Message-ID: <f4a545c3-ef1f-39f0-25fd-d9563a950ce2@linaro.org>
Date:   Thu, 2 Feb 2023 21:11:23 +0100
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Subject: Re: [PATCH v4 1/2] dt-bindings: leds-lp55xx: add ti,charge-pump-mode
To:     Maarten Zanders <maarten.zanders@mind.be>,
        Pavel Machek <pavel@ucw.cz>, Lee Jones <lee@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc:     linux-leds@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20230202101032.26737-1-maarten.zanders@mind.be>
 <20230202101032.26737-2-maarten.zanders@mind.be>
 <20eb5589-8287-90bd-3703-2818b61c6ba3@linaro.org>
 <b9c6c74b-65d2-46bf-bd7c-e031d420f31c@mind.be>
 <5fbb6d80-7280-604a-3e1e-4bd98e9776cd@linaro.org>
 <fa47912f-ec10-f22b-0447-0b7c998711b3@mind.be>
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From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <fa47912f-ec10-f22b-0447-0b7c998711b3@mind.be>
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On 02/02/2023 15:12, Maarten Zanders wrote:
> 
> On 2/2/23 14:43, Krzysztof Kozlowski wrote:
>>
>> Strings in DTS are usually easier to for humans to read, but it's not a
>> requirement to use them. The problem of storing register values is that
>> binding is tied/coupled with hardware programming model, so you cannot
>> add a new device if the register value is a bit different (e.g.
>> LP55XX_CP_OFF is 0x1). You need entire new binding for such case. With
>> string - no need.
> I understand and this is why I started with the string in the first 
> place (as suggested by yourself in V1).
>> With binding constants (IDs) also no need, so was this
>> the intention? Just to be clear - it is then ID or binding constant, not
>> a value for hardware register.
>>
> For simplicity sake, yes, now the setting is propagating directly into 
> the register as a bit value. But this is how the current implementation 
> of the drivers work. If we add a device in the future which indeed has 
> different bit mappings, that driver will have to do a mapping of the DT 
> binding to its own bit field definitions. I consider this DT binding as 
> the "master", which is now conveniently chosen to match the register values.

OK, that makes sense.

Best regards,
Krzysztof