[U-Boot] FSL PCIe LTSSM >= PCI_LTSSM_L0 equals link up

[Joakim Tjernlund]

On Mon, 2017-08-28 at 16:55 +0000, York Sun wrote:
> On 08/28/2017 09:48 AM, Joakim Tjernlund wrote:
> > FSL PCIe controller drivers before REV 3 has this test for link up:
> >    enabled = ltssm >= PCI_LTSSM_L0;
> > 
> > We have a PCIe dev. that stays in LTSSM=0x51 (Polling Compliance) when non ready
> > for PCI transaktions. When FSL PCIe controller tries to access this device, it
> > hangs forever.
> > 
> > Is LTSSM=0x51 really a "legal" state for link up?
> > If not, what is a suitable range(maybe LO <= ltssm <= L0s(0x27)) ?
> > 
> >   Jocke
> > 
> > BTW, the same test is valid in Linux too.
> > 
> 
> Jocke,
> 
> I am not an expert on PCIe. Please if this thread is helpful,
Me neither .. :)
>  
> http://patchwork.ozlabs.org/patch/801519/.

It mentions polling compliance but this driver already tests for:
if (ltssm < LTSSM_PCIE_L0)
		return 0; 
	return 1;

It just adds some delay if the device is in Polling Compliance to see if that
changes to L0.
Since both layerscape and fsl >= rev 3 already require ltssm to be == L0, I suspect
the ltssm >= L0 is bogus.

 Jocke