CONFIG_PCIEASPM breaks PCIe on Marvell Armada 385 machine
Russell King - ARM Linux
linux at armlinux.org.uk
Wed Jan 18 09:55:20 PST 2017
On Wed, Jan 18, 2017 at 09:36:55AM -0800, David Daney wrote:
> On 01/18/2017 06:22 AM, Bjorn Helgaas wrote:
> The tricky thing here is assigning the blame for failure in link training.
> In the case in question we spent many months analysing the analog properties
> of the bus and examining/decoding analog scope captures of the failures
> before credibly assigning blame to the other guy. Usually what happens is
> the device vendor accurately claims that their device works flawlessly in
> conjunction with certain Intel root ports, so the problem must be fixed in
> the root port of the failing system. If you have a black list, you may be
> disabling ASPM in systems where it can work without failures.
So what we need is not a table of just devices, but a combination of
devices... iow, "when root A and endpoint B are combined, retrains
need to be avoided."
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