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

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Message-ID: <e8aa571a-2d96-47da-34f0-47cc048dc655@collabora.com>
Date:   Tue, 7 Feb 2023 17:03:31 +0000
From:   lucas.tanure@...labora.com
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        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 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?

Thanks
Lucas