linux-kernel - Re: [PATCH v1 3/3] arm64: dts: qcom: ipq5332: Add icc provider ability to gcc

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Message-ID: <a4deabfa-1366-47ef-993f-2fae3e206a44@linaro.org>
Date: Wed, 10 Jul 2024 12:49:13 +0200
From: Konrad Dybcio <konrad.dybcio@...aro.org>
To: Varadarajan Narayanan <quic_varada@...cinc.com>
Cc: andersson@...nel.org, mturquette@...libre.com, sboyd@...nel.org,
 robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, djakov@...nel.org,
 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 v1 3/3] arm64: dts: qcom: ipq5332: Add icc provider
 ability to gcc

On 10.07.2024 12:42 PM, Varadarajan Narayanan wrote:
> On Tue, Jul 09, 2024 at 11:53:41AM +0200, Konrad Dybcio wrote:
>> On 9.07.2024 8:39 AM, 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.
>>>
>>> Signed-off-by: Varadarajan Narayanan <quic_varada@...cinc.com>
>>> ---
>>
>> Doesn't the USB host need to have its path described to keep working?
> 
> Presently, USB host enables GCC_SNOC_USB_CLK directly using
> the clocks/clock-name entries. So it is not dependent on ICC.
> 
> Shall I update the USB DT node to use interconnects now itself,
> or wait until this IPQ5332 ICC enablement series is approved?
> Please let me know.

Definitely so. Now that you registered that clock with the
interconnect framework, the current usage is essentially
circumventing it..

Say some consumers casted an ICC vote on that node, and then
the USB driver called set_rate on the clock.. The data from
icc-clk would be discarded

Konrad