Re: [PATCH 1/5] arm64: dts: qcom: qcs6490-rb3gen2: use pci for device nodes

[Alex Elder <elder@riscstar.com>]

On 9/1/26 3:05 PM, Rob Herring wrote:
> On Tue, Sep 1, 2026 at 12:21 PM Alex Elder <elder@riscstar.com> wrote:
>>
>> A recent change caused the embedded PCIe endpoints on TC9564 SoCs to
>> be treated by the devicetree code as PCI buses, which is incorrect.
>>
>> An RB3gen2 system has an "interposer board" that contains a TC9564
>> SoC.  The TC9564 includes a PCIe switch with one upstream port and
>> two downstream (external) ports, plus a third downstream port.  The
>> third port has an embedded PCIe endpoint with two functions, each
>> providing access to a 10 Gbps capable Ethernet interface.
>>
>> The devicetree nodes representing these functions were previously
>> named "pci@" but were renamed in the interest of consistency in
>> commit e806c63ba51a7 ("arm64: dts: qcom: Rename pci@ nodes to pcie@").
>>
>> Unfortunately, of_node_is_pcie() causes nodes named "pcie@" to be
>> treated as PCI bridges, which PCI endpoints are not.  The previous
>> name "pci" matched such nodes as "default-flags" bus type, defined
>> in the of_busses[] array.
>>
>> Rename the PCIe endpoint nodes "pci@" so they are not mistaken for
>> bridge nodes by the devicetree parsing code.  This restores the
>> previous behavior, and allows them to be used for PCI endpoint bus.
>>
>> Fixes: e806c63ba51a7 ("arm64: dts: qcom: Rename pci@ nodes to pcie@")
>> Signed-off-by: Alex Elder <elder@riscstar.com>
>> ---
>>   arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts b/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts
>> index a13315bf0fb07..99a985a177a61 100644
>> --- a/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts
>> +++ b/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts
>> @@ -954,7 +954,7 @@ pcie@3,0 {
>>                          ranges;
>>                          bus-range = <0x5 0xff>;
>>
>> -                       pcie@0,0 {
>> +                       pci@0,0 {
> 
> The kernel should treat either name the same. There may have been some
> reason 'pci' was not included in checks. It could have been that only
> old things are (parallel, plain) 'pci' and anything new is 'pcie'.

OK.  Does this mean "pci@" and "pcie@" should only represent bridge
devices?  (These devices are all endpoints and erroneously had
device_type = "pci" properties, among other things, so I'm already
fixing that.)

Do you want me to make a (separate) change to treat "pci" the
same as "pcie"?

> These are ethernet devices, right? Then the right name is
> 'ethernet@0,0'. If not, then pick something that matches what the node
> is. Both pci and pcie mean the node implements a PCI bus.

They implement Ethernet devices, yes.  But they are used for
pci-ep-bus (and the Ethernet devices bind to a sub-node), and
that's what's important about these nodes.  What's the right
name?  The dynamically-generated node uses "dev@".

Is "ethernet@" still right, if it's also used to access a
clock and a reset and ... via pci-ep-bus?

I want to use the right name, I'm just unsure about what that
is, given its use for access via pci-ep-bus.

Thanks.

					-Alex



> Rob