linux-kernel - Re: [PATCH v2 3/4] arm64: dts: exynos: gs101: add ACPM protocol node

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Message-ID: <4e8936e0-ac69-49e8-919f-b2776dd88779@linaro.org>
Date: Tue, 17 Dec 2024 08:38:29 +0000
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: William McVicker <willmcvicker@...gle.com>
Cc: Peter Griffin <peter.griffin@...aro.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Alim Akhtar <alim.akhtar@...sung.com>,
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
 linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 andre.draszik@...aro.org, kernel-team@...roid.com,
 daniel.lezcano@...aro.org, vincent.guittot@...aro.org,
 ulf.hansson@...aro.org, arnd@...db.de
Subject: Re: [PATCH v2 3/4] arm64: dts: exynos: gs101: add ACPM protocol node



On 12/17/24 7:20 AM, Tudor Ambarus wrote:
> 
> 
> On 12/16/24 6:54 PM, William McVicker wrote:
>> Hi Tudor,
> 
> Hi, William!
> 
>>
>> On 12/12/2024, Tudor Ambarus wrote:
>>> Add the ACPM protocol node. ACPM protocol provides interface for all
>>> the client drivers making use of the features offered by the
>>> Active Power Management (APM) module.
>>>
>>> Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>
>>> ---
>>>  arch/arm64/boot/dts/exynos/google/gs101.dtsi | 22 ++++++++++++++++++++++
>>>  1 file changed, 22 insertions(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/exynos/google/gs101.dtsi b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
>>> index 04561e15b96c..8c3f07371912 100644
>>> --- a/arch/arm64/boot/dts/exynos/google/gs101.dtsi
>>> +++ b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
>>> @@ -277,6 +277,28 @@ apm_sram: sram@...9000 {
>>>  		ranges = <0x0 0x0 0x2039000 0x40000>;
>>>  	};
>>>  
>>> +	firmware {
>>> +		acpm_ipc: power-management {
>>> +			compatible = "google,gs101-acpm-ipc";
>>> +			mboxes = <&ap2apm_mailbox 0 0
>>> +				  &ap2apm_mailbox 0 1
>>> +				  &ap2apm_mailbox 0 2
>>> +				  &ap2apm_mailbox 0 3
>>> +				  &ap2apm_mailbox 0 4
>>> +				  &ap2apm_mailbox 0 5
>>> +				  &ap2apm_mailbox 0 6
>>> +				  &ap2apm_mailbox 0 7
>>> +				  &ap2apm_mailbox 0 8
>>> +				  &ap2apm_mailbox 0 9
>>> +				  &ap2apm_mailbox 0 10
>>> +				  &ap2apm_mailbox 0 11
>>> +				  &ap2apm_mailbox 0 12
>>> +				  &ap2apm_mailbox 0 13
>>> +				  &ap2apm_mailbox 0 14>;
>>> +			shmem = <&apm_sram>;
>>> +		};
>>> +	};
>>
>> You mentioned in the previous patch that "GS101 has 14 mailbox controllers",
> 
> Right, I got the number from the GS101 memory map.
> 
>> but here you have 15 mailboxes. I looked at the downstream driver and see the
> 
> Here we have a single mailbox controller, ap2apm_mailbox, with 15 channels.
> 
>> number of mailboxes is defined by the ACPM framework (firmware) which is read
> 
> s/mailboxes/mailbox channels that ACPM uses/
> 
>> from SRAM initdata. Dumping that, I see there are 15 ACPM channels. Have you
> 
> Correct.
> 
>> looked into into extracting the data from the initdata SRAM address?
>>
> 
> Yes, that's the reason why I defined the 15 channels from above for the
> ap2apm_mailbox controller.
> 

Haven't explicitly mentioned in the commit message: the ACPM protocol is
a mailbox client for the ap2apm_mailbox controller. The ACPM protocol
uses 15 mailbox channels of a total of 16 channels that ap2apm_mailbox
controller provides.

Let me know if you think I shall update the commit message.
Thanks,
ta