Re: [PATCH] Copy bus scanning workaround from ARM Juno PCIe driver.

[Scott Telford <stelford@cadence.com>]

> From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
> Sent: 26 May 2017 18:38
> To: Leif Lindholm <leif.lindholm@linaro.org>
> Cc: Scott Telford <stelford@cadence.com>; edk2-devel@lists.01.org <edk2-
> devel@ml01.01.org>; Tian, Feng <feng.tian@intel.com>; Zeng, Star
> <star.zeng@intel.com>
> Subject: Re: [edk2] [PATCH] Copy bus scanning workaround from ARM Juno
> PCIe driver.

> I'd still like to understand why this issue does not occur under
> Linux, or if it does occur, if we need an ECAM quirk for Juno to work
> around it.
> 
> Could you give an example of which hardware combination triggers this
> issue?

I don't have access to a Juno board here, so can't reproduce the original problem. It would certainly be interesting to know if the current Juno platform code using the generic PCIe driver suffers from the same problem or not.

The platform I've been working with only exists within a Cadence emulation environment. I've seen the problem when testing an ASMedia ASM1182e bridge and an Intel I210 Ethernet card so it's probably not specific to certain PCIe bridges/devices.

The original Juno PCIe driver (including the workaround) was committed by Olivier Martin at ARM, but I'm not sure if he's still there?

I'm working on moving the workaround into the PciExpressLib layer.

Regards,
Scott.