linux-kernel - Re: [PATCH 0/2] clk: qcom: Add support for multiple power-domains for a clock controller.

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Message-ID: <3ce358b9-6a65-4141-ad3a-bbb826082470@linaro.org>
Date: Mon, 18 Nov 2024 13:22:15 +0000
From: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Bjorn Andersson <andersson@...nel.org>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, linux-arm-msm@...r.kernel.org,
 linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] clk: qcom: Add support for multiple power-domains for
 a clock controller.

On 18/11/2024 13:15, Dmitry Baryshkov wrote:
>> On x1e80100 and it's SKUs the Camera Clock Controller - CAMCC has
>> multiple power-domains which power it. Usually with a single power-domain
>> the core platform code will automatically switch on the singleton
>> power-domain for you. If you have multiple power-domains for a device, in
>> this case the clock controller, you need to switch those power-domains
>> on/off yourself.

> I think the series misses the platform-specific part. 

I don't think I understand what you mean by that.

It is hard to
> understand what kind of power relationship do you need to express. Is it
> actually the whole CC being powered by several domains? Or are some of
> those domains used to power up PLLs? Or as parents to some of GDSCs?

Well for example the TITAN_TOP_GDSC needs both PDs to be switched on.

We _could_ do this just for the CAMCC on x1e80100 - i.e. make it just 
for the camcc device but then, the next clock controller that needs more 
than one PD will have to implement the same fix.

---
bod