linux-kernel - Re: [PATCH v3 2/4] arm64: dts: exynos: gs101: add AP to APM mailbox node

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Message-ID: <d852b956-b61a-4770-8d93-9987a982080d@linaro.org>
Date: Mon, 30 Dec 2024 09:33:49 +0000
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: Krzysztof Kozlowski <krzk@...nel.org>,
 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>,
 Jassi Brar <jassisinghbrar@...il.com>
Cc: 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, willmcvicker@...gle.com,
 daniel.lezcano@...aro.org, vincent.guittot@...aro.org,
 ulf.hansson@...aro.org, arnd@...db.de
Subject: Re: [PATCH v3 2/4] arm64: dts: exynos: gs101: add AP to APM mailbox
 node



On 12/22/24 11:47 AM, Krzysztof Kozlowski wrote:
> On 20/12/2024 15:45, Tudor Ambarus wrote:
>> GS101 has 14 mailbox controllers. Add the AP to APM mailbox node.
>>
>> Mailbox controllers have a shared register that can be used for passing
>> the mailbox messages. The AP to APM mailbox controller is used just as a
>> doorbell mechanism. It raises interrupt to the firmware after the mailbox
>> message has been written to SRAM where the TX/RX rings are defined.
>>
>> Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>
>> ---
>>  arch/arm64/boot/dts/exynos/google/gs101.dtsi | 9 +++++++++
>>  1 file changed, 9 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/exynos/google/gs101.dtsi b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
>> index 1441e9a252c2..6947dd081a0e 100644
>> --- a/arch/arm64/boot/dts/exynos/google/gs101.dtsi
>> +++ b/arch/arm64/boot/dts/exynos/google/gs101.dtsi
>> @@ -1445,6 +1445,15 @@ wakeup-interrupt-controller {
>>  			};
>>  		};
>>  
>> +		ap2apm_mailbox: mailbox@...10000 {
>> +			compatible = "google,gs101-mbox";
> 
> 
> I don't think I have this in my tree and cover letter does not explain
> where I can find bindings. Nothing in next from few days ago. Always
> document in DTS patchset where are the bindings, unless it's obvious.
> 

Noted, will add such details. For the reference the bindings are part of
these patch sets:
https://lore.kernel.org/linux-arm-kernel/20241220-acpm-v4-upstream-mbox-v6-0-a6942806e52a@linaro.org/
https://lore.kernel.org/linux-arm-kernel/20241220-gs101-acpm-v5-0-4f26b7fb3f5f@linaro.org/

I'll ping you once we all have an agreement on the bindings. I'm still
waiting for Jassi to let me know if he's fine with dropping the channel
type argument for the ACPM use case or not. ACPM always uses the mailbox
channel in DOORBELL mode, but this info can't be retrieved from SRAM at
runtime. Jassi suggested that I shall pass the channel type via DT.
While I don't mind, I don't find this necessary. Discussion at:
https://lore.kernel.org/linux-arm-kernel/eaab647a-f6f4-4562-89fa-e64daa80bdf4@linaro.org/

Thanks!
ta