linux-kernel - Re: [PATCH 2/3] regulator: qcom

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Date:   Wed, 22 May 2019 08:58:11 -0600
From:   Jeffrey Hugo <jhugo@...eaurora.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     Jeffrey Hugo <jeffrey.l.hugo@...il.com>, lgirdwood@...il.com,
        agross@...nel.org, david.brown@...aro.org,
        bjorn.andersson@...aro.org, jcrouse@...eaurora.org,
        robh+dt@...nel.org, mark.rutland@....com,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org,
        Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@...aro.org>
Subject: Re: [PATCH 2/3] regulator: qcom_spmi: Add support for PM8005

On 5/22/2019 8:28 AM, Mark Brown wrote:
> On Wed, May 22, 2019 at 08:16:38AM -0600, Jeffrey Hugo wrote:
>> On 5/22/2019 5:01 AM, Mark Brown wrote:
>>> On Tue, May 21, 2019 at 05:16:06PM -0600, Jeffrey Hugo wrote:
> 
>>>> I'm open to suggestions.  Apparently there are two register common register
>>>> schemes - the old one and the new one.  PMIC designs after some random point
>>>> in time are all the new register scheme per the documentation I see.
> 
>>>> As far as I an aware, the FT426 design is the first design to be added to
>>>> this driver to make use of the new scheme, but I expect more to be supported
>>>> in future, thus I'm reluctant to make these ft426 specific in the name.
> 
>>> If there's a completely new register map why are these even in the same
>>> driver?
> 
>> Its not completely new, its a derivative of the old scheme.  Of the 104
>> registers, approximately 5 have been modified, therefore the new scheme is
>> 95% compatible with the old one.  Duplicating a 1883 line driver to handle a
>> change in 5% of the register space seems less than ideal. Particularly
>> considering your previous comments seem to indicate that you feel its pretty
>> trivial to handle the quirks associated with the changes in this driver.
> 
> Ah, so it's not a completely new scheme but rather just a couple of
> registers that have changed.  Sharing the driver is fine then.  Ideally
> there would be some documentation from the vendor about this, a mention
> of IP revisions or some such.  If not what the DT bindings do for names
> is use the first chip things were found in.
> 

The documentation isn't great.  There isn't really an IP revision this 
started with.  Looking at all of the PMIC designs, this actually started 
with PM8005, so I guess "common2" becomes "pm8005", and the PMS405 
should reuse that.  I'll coordinate with Jorge.

-- 
Jeffrey Hugo
Qualcomm Datacenter Technologies as an affiliate of Qualcomm 
Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.