Re: [PATCH v5] PCI: dwc: Wait for link up only if link is started

[Bjorn Helgaas <helgaas@kernel.org>]

On Fri, Jan 19, 2024 at 01:22:19PM +0530, Manivannan Sadhasivam wrote:
> On Fri, Jan 12, 2024 at 03:00:06PM +0530, Ajay Agarwal wrote:
> > In dw_pcie_host_init() regardless of whether the link has been
> > started or not, the code waits for the link to come up. Even in
> > cases where start_link() is not defined the code ends up spinning
> > in a loop for 1 second. Since in some systems dw_pcie_host_init()
> > gets called during probe, this one second loop for each pcie
> > interface instance ends up extending the boot time.
> 
> Which platform you are working on? Is that upstreamed? You should mention the
> specific platform where you are observing the issue.
> 
> Right now, intel-gw and designware-plat are the only drivers not
> defining that callback. First one definitely needs a fixup and I do
> not know how the latter works.

What fixup do you have in mind for intel-gw?

It looks a little strange to me because it duplicates
dw_pcie_setup_rc() and dw_pcie_wait_for_link(): dw_pcie_host_init()
calls them first via pp->ops->init(), and then calls them a second
time directly:

  struct dw_pcie_host_ops intel_pcie_dw_ops = {
    .init = intel_pcie_rc_init
  }

  intel_pcie_probe
    pp->ops = &intel_pcie_dw_ops
    dw_pcie_host_init(pp)
      if (pp->ops->init)
	pp->ops->init
	  intel_pcie_rc_init
	    intel_pcie_host_setup
	      dw_pcie_setup_rc                        # <--
	      dw_pcie_wait_for_link                   # <--
      dw_pcie_setup_rc                                # <--
      dw_pcie_wait_for_link                           # <--

Is that what you're thinking?

Bjorn