Re: [PATCH] PCI: Do not use pcie_get_speed_cap() to determine when to start waiting

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Tue, May 12, 2020 at 12:09:06PM -0500, Bjorn Helgaas wrote:
> I think that code would be more readable as something like:
> 
>   if (dev->link_active_reporting)
>     wait_for_link_active(dev);
>   msleep(delay);
> 
> Obviously we still want the printks and error/timeout checking, but
> fundamentally we want to wait for the link to be active (if possible),
> then wait the 100ms.  That structure isn't as clear as it could be
> when the delay is buried inside pcie_wait_for_link_delay().
> 
> It's not completely trivial to restructure it like that because of
> pcie_wait_for_link() and its callers.  But I think it's worth pushing
> on it a little bit to see if it could be done reasonably.

OK, I see what I can do to make it clearer.

> This does expose the fact that per spec, a hot-plug capable port that
> supports only 5 GT/s must support link_active_reporting, but sec 6.6.1
> says we *don't* need to wait for link training to complete before
> waiting 100ms.  So maybe we end up waiting slightly more than
> necessary.  Probably not worth worrying about?

I would say so. Better wait a bit too much than the opposite IMHO.