linux-kernel - Re: [PATCH v2 1/2] dt-bindings: clock: Add nvmem-clock

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Message-ID: <92428212-2fe5-a07a-66d1-67b6939c7c9b@linaro.org>
Date:   Fri, 2 Jun 2023 15:19:15 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Mike Looijmans <mike.looijmans@...ic.nl>,
        devicetree@...r.kernel.org, linux-clk@...r.kernel.org
Cc:     Conor Dooley <conor+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] dt-bindings: clock: Add nvmem-clock

Resending as my previous email probably got lost. If you got it twice,
apologies.


On 26/05/2023 16:38, Mike Looijmans wrote:
> Add bindings for a fixed-rate clock that retrieves its rate from an
> NVMEM provider. This allows to store clock settings in EEPROM or EFUSE
> or similar device.
> 
> Component shortages lead to boards being shipped with different clock
> crystals, based on what was available at the time. The clock frequency
> was written to EEPROM at production time. Systems can adapt to a wide
> range of input frequencies using the clock framework, but this required
> us to patch the devicetree at runtime or use some custom driver. This
> provides a more generic solution.

This does not look like real hardware. I mean, the clock does not fetch
its rate from nvmem, right? It's the Linux which does it, so basically
you described here driver, not hardware.

Extend existing fixed-clock bindings to allow reading frequency via
nvmem cells.



Best regards,
Krzysztof