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SubjectRe: Linux Kernel Regression: HAPS quirk breaks PCIe on i.MX6QP
Hi Lukas,

Thinh Nguyen wrote:
> Bjorn Helgaas wrote:
>> [+cc linux-pci, linux-kernel]
>> On Thu, Jan 31, 2019 at 11:21 AM Lukas F. Hartmann <> wrote:
>>> Hi Thinh,
>>> I'm writing you because you're the author in this commit:
>>> This quirk workaround breaks the PCIe on i.MX6QP, at least on my test
>>> devices. The reason is because the Synposys PCIe IP in i.MX6QP has the
>>> same device ID as the HAPS USB3 controller you are targeting in the
>>> commit: 0xabcd.
>>> Definition:
>>> Here is a bit of lspci output on my i.MX6QP machine (without the problem):
>>> mntmn@reform:~/code/linux$ lspci -v
>>> 00:00.0 PCI bridge: Synopsys, Inc. Device abcd (rev 01) (prog-if 00
>>> ^^^^
>>> [Normal decode])
>>> Flags: bus master, fast devsel, latency 0, IRQ 307
>>> Memory at 01000000 (32-bit, non-prefetchable) [size=1M]
>>> Bus: primary=00, secondary=01, subordinate=ff, sec-latency=0
>>> ...
>>> The failure mode is that the PCIe controller shows up as a USB
>>> controller and my ath9k wireless PCIe card cannot be assigned the
>>> proper resources anymore (-ENOMEM even for very small BARs).
>>> Reverting this commit fixes the problem for me. I suggest to make the
>>> check more specific to the platform/chipset you are targeting.
>> So Synopsys apparently re-used Device ID 0xabcd? That's a pretty bad problem.
>> It looks like we merged 03e6742584af ("PCI: Override Synopsys USB 3.x
>> HAPS device class") for v5.0, and v5.0-final hasn't been released yet,
>> so if we don't hear from Thinh with a resolution, we can still revert
>> it.
>> I set myself a reminder to revert this on Feb 11, but hopefully we'll
>> have a better resolution before then.
>> Bjorn
> This is really odd that the PID for the PCIe controller in i.MX6QP is
> the same as PID Synopsys use for USB controller. We use a different set
> of PIDs for PCIe controllers and track VID and PID in our releases.
> Is the Root Complex (00:00.0) part of the SoC? Or is this a Synopsys
> prototype connected to your board? If it is the latter, then the FPGA
> configuration needs to be updated to other PID.
> We're investigating the workaround in case this is on a taped-out SoC.

Can you try to see if this will help?

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index b0a413f3f7ca..64623fbdd1e5 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -629,6 +629,9 @@ static void quirk_synopsys_haps(struct pci_dev *pdev)
u32 class = pdev->class;

+ return;
switch (pdev->device) {

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