[PATCH v5 2/4] PCI: Use standard wait times for PCIe link monitoring

[Manivannan Sadhasivam]

On Thu, May 28, 2026 at 08:44:07AM +0200, Thierry Reding wrote:
> On Wed, May 27, 2026 at 07:22:55PM +0200, Lukas Wunner wrote:
> > On Wed, May 27, 2026 at 10:28:51AM +0200, Thierry Reding wrote:
> > > On Tue, May 26, 2026 at 01:10:39PM +0200, Lukas Wunner wrote:
> > > > On Tue, May 26, 2026 at 10:53:11AM +0200, Thierry Reding wrote:
> > > > > Instead of defining the wait values for each driver, use common values
> > > > > defined in the core pci.h header file. Note that most drivers don't use
> > > > > the millisecond waits, but rather usleep_range(), so add these commonly
> > > > > used values to the header so that all drivers can use them.
> > > > 
> > > > Hm, why not just replace usleep_range() with msleep() and use the existing
> > > > macro instead of defining new ones?
> > > 
> > > I'm trying to somewhat unify the implementations across drivers without
> > > changing behaviour. I don't have a way of testing any of these drivers,
> > > so keeping the existing implementation and just switching out the symbol
> > > seemed like a good compromise.
> > 
> > It looks like the code was copy-pasted from one driver to the next
> > and I applaud every effort to deduplicate, unify and simplify things.
> > 
> > I don't quite see how using msleep() instead of usleep_range()
> > should result in breakage.  The drivers are just polling for
> > link up for an amount of time and as long as you're not decreasing
> > that amount, everything ought to be fine.  Moving to msleep()
> > should never decrease the amount.
> > 
> > > Then again, I count 2 drivers (in linux-next) that use the existing
> > > PCIE_LINK_WAIT_SLEEP_MS, one of which multiplies by MILLI to get at the
> > > US version (so it could easily be converted to the US_MIN version). Only
> > > pcie-designware.c uses msleep() with PCIE_LINK_WAIT_SLEEP_MS, so it is
> > > clearly the outlier.
> > 
> > Konrad Dybcio went ahead and replaced usleep_range() with msleep()
> > in that driver, kudos to him.  Cf. b262518262f5 ("PCI: dwc: Use msleep()
> > in dw_pcie_wait_for_link()").  If you could just carry over that change
> > to the other drivers that would be great.
> 
> Alright, I see you really don't like usleep_range(), so msleep() it'll
> be.
> 

The rationale behind commit b262518262f5 was to comply with the documentation
that recommends using msleep() for delay larger than 10ms:
https://www.kernel.org/doc/html/next/timers/timers-howto.html

So I would also recommend going with msleep().

- Mani

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