linux-kernel - Re: [PATCH v4 13/14] gunyah: rsc_mgr: Add auxiliary devices for console

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Message-ID: <Yz51kCQmMUtpiEKt@kroah.com>
Date:   Thu, 6 Oct 2022 08:28:32 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Elliot Berman <quic_eberman@...cinc.com>
Cc:     Bjorn Andersson <quic_bjorande@...cinc.com>,
        Murali Nalajala <quic_mnalajal@...cinc.com>,
        Trilok Soni <quic_tsoni@...cinc.com>,
        Srivatsa Vaddagiri <quic_svaddagi@...cinc.com>,
        Carl van Schaik <quic_cvanscha@...cinc.com>,
        Andy Gross <agross@...nel.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Jassi Brar <jassisinghbrar@...il.com>,
        linux-arm-kernel@...ts.infradead.org,
        Mark Rutland <mark.rutland@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Jonathan Corbet <corbet@....net>,
        Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Arnd Bergmann <arnd@...db.de>, devicetree@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 13/14] gunyah: rsc_mgr: Add auxiliary devices for
 console

On Wed, Oct 05, 2022 at 02:47:46PM -0700, Elliot Berman wrote:
> 
> 
> On 10/4/2022 11:21 PM, Greg Kroah-Hartman wrote:
> > On Tue, Oct 04, 2022 at 04:49:27PM -0700, Elliot Berman wrote:
> > > On 9/30/2022 5:19 AM, Greg Kroah-Hartman wrote:
> > > > On Wed, Sep 28, 2022 at 12:56:32PM -0700, Elliot Berman wrote:
> > > > > Gunyah resource manager exposes a concrete functionalities which
> > > > > complicate a single resource manager driver.
> > > > 
> > > > I am sorry, but I do not understand this sentance.  What is so
> > > > complicated about individual devices being created?  Where are they
> > > > created?  What bus?
> > > 
> > > There's no complexity here with using individual devices, that's why I
> > > wanted to create secondary (auxiliary devices).
> > > 
> > > IOW -- "I have a platform device that does a lot of different things. Split
> > > up the different functionalities of that device into sub devices using the
> > > auxiliary bus."
> > 
> > Why not just have multiple platform devices?  You control them, don't
> > make it more complex than it should be.
> > 
> > And why are these platform devices at all?
> > 
> > As you say:
> > 
> > > A key requirement for utilizing the auxiliary bus is that there is no
> > > dependency on a physical bus, device, register accesses or regmap support.
> > > These individual devices split from the core cannot live on the platform bus
> > > as they are not physical devices that are controlled by DT/ACPI.
> > 
> > These are not in the DT.  So just make your own bus for them instead of
> > using a platform device.  Don't abuse a platform device please.
> > 
> 
> I'll avoid creating platform devices. Are there any concerns with creating
> auxiliary device under the platform device?

Yes, don't do it if you do not have to, auxiliary devices are there only
if you have no other choice.

Just make 2 real devices on your own virtual bus please.

thanks,

greg k-h