Re: [PATCH] PCI/portdrv: Disable bwctrl service if port is fixed at 2.5 GT/s

Niklas Schnelle
2024-12-12T09:17:52Z

On Thu, 2024-12-12 at 10:08 +0100, Lukas Wunner wrote:
> On Wed, Dec 11, 2024 at 03:07:38PM +0200, Ilpo Järvinen wrote:
> > I recall taking note of this inconsistency in some lspci dumps I've from
> > Mika (but forgot it until now). So I'm afraid it might be more widespread
> > than just TR.
>
> Oh you did? Interesting. After re-reading the spec I'm convinced now
> that we're doing this wrong and that we should honor the Max Link Speed
> instead of blindly deeming all set bits in the Link Capabilities 2
> Register as supported speeds:
>
> https://lore.kernel.org/r/e3386d62a766be6d0ef7138a001dabfe563cdff8.1733991971.git.lukas@wunner.de/
>
> @Niklas, could you test if this is sufficient to avoid the issue?
> Or do we still need to stop instantiating the bandwidth controller
> if more than one speed is supported?
>
> Thanks!
>
> Lukas

Yes, I will test this but will only get to do so tonight (UTC +2). If
it's not sufficient I think we could use the modified
pcie_get_supported_speeds() to check if only one link speed is
supported, right?

Thanks,
Niklas