Thread (18 messages) 18 messages, 3 authors, 2021-08-12

Re: [PATCH v3 0/4] DT schema changes for HiKey970 PCIe hardware to work

From: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Date: 2021-08-05 07:46:25
Also in: linux-devicetree, linux-pci, lkml

Em Wed, 4 Aug 2021 10:28:53 -0600
Rob Herring [off-list ref] escreveu:
On Wed, Aug 04, 2021 at 08:50:45AM +0200, Mauro Carvalho Chehab wrote:
quoted
Em Tue, 3 Aug 2021 16:11:42 -0600
Rob Herring [off-list ref] escreveu:
  
quoted
On Mon, Aug 2, 2021 at 10:39 PM Mauro Carvalho Chehab
[off-list ref] wrote:  
quoted
Hi Rob,

That's the third version of the DT bindings for Kirin 970 PCIE and its
corresponding PHY.

It is identical to v2, except by:
        -          pcie@7,0 { // Lane 7: Ethernet
        +          pcie@7,0 { // Lane 6: Ethernet    
Can you check whether you have DT node links in sysfs for the PCI
devices? If you don't, then something is wrong still in the topology
or the PCI core is failing to set the DT node pointer in struct
device. Though you don't rely on that currently, we want the topology
to match. It's possible this never worked on arm/arm64 as mainly
powerpc relied on this.

I'd like some way to validate the DT matches the PCI topology. We
could have a tool that generates the DT structure based on the PCI
topology.  
The of_node node link is on those places:

	$ find /sys/devices/platform/soc/f4000000.pcie/ -name of_node
	/sys/devices/platform/soc/f4000000.pcie/of_node
	/sys/devices/platform/soc/f4000000.pcie/pci0000:00/0000:00:00.0/of_node
	/sys/devices/platform/soc/f4000000.pcie/pci0000:00/0000:00:00.0/pci_bus/0000:01/of_node
	/sys/devices/platform/soc/f4000000.pcie/pci0000:00/pci_bus/0000:00/of_node  
Looks like we're missing some... 

It's not immediately obvious to me what's wrong here. Only the root 
bus is getting it's DT node set. The relevant code is pci_scan_device(), 
pci_set_of_node() and pci_set_bus_of_node(). Give me a few days to try 
to reproduce and debug it.
I added a printk on both pci_set_*of_node() functions:

	[    4.872991]  (null): pci_set_bus_of_node: of_node: /soc/pcie@f4000000
	[    4.913806]  (null): pci_set_of_node: of_node: /soc/pcie@f4000000
	[    4.978102] pci_bus 0000:01: pci_set_bus_of_node: of_node: /soc/pcie@f4000000/pcie@0,0
	[    4.990622]  (null): pci_set_of_node: of_node: /soc/pcie@f4000000/pcie@0,0
	[    5.052383] pci_bus 0000:02: pci_set_bus_of_node: of_node: (null)
	[    5.059263]  (null): pci_set_of_node: of_node: (null)
	[    5.085552]  (null): pci_set_of_node: of_node: (null)
	[    5.112073]  (null): pci_set_of_node: of_node: (null)
	[    5.138320]  (null): pci_set_of_node: of_node: (null)
	[    5.164673]  (null): pci_set_of_node: of_node: (null)
	[    5.233759] pci_bus 0000:03: pci_set_bus_of_node: of_node: (null)
	[    5.240539]  (null): pci_set_of_node: of_node: (null)
	[    5.310545] pci_bus 0000:04: pci_set_bus_of_node: of_node: (null)
	[    5.324719] pci_bus 0000:05: pci_set_bus_of_node: of_node: (null)
	[    5.338914] pci_bus 0000:06: pci_set_bus_of_node: of_node: (null)
	[    5.345516]  (null): pci_set_of_node: of_node: (null)
	[    5.415795] pci_bus 0000:07: pci_set_bus_of_node: of_node: (null)

It sounds that the parent is missing when pci_set_bus_of_node() is
called on some places. I'll try to identify why.

Thanks,
Mauro

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