linux-kernel - Re: [EXTERNAL] Re: [PATCH RESEND v4 1/4] dt-bindings: platform: microsoft: Document surface xbl

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Message-ID: <Ygu7HdrLnzFj3BrV@yoga>
Date:   Tue, 15 Feb 2022 08:39:25 -0600
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Jarrett Schultz <jaschultz@...rosoft.com>
Cc:     Rob Herring <robh@...nel.org>,
        Jarrett Schultz <jaschultzms@...il.com>,
        Andy Gross <agross@...nel.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <markgross@...nel.org>,
        Maximilian Luz <luzmaximilian@...il.com>,
        Felipe Balbi <balbi@...nel.org>,
        "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [EXTERNAL] Re: [PATCH RESEND v4 1/4] dt-bindings: platform:
 microsoft: Document surface xbl

On Mon 14 Feb 19:04 CST 2022, Jarrett Schultz wrote:

> Jarrett Schultz wrote:
> > From: Jarrett Schultz
> > 
> > Rob Herring wrote:
> > > From: Rob Herring <robh@...nel.org>
> > >
> > > On Tue, Dec 21, 2021 at 10:28:23AM -0800, Jarrett Schultz wrote:
> > > > From: Jarrett Schultz <jaschultz@...rosoft.com>
> > > >
> > > > +title: Surface Extensible Bootloader for Microsoft Surface Duo
> > > > +
> > > > +maintainers:
> > > > +  - Jarrett Schultz <jaschultz@...rosoft.com>
> > > > +
> > > > +description: |
> > > > +  Defined to expose information that is used during production when
> > > > +  device is in manufacturing mode. Some of the information included
> > > > +  in this imem section is -
> > >
> > > If this is onchip sram, we have a binding for that. That's not an MFD.
> > 
> > I now have this driver working with nvmem, but I could not find the binding
> > that you are talking about here. Could you point me to the binding?
> > 
> > Thanks,
> > Jarrett
> > 
> 
> Rob,
> 
> I followed up with my team members who have let me know that this lies
> in DDR rather than SRAM. Could you please point me to the correct
> binding to use?
> 

It might be DDR, but it's on-chip and the memory region that you
describe is a region within "imem" - something used for various purposes
by Qualcomm, presumably also in your device. Unfortunately we haven't
specified a binding for "imem", only some of its regions.

Perhaps it would be appropriate to express the entire imem as nvmem, in
addition to the region-specific logic, if that suits you.

Regards,
Bjorn

> Thanks,
> Jarrett
> 
> > >
> > > > +    * board_id
> > > > +    * battery_present
> > > > +    * hw_init_retries
> > > > +    * is_customer_mode
> > > > +    * is_act_mode
> > > > +    * pmic_reset_reason
> > > > +    * touch_fw_version
> > > > +    * ocp_error_location
> > >
> > > nvmem binding doesn't work for describing these fields?
> > >
> > > > +  See sysfs documentation for more information.
> > >
> > > sysfs? Not relevant to the binding.
> > >
> > > > +
> > > > +properties:
> > > > +  compatible:
> > > > +    const: simple-mfd
> > > > +
> > > > +  reg:
> > > > +    maxItems: 1
> > > > +
> > > > +additionalProperties: false
> > > > +
> > > > +required:
> > > > +  - compatible
> > > > +  - reg
> > > > +  - ranges
> > > > +  - address-cells
> > > > +  - size-cells
> > > > +
> > > > +examples:
> > > > +  - |
> > > > +    / {
> > > > +        compatible = "foo";
> > > > +        model = "foo";
> > >
> > > No need to make this the root node with a fake compatible.
> > >
> > > > +        #address-cells = <2>;
> > > > +        #size-cells = <2>;
> > > > +
> > > > +        imem@...bf000 {
> > > > +          compatible = "simple-mfd";
> > > > +          reg = <0x0 0x146bf000 0x0 0x1000>;
> > > > +          ranges = <0x0 0x0 0x146bf000 0x1000>;
> > > > +          #address-cells = <1>;
> > > > +          #size-cells = <1>;
> > > > +          status = "okay";
> > >
> > > Don't show status in examples.
> > >
> > > > +
> > > > +          xbl@a94 {
> > > > +            compatible = "microsoft,sm8150-surface-duo-xbl";
> > > > +            reg = <0xa94 0x100>;
> > > > +            status = "okay";
> > > > +          };
> > > > +        };
> > > > +      };
> > > > diff --git a/MAINTAINERS b/MAINTAINERS index
> > > > 13f9a84a617e..5d0ca2a98b57 100644
> > > > --- a/MAINTAINERS
> > > > +++ b/MAINTAINERS
> > > > @@ -12649,6 +12649,13 @@ F:	Documentation/driver-
> > > api/surface_aggregator/clients/dtx.rst
> > > >  F:	drivers/platform/surface/surface_dtx.c
> > > >  F:	include/uapi/linux/surface_aggregator/dtx.h
> > > >
> > > > +MICROSOFT SURFACE DUO XBL DRIVER
> > > > +M:	Jarrett Schultz <jaschultz@...rosoft.com>
> > > > +L:	linux-arm-msm@...r.kernel.org
> > > > +L:	platform-driver-x86@...r.kernel.org
> > > > +S:	Supported
> > > > +F:	Documentation/devicetree/bindings/platform/microsoft/surface-
> > > xbl.yaml
> > > > +
> > > >  MICROSOFT SURFACE GPE LID SUPPORT DRIVER
> > > >  M:	Maximilian Luz <luzmaximilian@...il.com>
> > > >  L:	platform-driver-x86@...r.kernel.org
> > > > --
> > > > 2.25.1
> > > >
> > > >