Re: [PATCH 1/3] PCI: dwc: ep: Add dw_pcie_ep_deinit_notify()

Manivannan Sadhasivam
2024-05-29T15:40:12Z

On Wed, May 29, 2024 at 04:54:57PM +0200, Niklas Cassel wrote:
> On Wed, May 29, 2024 at 07:46:14PM +0530, Manivannan Sadhasivam wrote:
> >
> > That's fine. Thanks a lot for stepping in to fix the build issue. I was on
> > vacation, so couldn't act on your query/series promptly.
>
> Welcome back ;)
>
>
> >
> > Let us conclude the fix here itself as we have more than 1 threads going on.
> > I did consider adding the stubs to pci-epc.h, but only the deinit API requires
> > that. So I thought it will look odd to add stub for only one function, that too
> > for one of the two variants (init/deinit).
> >
> > So I went ahead with the ugly (yes) conditional for the deinit_notify API.
> >
> > Ideally, I would've expected both dwc and EP subsystem to provide stubs for the
> > APIs used by the common driver (host and EP). But since the controller drivers
> > were using the conditional check to differentiate between host and EP mode,
> > compilers were smart enough to spot the dead functions and removes them. So
> > there were no reports so far.
> >
> > But in this case, the pci_epc_deinit_notify() is called in a separate helper and
> > hence the issue.
> >
> > So to conclude, I think it is best if we can add stub just for
> > pci_epc_deinit_notify() in pci-epc.h and get rid of the dummy
> > dw_pcie_ep_init_notify() wrapper to make the init/deinit API usage consistent.
> >
> > Also I do not want to remove the wrapper for dw_pcie_ep_linkup() since its
> > conterpart dw_pcie_ep_linkdown() is required.
>
> I see, sounds good.
>
> However, if we add a stub for pci_epc_deinit_notify(), it makes sense to also
> add a stub for pci_epc_init_notify(). (I'm quite sure tegra will fail to link
> if you change it from dw_pcie_ep_init_notify() to pci_epc_init_notify()
> otherwise.)
>

No it doesn't. Reason is, the EP IRQ handler itself gets optimized out due to
the CONFIG_PCIE_TEGRA194_EP check in tegra_pcie_dw_probe().

> We should probably also address Bjorn comment:
> "ls and qcom even use *both*: pci_epc_linkdown() but dw_pcie_ep_linkup()."
>
> As far as I can tell, it is only ls (not sure why Bjorn also mentioned qcom):
> drivers/pci/controller/dwc/pci-layerscape-ep.c: pci_epc_linkdown(pci->ep.epc);
> But this should probably also be fixed to use dw_pcie_ep_linkdown().
>

Agree. I will fix that also.

- Mani

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