Re: [PATCH v2 1/4] dt-bindings: PCI: dwc: rockchip: Add atu property

[Rob Herring <robh@kernel.org>]

On Wed, Oct 25, 2023 at 08:02:32PM +0000, Niklas Cassel wrote:
> Hello Conor,
> 
> On Tue, Oct 24, 2023 at 05:29:28PM +0100, Conor Dooley wrote:
> > On Tue, Oct 24, 2023 at 05:10:08PM +0200, Niklas Cassel wrote:
> > > From: Niklas Cassel <niklas.cassel@wdc.com>
> > > 
> > > Even though rockchip-dw-pcie.yaml inherits snps,dw-pcie.yaml
> > > using:
> > > 
> > > allOf:
> > >   - $ref: /schemas/pci/snps,dw-pcie.yaml#
> > > 
> > > and snps,dw-pcie.yaml does have the atu property defined, in order to be
> > > able to use this property, while still making sure 'make CHECK_DTBS=y'
> > > pass, we need to add this property to rockchip-dw-pcie.yaml.
> > > 
> > > Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
> > > ---
> > >  Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml b/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml
> > > index 1ae8dcfa072c..229f8608c535 100644
> > > --- a/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml
> > > +++ b/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml
> > > @@ -29,16 +29,20 @@ properties:
> > >            - const: rockchip,rk3568-pcie
> > >  
> > >    reg:
> > > +    minItems: 3
> > >      items:
> > >        - description: Data Bus Interface (DBI) registers
> > >        - description: Rockchip designed configuration registers
> > >        - description: Config registers
> > > +      - description: iATU registers
> > 
> > Is this extra register only for the ..88 or for the ..68 and for the
> > ..88 models?
> 
> Looking at the rk3568 Technical Reference Manual (TRM):
> https://dl.radxa.com/rock3/docs/hw/datasheet/Rockchip%20RK3568%20TRM%20Part2%20V1.1-20210301.pdf
> 
> The iATU register register range exists for all 3 PCIe controllers
> found on the rk3568.
> 
> This register range is currently not defined in the rk3568.dtsi, so the driver
> will currently use the default register offset (which is correct), but with
> the driver fallback register size that is only big enough to cover 8 inbound
> and 8 outbound iATUs (internal Address Translation Units).

We should probably make the driver smarter instead or in addition. We 
have the DBI size, Just make atu_size = dbi_size - DEFAULT_DBI_ATU_OFFSET.

> According to the TRM, all three PCIe controllers found on the rk3568 have
> 16 inbound iATUs and 16 outbound iATUs, so if someone wants to be able to
> make use of all the iATUs on the rk3568, they will need to add "atu" to
> rk3568.dtsi.

At least for host side, the number of regions used is based on ranges. 
You'd be hard pressed to need more than 8. That or no h/w with 16 is 
probably why I said 8 was enough at the time.

Rob