[RFC RFT PATCH v1 0/1] ARM: orion5x: convert D-Link DNS-323 to the Device Tree

[Mauri Sandberg]

On 28.4.2022 23.56, Arnd Bergmann wrote:
> On Thu, Apr 28, 2022 at 10:01 PM Mauri Sandberg <maukka at ext.kapsi.fi> wrote:
>> On 27.4.2022 21.10, Arnd Bergmann wrote:
>>> On Wed, Apr 27, 2022 at 6:21 PM Mauri Sandberg <maukka at ext.kapsi.fi> wrote:
>>>> - sata_mv fails to initialise with -22 (-EINVAL)
>>>
>>> No idea, I'd try inserting a printk in every code path that can return -EINVAL
>>> from there
>>>

With debugging the reason for -EINVAL remains a bit mystery.
  - sata_mv calls ata_host_activate() [1]
  - later on, in request_threaded_irq(), there are sanity checks [2]
  - that fail with irq_settings_can_request() returning 0 [3]

I cannot really put my finger on why the irq cannot be requested in DT
approach.

>> Is there a way to describe the PCIe bus in the
>> device tree? The initalisation of that bus is done for rev A1 only.
> 
> I'm not too familiar with the platform, but my interpretation is that the
> DT support here is incomplete:
> 
> The DT based PCI probe using drivers/pci/controller/pci-mvebu.c
> is not hooked up in orion5x.dtsi, and the traditional pci code does
> not work with DT.

Can the existing pci code still be used to init the PCI bus and describe
the rest in the DT or is it a futile attempt?

> I see that orion5x has two separate blocks --  a PCIe host that is
> similar to the kirkwood one, and a legacy PCI host that needs
> a completely separate driver.
> 
> Which of the two do you actually need here?
> 

I really cannot say which one is it. How can I tell? The functions given
in struct hw_pci find their way to drivers/pci/probe.c eventually and
use pci_scan_root_bus_bridge(). Nothing seems to utilising mvebu or
kirkwood explicitly at least.

Here's the output from lspci if the ids reveal anything.

# lspci -v -k
00:00.0 Class 0580: 11ab:5181
01:00.0 Class 0580: 11ab:5181
00:01.0 Class 0100: 11ab:7042 sata_mv

-- Mauri

[1] 
https://elixir.bootlin.com/linux/v5.17/source/drivers/ata/sata_mv.c#L4434

[2] https://elixir.bootlin.com/linux/v5.17/source/kernel/irq/manage.c#L2146

[3] https://elixir.bootlin.com/linux/v5.17/source/kernel/irq/settings.h#L100