[PATCH 1/4] PCI: dw-rockchip: Do not enumerate bus before endpoint devices are ready

[Manivannan Sadhasivam]

On Thu, Jun 12, 2025 at 07:21:08AM -0500, Bjorn Helgaas wrote:
> On Thu, Jun 12, 2025 at 01:40:23PM +0200, Niklas Cassel wrote:
> > On Thu, Jun 12, 2025 at 06:38:27AM -0500, Bjorn Helgaas wrote:
> > > On Thu, Jun 12, 2025 at 01:19:45PM +0200, Niklas Cassel wrote:
> > > > On Wed, Jun 11, 2025 at 04:14:56PM -0500, Bjorn Helgaas wrote:
> > > > > On Wed, Jun 11, 2025 at 12:51:42PM +0200, Niklas Cassel wrote:
> > > > > > Commit ec9fd499b9c6 ("PCI: dw-rockchip: Don't wait for link since we can
> > > > > > detect Link Up") changed so that we no longer call dw_pcie_wait_for_link(),
> > > > > > and instead enumerate the bus directly after receiving the Link Up IRQ.
> > > > > > 
> > > > > > This means that there is no longer any delay between link up and the bus
> > > > > > getting enumerated.
> > > 
> > > > > I think the comment at the PCIE_T_RRS_READY_MS definition should be
> > > > > enough (although it might need to be updated to mention link-up).
> > > > > This delay is going to be a standard piece of every driver, so it
> > > > > won't require special notice.
> > > > 
> > > > Looking at pci.h, we already have a comment mentioning exactly this
> > > > (link-up):
> > > > https://github.com/torvalds/linux/blob/v6.16-rc1/drivers/pci/pci.h#L51-L63
> > > > 
> > > > I will change the patches to use PCIE_RESET_CONFIG_DEVICE_WAIT_MS instead.
> > > 
> > > I'll more closely later, but I think PCIE_T_RRS_READY_MS and
> > > PCIE_RESET_CONFIG_DEVICE_WAIT_MS are duplicates and only one should
> > > exist.  It looks like they got merged at about the same time by
> > > different people, so we didn't notice.
> > 
> > I came to the same conclusion, I will send a patch to remove
> > PCIE_T_RRS_READY_MS and convert the only existing user to use
> > PCIE_RESET_CONFIG_DEVICE_WAIT_MS.
> 
> I think PCIE_T_RRS_READY_MS expresses the purpose of the wait more
> specifically.  It's not that the device is completely ready after
> 100ms; just that it should be able to respond with RRS if it needs
> more time.

Yes, but none of the drivers are checking for the RRS status currently. So using
PCIE_T_RRS_READY_MS gives a wrong impression that the driver is waiting for the
RRS status from the device.

- Mani

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