Re: [PATCH 1/3] arm64: dts: qcom: sc7280: Increase config size to 256MB for ECAM feature

[Bjorn Helgaas <helgaas@kernel.org>]

On Thu, Dec 05, 2024 at 05:11:25PM +0100, Konrad Dybcio wrote:
> On 16.11.2024 11:00 PM, Krishna chaitanya chundru wrote:
> > Increase the configuration size to 256MB as required by the ECAM feature.
> > And also move config space, DBI, ELBI, IATU to upper PCIe region and use
> > lower PCIe region entierly for BAR region.
> > 
> > Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
> > ---
> >  arch/arm64/boot/dts/qcom/sc7280.dtsi | 12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> > 
> > diff --git a/arch/arm64/boot/dts/qcom/sc7280.dtsi b/arch/arm64/boot/dts/qcom/sc7280.dtsi
> > index 3d8410683402..a7e3d3e9d034 100644
> > --- a/arch/arm64/boot/dts/qcom/sc7280.dtsi
> > +++ b/arch/arm64/boot/dts/qcom/sc7280.dtsi
> > @@ -2196,10 +2196,10 @@ wifi: wifi@17a10040 {
> >  		pcie1: pcie@1c08000 {
> >  			compatible = "qcom,pcie-sc7280";
> >  			reg = <0 0x01c08000 0 0x3000>,
> > -			      <0 0x40000000 0 0xf1d>,
> > -			      <0 0x40000f20 0 0xa8>,
> > -			      <0 0x40001000 0 0x1000>,
> > -			      <0 0x40100000 0 0x100000>;
> > +			      <4 0x00000000 0 0xf1d>,
> > +			      <4 0x00000f20 0 0xa8>,
> > +			      <4 0x10000000 0 0x1000>,
> > +			      <4 0x00000000 0 0x10000000>;
> 
> So this region is far bigger, any reason to use 256MiB specifically?

I assume this is because ECAM takes 1MB/bus, and pcie1 has
bus-range = <0x00 0xff>.  If one wanted a smaller ECAM area,
I assume one would limit bus-range to match.

Bjorn