Re: [PATCH] PCI: xgene: Fix IB window setup

Thorsten Leemhuis
2022-02-21T11:52:11Z

Hi, this is your Linux kernel regression tracker speaking. Top-posting
for once, to make this easy accessible to everyone.

What's the status of this regression and getting it fixed? It looks like
there was quite some progress for a while, but then things seem to have
come to a halt ten days ago. Could anyone please provide a status
update, please?

Ciao, Thorsten (wearing his 'Linux kernel regression tracker' hat)

P.S.: As a Linux kernel regression tracker I'm getting a lot of reports
on my table. I can only look briefly into most of them. Unfortunately
therefore I sometimes will get things wrong or miss something important.
I hope that's not the case here; if you think it is, don't hesitate to
tell me about it in a public reply, that's in everyone's interest.

#regzbot poke

On 11.02.22 03:16, dann frazier wrote:
> On Tue, Feb 08, 2022 at 08:34:45AM -0600, Rob Herring wrote:
>> On Mon, Feb 7, 2022 at 7:19 PM dann frazier <dann.frazier@canonical.com> wrote:
>>>
>>> On Mon, Feb 07, 2022 at 10:09:31AM -0600, Rob Herring wrote:
>>>> On Sat, Feb 5, 2022 at 3:13 PM dann frazier <dann.frazier@canonical.com> wrote:
>>>>>
>>>>> On Sat, Feb 5, 2022 at 9:05 AM Rob Herring <robh@kernel.org> wrote:
>>>>>>
>>>>>> On Fri, Feb 4, 2022 at 5:01 PM dann frazier <dann.frazier@canonical.com> wrote:
>>>>>>>
>>>>>>> On Mon, Nov 29, 2021 at 11:36:37AM -0600, Rob Herring wrote:
>>>>>>>> Commit 6dce5aa59e0b ("PCI: xgene: Use inbound resources for setup")
>>>>>>>> broke PCI support on XGene. The cause is the IB resources are now sorted
>>>>>>>> in address order instead of being in DT dma-ranges order. The result is
>>>>>>>> which inbound registers are used for each region are swapped. I don't
>>>>>>>> know the details about this h/w, but it appears that IB region 0
>>>>>>>> registers can't handle a size greater than 4GB. In any case, limiting
>>>>>>>> the size for region 0 is enough to get back to the original assignment
>>>>>>>> of dma-ranges to regions.
>>>>>>>
>>>>>>> hey Rob!
>>>>>>>
>>>>>>> I've been seeing a panic on HP Moonshoot m400 cartridges (X-Gene1) -
>>>>>>> only during network installs - that I also bisected down to commit
>>>>>>> 6dce5aa59e0b ("PCI: xgene: Use inbound resources for setup"). I was
>>>>>>> hoping that this patch that fixed the issue on Stéphane's X-Gene2
>>>>>>> system would also fix my issue, but no luck. In fact, it seems to just
>>>>>>> makes it fail differently. Reverting both patches is required to get a
>>>>>>> v5.17-rc kernel to boot.
>>>>>>>
>>>>>>> I've collected the following logs - let me know if anything else would
>>>>>>> be useful.
>>>>>>>
>>>>>>> 1) v5.17-rc2+ (unmodified):
>>>>>>> http://dannf.org/bugs/m400-no-reverts.log
>>>>>>> Note that the mlx4 driver fails initialization.
>>>>>>>
>>>>>>> 2) v5.17-rc2+, w/o the commit that fixed Stéphane's system:
>>>>>>> http://dannf.org/bugs/m400-xgene2-fix-reverted.log
>>>>>>> Note the mlx4 MSI-X timeout, and later panic.
>>>>>>>
>>>>>>> 3) v5.17-rc2+, w/ both commits reverted (works)
>>>>>>> http://dannf.org/bugs/m400-both-reverted.log
>>>>>>
>>>>>> The ranges and dma-ranges addresses don't appear to match up with any
>>>>>> upstream dts files. Can you send me the DT?
>>>>>
>>>>> Sure: http://dannf.org/bugs/fdt
>>>>
>>>> The first fix certainly is a problem. It's going to need something
>>>> besides size to key off of (originally it was dependent on order of
>>>> dma-ranges entries).
>>>>
>>>> The 2nd issue is the 'dma-ranges' has a second entry that is now ignored:
>>>>
>>>> dma-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00>, <0x00
>>>> 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>>>
>>>> Based on the flags (3rd addr cell: 0x0), we have an inbound config
>>>> space which the kernel now ignores because inbound config space
>>>> accesses make no sense. But clearly some setup is needed. Upstream, in
>>>> contrast, sets up a memory range that includes this region, so the
>>>> setup does happen:
>>>>
>>>> <0x42000000 0x00 0x00000000 0x00 0x00000000 0x80 0x00000000>
>>>>
>>>> Minimally, I suspect it will work if you change dma-ranges 2nd entry to:
>>>>
>>>> <0x42000000 0x79000000 0x00 0x79000000 0x00 0x800000>
>>>
>>> Thanks for looking into this Rob. I tried to test that theory, but it
>>> didn't seem to work. This is what I tried:
>>>
>>> --- m400.dts 2022-02-07 20:16:44.840475323 +0000
>>> +++ m400.dts.dmaonly 2022-02-08 00:17:54.097132000 +0000
>>> @@ -446,7 +446,7 @@
>>> reg = <0x00 0x1f2b0000 0x00 0x10000 0xe0 0xd0000000 0x00 0x200000 0x00 0x79e00000 0x00 0x2000000 0x00 0x79000000 0x00 0x800000>;
>>> reg-names = "csr\0cfg\0msi_gen\0msi_term";
>>> ranges = <0x1000000 0x00 0x00 0xe0 0x10000000 0x00 0x10000 0x2000000 0x00 0x30000000 0xe1 0x30000000 0x00 0x80000000>;
>>> - dma-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x00 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> + dma-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x42000000 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> ib-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x00 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> ib-ranges-ep = <0x2000000 0x00 0x00 0x00 0x00 0x00 0x400000 0x2000000 0x00 0x00 0x00 0x00 0x00 0x400000 0x2000000 0x00 0x79000000 0x00 0x79000000 0x00 0x100000>;
>>> interrupts = <0x00 0x10 0x04>;
>>> @@ -471,7 +471,7 @@
>>> reg = <0x00 0x1f2c0000 0x00 0x10000 0xd0 0xd0000000 0x00 0x200000 0x00 0x79e00000 0x00 0x2000000 0x00 0x79000000 0x00 0x800000>;
>>> reg-names = "csr\0cfg\0msi_gen\0msi_term";
>>> ranges = <0x1000000 0x00 0x00 0xd0 0x10000000 0x00 0x10000 0x2000000 0x00 0x30000000 0xd1 0x30000000 0x00 0x80000000>;
>>> - dma-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x00 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> + dma-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x42000000 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> ib-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x00 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> ib-ranges-ep = <0x2000000 0x00 0x00 0x00 0x00 0x00 0x400000 0x2000000 0x00 0x00 0x00 0x00 0x00 0x400000 0x2000000 0x00 0x79000000 0x00 0x79000000 0x00 0x100000>;
>>> interrupts = <0x00 0x10 0x04>;
>>> @@ -496,7 +496,7 @@
>>> reg = <0x00 0x1f2d0000 0x00 0x10000 0x90 0xd0000000 0x00 0x200000 0x00 0x79e00000 0x00 0x2000000 0x00 0x79000000 0x00 0x800000>;
>>> reg-names = "csr\0cfg\0msi_gen\0msi_term";
>>> ranges = <0x1000000 0x00 0x00 0x90 0x10000000 0x00 0x10000 0x2000000 0x00 0x30000000 0x91 0x30000000 0x00 0x80000000>;
>>> - dma-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x00 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> + dma-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x42000000 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> ib-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x00 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> ib-ranges-ep = <0x2000000 0x00 0x00 0x00 0x00 0x00 0x400000 0x2000000 0x00 0x00 0x00 0x00 0x00 0x400000 0x2000000 0x00 0x79000000 0x00 0x79000000 0x00 0x100000>;
>>> interrupts = <0x00 0x10 0x04>;
>>> @@ -522,7 +522,7 @@
>>> reg = <0x00 0x1f500000 0x00 0x10000 0xa0 0xd0000000 0x00 0x200000 0x00 0x79e00000 0x00 0x2000000 0x00 0x79000000 0x00 0x800000>;
>>> reg-names = "csr\0cfg\0msi_gen\0msi_term";
>>> ranges = <0x2000000 0x00 0x30000000 0xa1 0x30000000 0x00 0x80000000>;
>>> - dma-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x00 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> + dma-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x42000000 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> ib-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x00 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> ib-ranges-ep = <0x2000000 0x00 0x00 0x00 0x00 0x00 0x400000 0x2000000 0x00 0x00 0x00 0x00 0x00 0x400000 0x2000000 0x00 0x79000000 0x00 0x79000000 0x00 0x100000>;
>>> interrupts = <0x00 0x10 0x04>;
>>> @@ -547,7 +547,7 @@
>>> reg = <0x00 0x1f510000 0x00 0x10000 0xc0 0xd0000000 0x00 0x200000 0x00 0x79e00000 0x00 0x2000000 0x00 0x79000000 0x00 0x800000>;
>>> reg-names = "csr\0cfg\0msi_gen\0msi_term";
>>> ranges = <0x1000000 0x00 0x00 0xc0 0x10000000 0x00 0x10000 0x2000000 0x00 0x30000000 0xc1 0x30000000 0x00 0x80000000>;
>>> - dma-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x00 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> + dma-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x42000000 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> ib-ranges = <0x42000000 0x40 0x00 0x40 0x00 0x40 0x00 0x00 0x00 0x79000000 0x00 0x79000000 0x00 0x800000>;
>>> ib-ranges-ep = <0x2000000 0x00 0x00 0x00 0x00 0x00 0x400000 0x2000000 0x00 0x00 0x00 0x00 0x00 0x400000 0x2000000 0x00 0x79000000 0x00 0x79000000 0x00 0x100000>;
>>> interrupts = <0x00 0x10 0x04>;
>>>
>>> And that failed to boot with a 5.17-rc3. Since dma-ranges was
>>> previously identical to ib-ranges, I also tried making the same change
>>> to ib-ranges, but with no success.
>>
>> Failed to boot at all or just PCIe still didn't work causing boot to
>> eventually fail?
>
> Sorry, I mean PCIe still didn't work, here's the log:
> http://dannf.org/bugs/m400-tweaked_dtb.log
> (unmodified kernel source w/ above dtb change)
>
>> 'ib-ranges' is unknown to the kernel, so the firmware
>> is using it somehow?
>>
>> You also need to revert the first fix for PCIe to work.
>
> Oh, OK. I misunderstood. I tried reverting commit 6dce5aa59e0b "PCI:
> xgene: Use inbound resources for setup" along with a dtb with the
> dma-ranges change in the diff above, but PCIe still didn't
> work. Here's the log:
>
> http://dannf.org/bugs/m400-6dce5aa5_reverted+tweaked_dtb.log
>
> -dann
>
>>
>>>> While we shouldn't break existing DTs, the moonshot DT doesn't use
>>>> what's documented upstream. There are multiple differences compared to
>>>> what's documented. Is upstream supposed to support upstream DTs,
>>>> downstream DTs, and ACPI for XGene which is an abandoned platform with
>>>> only a handful of users?
>>>
>>> That's a fair question, though it's one of a policy, and I feel I'd be
>>> overstepping by weighing in. I suppose one option I have is to try
>>> and create and upstream a dts for these systems and modify our
>>> boot.scr to always load that over the one provided by firmware. While
>>> we do have some of these systems in production, they are being retired
>>> and replaced with newer kit over time, and it's possible we'll never
>>> need to upgrade them to a modern kernel.
>>>
>>> -dann