linux-kernel - Re: [PATCH v3 09/19] dt-bindings: nvmem: microchip-otpc: Add required clocks

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Message-ID: <b9de4cf4-c4b8-4f5e-9cd7-16991bda439b@tuxon.dev>
Date: Sat, 31 Jan 2026 17:51:24 +0200
From: Claudiu Beznea <claudiu.beznea@...on.dev>
To: Alexander Dahl <ada@...rsis.com>
Cc: Nicolas Ferre <nicolas.ferre@...rochip.com>,
 Alexandre Belloni <alexandre.belloni@...tlin.com>,
 Ryan Wanner <ryan.wanner@...rochip.com>,
 linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
 Srinivas Kandagatla <srini@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>
Subject: Re: [PATCH v3 09/19] dt-bindings: nvmem: microchip-otpc: Add required
 clocks



On 1/31/26 17:47, Claudiu Beznea wrote:
> 
> 
> On 1/20/26 17:44, Alexander Dahl wrote:
>> The OTPC requires both the peripheral clock through PMC and the main RC
>> oscillator.  Seemed to work without explicitly enabling those clocks on
>> sama7g5 before, but did not on sam9x60.
>>
>> Older datasheets were not clear and explicit about this, but recent are,
>> e.g. SAMA7G5 series datasheet (DS60001765B),
>> section 30.4.1 Power Management:
>>
>>> The OTPC is clocked through the Power Management Controller (PMC).
>>> The user must power on the main RC oscillator and enable the
>>> peripheral clock of the OTPC prior to reading or writing the OTP
>>> memory.
> 
> As this was not mentioned in the previous datasheet versions, the current driver 
> don't handle those clocks, and it probably worked as the clocks were enabled by 
> bootloaders, I think the clocks should be marked as required and this patch to 
> be propagated as a fix along with fixes on driver and device trees.

Ah, wait, you can't propagate it as a fix as you don't have the necessary clocks 
exported in device tree in the older kernels. And you are just handling it in 
this series.

> 
> I'll let DT binding maintainers for the final decision on this.
> 
>>
>> Link: https://lore.kernel.org/linux-clk/ec34efc2-2051-4b8a- 
>> b5d8-6e2fd5e08c28@...rochip.com/T/#u
> 
> Why this link here?
> 
>> Signed-off-by: Alexander Dahl <ada@...rsis.com>
>> ---
>>
>> Notes:
>>      v3:
>>      - Removed clock-names (led to confusion, and not used by the driver anyways)
>>      - Removed redundant example
>>      v2:
>>      - new patch, not present in v1
>>
>>   .../devicetree/bindings/nvmem/microchip,sama7g5-otpc.yaml | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/nvmem/microchip,sama7g5- 
>> otpc.yaml b/Documentation/devicetree/bindings/nvmem/microchip,sama7g5-otpc.yaml
>> index 9a7aaf64eef32..847dfb67c6b72 100644
>> --- a/Documentation/devicetree/bindings/nvmem/microchip,sama7g5-otpc.yaml
>> +++ b/Documentation/devicetree/bindings/nvmem/microchip,sama7g5-otpc.yaml
>> @@ -29,6 +29,11 @@ properties:
>>     reg:
>>       maxItems: 1
>> +  clocks:
>> +    items:
>> +      - description: main rc oscillator
>> +      - description: otpc peripheral clock
>> +
>>   required:
>>     - compatible
>>     - reg
>> @@ -37,6 +42,8 @@ unevaluatedProperties: false
>>   examples:
>>     - |
>> +    #include <dt-bindings/clock/at91.h>
>> +    #include <dt-bindings/clock/microchip,sama7g5-pmc.h>
>>       #include <dt-bindings/nvmem/microchip,sama7g5-otpc.h>
>>       otpc: efuse@...00000 {
>> @@ -44,6 +51,7 @@ examples:
>>           reg = <0xe8c00000 0xec>;
>>           #address-cells = <1>;
>>           #size-cells = <1>;
>> +        clocks = <&pmc PMC_TYPE_CORE SAMA7G5_PMC_MAIN_RC>, <&pmc 
>> PMC_TYPE_PERIPHERAL 67>;
>>           temperature_calib: calib@1 {
>>               reg = <OTP_PKT(1) 76>;
>