Re: [V3] PCI: fu740: Drop to 2.5GT/s to fix initial device probing on some boards

[Ben Dooks]

On 14/04/2022 01:10, Maciej W. Rozycki wrote:
> On Wed, 23 Mar 2022, Ben Dooks wrote:
>
> > > FWIW, I have tested this and it solved my issue with nvme not being probed,
> > > so:
> > >
> > > Tested-by: Alexandre Ghiti <alexandre.ghiti@xxxxxxxxxxxxx>
> >
> > Ok, great. Our test rig seems to be still working with this.
>
>   I ran simple verification of your change by interrupting U-Boot after a
> power-up and issuing:
>
> => setenv boot_pci_enum true
>
> at the command prompt before booting from the uSD card and curiously
> enough the root port comes up with the Link Capabilities Register
> reporting the lack of Link Bandwidth Notification Capability in this
> scenario, while it reports its presence if booted undisturbed, i.e.:
>
> 		LnkCap: Port #0, Speed 8GT/s, Width x8, ASPM L0s L1, Exit Latency L0s <4us, L1 <4us
> 			ClockPM- Surprise- LLActRep+ BwNot- ASPMOptComp+
>
> vs:
>
> 		LnkCap: Port #0, Speed 8GT/s, Width x8, ASPM L0s L1, Exit Latency L0s <4us, L1 <4us
> 			ClockPM- Surprise- LLActRep+ BwNot+ ASPMOptComp+
>
> It is fully reproducible.
>
>   Any idea what might be causing it?  I can't see it being explicitly set
> or cleared anywhere, be it in U-Boot or Linux, so it must be done by the
> device itself depending on something.  And the lack of this capability
> seems to me like non-compliance for a multiple-lane, multiple-speed
> device.

I'll see if we can reproduce this


--
Ben Dooks				http://www.codethink.co.uk/
Senior Engineer				Codethink - Providing Genius

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