linux-kernel - Re: [PATCH v2 04/16] dt-bindings: clock: at91: Allow referencing main rc oscillator in DT

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Message-ID: <71910842-6310-4e1f-81a1-3b218e1ee69a@kernel.org>
Date: Tue, 11 Feb 2025 09:01:49 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Claudiu Beznea <claudiu.beznea@...on.dev>,
 Nicolas Ferre <nicolas.ferre@...rochip.com>,
 Ryan Wanner <ryan.wanner@...rochip.com>,
 linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
 linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>
Subject: Re: [PATCH v2 04/16] dt-bindings: clock: at91: Allow referencing main
 rc oscillator in DT

On 11/02/2025 08:26, Alexander Dahl wrote:
> Hello Krzysztof,
> 
> Am Mon, Feb 10, 2025 at 06:07:10PM +0100 schrieb Krzysztof Kozlowski:
>> On 10/02/2025 17:44, Alexander Dahl wrote:
>>> The main rc oscillator will be needed for the OTPC to work properly.
>>>
>>> The new index introduced here was not used on the four affected SoC
>>> clock drivers before, but for sama5d2 only (PMC_I2S1_MUX).
>>>
>>> Link: https://lore.kernel.org/linux-devicetree/20250207-jailbird-circus-bcc04ee90e05@thorsis.com/T/#u
>>> Signed-off-by: Alexander Dahl <ada@...rsis.com>
>>> ---
>>>
>>> Notes:
>>>     v2:
>>>     - new patch, not present in v1
>>>
>>>  include/dt-bindings/clock/microchip,sam9x60-pmc.h  | 3 +++
>>>  include/dt-bindings/clock/microchip,sam9x7-pmc.h   | 3 +++
>>>  include/dt-bindings/clock/microchip,sama7d65-pmc.h | 3 +++
>>>  include/dt-bindings/clock/microchip,sama7g5-pmc.h  | 3 +++
>>>  4 files changed, 12 insertions(+)
>>>
>>> diff --git a/include/dt-bindings/clock/microchip,sam9x60-pmc.h b/include/dt-bindings/clock/microchip,sam9x60-pmc.h
>>> index e01e867e8c4da..dcd3c74f75b54 100644
>>> --- a/include/dt-bindings/clock/microchip,sam9x60-pmc.h
>>> +++ b/include/dt-bindings/clock/microchip,sam9x60-pmc.h
>>> @@ -16,4 +16,7 @@
>>>  
>>>  #define SAM9X60_PMC_PLLACK	PMC_PLLACK	/* 7 */
>>>  
>>> +/* new from after bindings splitup */
>>> +#define SAM9X60_PMC_MAIN_RC	6
>>
>> This is confusing me, because:
>> 1. You still have holes in IDs
> 
> Yes, I was told to maintain the old values for interface stability in
> series v1 feedback.
> 
>> 2. This should be placed in proper order by ID
> 
> Okay, no problem.
> 
>> 3. Why not using 4 - the next available empty ID?
> 
> The MAIN_RC clock is used on four out of thirteen (?) SoC variants
> which all used the same IDs before.  6 is the first ID which is free
> on all of sam9x60, sam9x7, sama7g5, and sama7d65.  The last two
> already use 4 for a different clock.

So driver for this device already uses something for 4?

> 
> The whole splitup is to avoid even more and/or bigger holes, but is it
> important where the existent holes are filled?
> 
> Technically if the next available empty ID should be used it would be
> 4 for sam9x60 and sam9x7, 2 for sama7d65, and 6 for sama7g5.  I
> thought it would be nice to use the same value instead to make
> somewhat compatible to the old approach.


Best regards,
Krzysztof