RE: [PATCH 0/1] ppc4xx: Fix PCIe scanning for the 460SX

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Thu, 2011-05-12 at 11:16 -0700, Tirumala Marri wrote:
> So what is the best way to handle this?  It appears (based
> on the comments of others and my own experience) that there
> is no DCR that exists and behaves the way that previous SOCs
> behaved to give us the link status? 

 The register above
> PECFGn_DLLSTA is actually in the PCIe configuration space so
> we would have to map that in to be able to read that
> register during the link check.  Is that correct or ok?
> [marri] yes, you need to program DCR register access these local PCIE_CFG
> registers.

We do I think, tho we might have to re-order some stuff. I'm facing a
similar issue with some internal design here, I'm thinking off adding a
new hook to the ppc4xx_pciex_hwops for link checking to replace the SDR
business.

The interesting question of course is whether that 460SX stuff is the
same as what we're using internally :-)

> I've communicated with some people over email and they had
> tried the (PESDRn_HSSLySTS) register.  Recognizing that
> there exists one of these for each port/lane, is there a way
> to use this one?  It is in the indirect DCR space.  I'd
> tried this myself and never did get it to do anything but I
> could have been looking at the wrong lane or something.
> [marri]This is at SERDES level. If this link up doesn't necessarily
> Overall stack is up. This is mostly used for BIST and diagnostics.
> 
> Lastly, what was the reason for forcing the original code to
> be GEN-1 speeds?
> [marri] Gen-2 need some extra checks compared to Gen-1.
> There were not many Gen-2 devices at the time of submission
> To test them.

Can we fix that ?

Cheers,
Ben.