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

[York Sun]

+Xiaowei

On 08/28/2017 10:09 AM, Joakim Tjernlund wrote:
> 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 .. :)
>>   
>> https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fpatchwork.ozlabs.org%2Fpatch%2F801519%2F&data=01%7C01%7Cyork.sun%40nxp.com%7Cf46ff5111ba04e631a9b08d4ee377ecc%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0&sdata=n9%2B2NIjEvsMBCljRLHS6NVVN4ANa3nBGpwUjI4Od%2Bhs%3D&reserved=0.
> 
> 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.
> 

Xiaowei, can you comment?

York