocks from a
> > > > > > > > > > > > > > > interconnect provider.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Hence include icc provider capability to the gcc node so that
> > > > > > > > > > > > > > > peripherals can use the interconnect facility to enable these
> > > > > > > > > > > > > > > clocks.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > > > > > > > > > > > > > > Signed-off-by: Varadarajan Narayanan <quic_varada@...cinc.com>
> > > > > > > > > > > > > > > ---
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > If this is all you do to enable interconnect (which is not the case,
> > > > > > > > > > > > > > as this patch only satisfies the bindings checker, the meaningful
> > > > > > > > > > > > > > change happens in the previous patch) and nothing explodes, this is
> > > > > > > > > > > > > > an apparent sign of your driver doing nothing.
> > > > > > > > > > > > >
> > > > > > > > > > > > > It appears to do nothing because, we are just enabling the clock
> > > > > > > > > > > > > provider to also act as interconnect provider. Only when the
> > > > > > > > > > > > > consumers are enabled with interconnect usage, this will create
> > > > > > > > > > > > > paths and turn on the relevant NOC clocks.
> > > > > > > > > > > >
> > > > > > > > > > > > No, with sync_state it actually does "something" (sets the interconnect
> > > > > > > > > > > > path bandwidths to zero). And *this* patch does nothing functionally,
> > > > > > > > > > > > it only makes the dt checker happy.
> > > > > > > > > > >
>
> [..]
>
> >
> > nsscc_ipq9574 was not using icc_sync_state. After adding that, I
> > can see the following messages printed from icc_sync_state. I
> > also added a print to confirm if 'p->set(n, n);' is called.
>
> Ok, that's good! So now when all providers are using sync_state, we
> can go back to the initial comment from Konrad. I think you should
> re-check the tests that you did, as the current results just lead to
> more questions than answers. Maybe it was just the sync-state that
> was missing, or there is some other issue.

Georgi,

Thanks very much for the clarifications. Will re-test the patches
and update the thread.

-Varada

> [..]
> >
> > The gcc based interconnect paths are referenced by PCIe controller
> > nodes. Please refer to this patch
> >
> > 	[PATCH V5 4/6] arm64: dts: qcom: ipq9574: Add PCIe PHYs and controller nodes
> > 	https://lore.kernel.org/linux-arm-msm/20240512082858.1806694-5-quic_devipriy@quicinc.com/
> >
> > Sorry, did not post the nsscc related patches since this base ICC
> > patch hasn't reached closure. The nsscc patches are very similar
> > to this gcc based series. Wanted to gather the issues raised in
> > this and address them in nsscc so that it is in a more acceptable
> > shape.
> >
> > Thanks
> > Varada
>