linux-kernel - Re: [PATCH v3 06/10] arm64: dts: qcom: sc7280: Update reserved memory map

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Message-ID: <YR/hBYyYuYWN68LV@ripper>
Date:   Fri, 20 Aug 2021 10:06:13 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Sibi Sankar <sibis@...eaurora.org>
Cc:     Vinod Koul <vkoul@...nel.org>, robh+dt@...nel.org, will@...nel.org,
        saiprakash.ranjan@...eaurora.org, swboyd@...omium.org,
        mka@...omium.org, ohad@...ery.com, agross@...nel.org,
        mathieu.poirier@...aro.org, robin.murphy@....com, joro@...tes.org,
        p.zabel@...gutronix.de, linux-arm-msm@...r.kernel.org,
        linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        evgreen@...omium.org, dianders@...omium.org
Subject: Re: [PATCH v3 06/10] arm64: dts: qcom: sc7280: Update reserved
 memory map

On Fri 20 Aug 07:09 PDT 2021, Sibi Sankar wrote:

> On 2021-08-19 10:07, Vinod Koul wrote:
> > Hi Sibi,
> > 
> > On 19-08-21, 09:06, Sibi Sankar wrote:
> > 
> > > diff --git a/arch/arm64/boot/dts/qcom/sc7280.dtsi
> > > b/arch/arm64/boot/dts/qcom/sc7280.dtsi
> > > index 5e4f4f3b738a..894106efadfe 100644
> > > --- a/arch/arm64/boot/dts/qcom/sc7280.dtsi
> > > +++ b/arch/arm64/boot/dts/qcom/sc7280.dtsi
> > > @@ -48,6 +48,16 @@
> > >  		#size-cells = <2>;
> > >  		ranges;
> > > 
> > > +		hyp_mem: memory@...00000 {
> > > +			reg = <0x0 0x80000000 0x0 0x600000>;
> > > +			no-map;
> > 
> > This should conflict with the memory defined in this file:
> > 
> >         memory@...00000 {
> >                 device_type = "memory";
> >                 /* We expect the bootloader to fill in the size */
> >                 reg = <0 0x80000000 0 0>;
> >         };
> > 
> > I think this should be updated?
> 
> Vinod,
> 
> I prefer we leave ^^ node untouched.  For platforms using hyp_mem, the
> regions defined in the memory map are valid and for the other
> platforms not using hyp_mem we would just delete them in the board
> files anyway.

Logically this node describes where there is RAM, the reserved-memory
then subtracts blocks of memory out of that. So I think it's perfectly
legal for a region at the base to be marked as no-map.

That said, isn't the address in the memory node just a placeholder?

Regards,
Bjorn