linux-kernel - Re: [PATCH 2/4] hwrng: stm32 - implement support for STM32MP25x platforms

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Message-ID: <c59f3593-cb69-48c6-ab0e-f1275c7e5477@denx.de>
Date: Fri, 11 Oct 2024 14:38:04 +0200
From: Marek Vasut <marex@...x.de>
To: Gatien CHEVALLIER <gatien.chevallier@...s.st.com>,
 Olivia Mackall <olivia@...enic.com>, Herbert Xu
 <herbert@...dor.apana.org.au>, Rob Herring <robh+dt@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Maxime Coquelin <mcoquelin.stm32@...il.com>,
 Alexandre Torgue <alexandre.torgue@...s.st.com>
Cc: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
 Lionel Debieve <lionel.debieve@...s.st.com>, linux-crypto@...r.kernel.org,
 devicetree@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 Yang Yingliang <yangyingliang@...wei.com>
Subject: Re: [PATCH 2/4] hwrng: stm32 - implement support for STM32MP25x
 platforms

On 10/11/24 2:07 PM, Gatien CHEVALLIER wrote:
> 
> 
> On 10/11/24 13:24, Marek Vasut wrote:
>> On 10/11/24 11:55 AM, Gatien CHEVALLIER wrote:
>>>
>>>
>>> On 10/7/24 15:54, Marek Vasut wrote:
>>>> On 10/7/24 3:27 PM, Gatien Chevallier wrote:
>>>>> Implement the support for STM32MP25x platforms. On this platform, a
>>>>> security clock is shared between some hardware blocks. For the RNG,
>>>>> it is the RNG kernel clock. Therefore, the gate is no more shared
>>>>> between the RNG bus and kernel clocks as on STM32MP1x platforms and
>>>>> the bus clock has to be managed on its own.
>>>>>
>>>>> Signed-off-by: Gatien Chevallier <gatien.chevallier@...s.st.com>
>>>> A bit of a higher-level design question -- can you use drivers/clk/ 
>>>> clk-bulk.c clk_bulk_*() to handle all these disparate count of clock 
>>>> easily ?
>>>
>>> Hi, I'd like to make sure that we enable the core clock before the bus
>>> clock so that the RNG hardware block can start its internal tests while
>>> we ungate the bus clock. It's not a strong opinion but it feels better.
>> Maybe this could still work if the struct clk_bulk_data {} is ordered 
>> that way, so the bus clock are first, and the rest afterward ?
> 
> I guess you meant, the core first.

Err, yes, core.

> Putting the bus clock first with the updated YAML doc generates a
> warning when checking the bindings. I guess what you propose is OK
> then. Core clock is defined first in the device tree.

Not in DT, leave DT as-is. Look at struct clk_bulk_data , I think when 
you use the clk_bulk_*() functions, you pass in a list of struct 
clk_bulk_data, which each describes one clock, so just make sure that 
list of struct clk_bulk_data in the driver is ordered the way you need 
it to be ordered and you should be fine.