linux-kernel - Re: Linux Kernel Regression: HAPS quirk breaks PCIe on i.MX6QP

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Message-ID: <30102591E157244384E984126FC3CB4F639BECAB@us01wembx1.internal.synopsys.com>
Date:   Thu, 31 Jan 2019 23:46:23 +0000
From:   Thinh Nguyen <thinh.nguyen@...opsys.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>,
        "Lukas F. Hartmann" <lukas@...mn.com>
CC:     "thinh.nguyen@...opsys.com" <thinh.nguyen@...opsys.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        Lucas Stach <l.stach@...gutronix.de>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        John Youn <john.youn@...opsys.com>
Subject: Re: 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 <lukas@...mn.com> wrote:
>>> Hi Thinh,
>>>
>>> I'm writing you because you're the author in this commit:
>>> https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_torvalds_linux_commit_03e6742584af8866ba014874669d0440bed3a623&d=DwIBaQ&c=DPL6_X_6JkXFx7AXWqB0tg&r=VKipRJmm95P2RbIxyKKYrcUCOGNlQtjlV-5zhrVhIik&m=2sOrowYXlsC3rl0LfHQhIZzImag0jFZXGvR6NIQDsh8&s=oJoBWRE8_LGAYbX2alh6QnjYZTTmzcgLw4MtOMToNyo&e=
>>>
>>> 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:
>>>
>>> https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_torvalds_linux_blob_master_include_linux_pci-5Fids.h-23L2364&d=DwIBaQ&c=DPL6_X_6JkXFx7AXWqB0tg&r=VKipRJmm95P2RbIxyKKYrcUCOGNlQtjlV-5zhrVhIik&m=2sOrowYXlsC3rl0LfHQhIZzImag0jFZXGvR6NIQDsh8&s=-FVCwe81XNjJsYHYk1w-kdAzSOLunTGeNc73azO2QYw&e=
>>>
>>> Here is a bit of lspci output on my i.MX6QP machine (without the problem):
>>>
>>> mntmn@...orm:~/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;
 
+       if (class != PCI_CLASS_SERIAL_USB_XHCI)
+               return;
+
        switch (pdev->device) {
        case PCI_DEVICE_ID_SYNOPSYS_HAPSUSB3:
        case PCI_DEVICE_ID_SYNOPSYS_HAPSUSB3_AXI:

Thanks,
Thinh