linux-kernel - Re: [PATCH 2/2] Documentation: cs35l41: Shared boost properties

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Date:   Wed, 8 Feb 2023 11:23:56 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     lucas.tanure@...labora.com, David Rhodes <david.rhodes@...rus.com>,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        devicetree@...r.kernel.org, patches@...nsource.cirrus.com,
        linux-kernel@...r.kernel.org, kernel@...labora.com
Subject: Re: [PATCH 2/2] Documentation: cs35l41: Shared boost properties

On 07/02/2023 18:03, lucas.tanure@...labora.com wrote:
> On 2/7/23 4:48 PM, Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org> wrote:
>> On 07/02/2023 17:34, Lucas Tanure wrote:
>>> On 07-02-2023 16:13, Krzysztof Kozlowski wrote:
>>>> On 07/02/2023 16:46, Lucas Tanure wrote:
>>>>>>> +      Shared boost allows two amplifiers to share a single boost circuit by
>>>>>>> +      communicating on the MDSYNC bus. The passive amplifier does not control
>>>>>>> +      the boost and receives data from the active amplifier. GPIO1 should be
>>>>>>> +      configured for Sync when shared boost is used. Shared boost is not
>>>>>>> +      compatible with External boost. Active amplifier requires
>>>>>>> +      boost-peak-milliamp, boost-ind-nanohenry and boost-cap-microfarad.
>>>>>>>           0 = Internal Boost
>>>>>>>           1 = External Boost
>>>>>>> +      2 = Reserved
>>>>>>
>>>>>> How binding can be reserved? For what and why? Drop. 2 is shared active,
>>>>>> 3 is shared passive.
>>>>> 2 Is shared boost without VSPK switch, a mode not supported for new
>>>>> system designs. But there is laptops using it, so we need to keep
>>>>> supporting in the driver.
>>>>
>>>> That's not the answer. 2 is nothing here, so it cannot be reserved.
>>>> Aren't you mixing now some register value with bindings?
>>>>
>>>> Best regards,
>>>> Krzysztof
>>>>
>>>>
>>> I have added a new patch with propper documentation.
>>> And I would like to use 3 and 4 for shared boost as
>>> CS35L41_EXT_BOOST_NO_VSPK_SWITCH already exist as 2 and is used in the
>>> current driver.
>>
>> I don't see CS35L41_EXT_BOOST_NO_VSPK_SWITCH in the bindings.
>>
>>> The laptop that uses CS35L41_EXT_BOOST_NO_VSPK_SWITCH doesn't have the
>>> property "cirrus,boost-type", but to make everything consistent I would
>>> prefer to use 3 and 4 for the new boost types.
>>> Is that ok with you?
>>
>> I don't see how it is related. The value does not exist, so whether
>> laptop has that property or not, is not really related, right?
>>
>> Best regards,
>> Krzysztof
>>
>>
> The value does exist in the code, but no device should have that in ACPI/DTB, so yes the value doesn't exist for ACPI/DTB purposes.
> I can change CS35L41_EXT_BOOST_NO_VSPK_SWITCH to another value, like 99, and use 2 and 3 for shared boost.
> I will re-submit that with v3.
> Is that ok with you?

I guess we still talk about different things. The code does not have a
binding for the boost, therefore it does not use boost binding. Whatever
it does with CS35L41_EXT_BOOST_NO_VSPK_SWITCH outside of DT, is not my
topic and I don't care.

That's why I asked folks to use strings for such enumerations, not
register values - to avoid any confusion between the code and bindings
(and also make it more readable for humans).

Best regards,
Krzysztof