From: Thomas Gleixner <tglx@linutronix.de>
To: Bjorn Helgaas <helgaas@kernel.org>, Kalle Valo <kvalo@codeaurora.org>
Cc: Govind Singh <govinds@codeaurora.org>,
linux-pci@vger.kernel.org, linux-wireless@vger.kernel.org,
Devin Bayer <dev@doubly.so>,
Thomas Krause <thomaskrause@posteo.de>,
ath11k@lists.infradead.org, Christoph Hellwig <hch@lst.de>
Subject: Re: pci_alloc_irq_vectors fails ENOSPC for XPS 13 9310
Date: Tue, 03 Nov 2020 22:08:49 +0100 [thread overview]
Message-ID: <874km61732.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201103160838.GA246433@bjorn-Precision-5520>
On Tue, Nov 03 2020 at 10:08, Bjorn Helgaas wrote:
> On Tue, Nov 03, 2020 at 08:49:06AM +0200, Kalle Valo wrote:
>> Bjorn Helgaas <helgaas@kernel.org> writes:
>> > On Mon, Nov 02, 2020 at 08:49:51PM +0200, Kalle Valo wrote:
>> >> Thomas Krause <thomaskrause@posteo.de> writes:
>> >>
>> >> >> I had the same problem as well back in the days, for me enabling
>> >> >> CONFIG_IRQ_REMAP helped. If it helps for you also I wonder if we should
>> >> >> mention that in the ath11k warning above :)
Interrupt remapping only helps when the device supports only MSI (not
MSI-X) because x86 (kernel) does not support multiple MSI interrupts
without remapping.
So if only MSI is available then you get exactly _one_ MSI vector
without remapping.
>> >> > CONFIG_IRQ_REMAP did not do the trick.
The config alone does not help. The hardware has to support it and the
BIOS has to enable it.
Check the BIOS for a switch which is named 'VT-d' or such. It might
depend on 'Intel Virtualization Technology' or such.
>> > 00:1c.0 PCI bridge: Intel Corporation Device a0b8 (rev 20)
>> > Bus: primary=00, secondary=56, subordinate=56, sec-latency=0
>> > Memory behind bridge: 8c300000-8c3fffff [size=1M]
>> > 56:00.0 Network controller: Qualcomm Device 1101 (rev 01)
>> > Region 0: Memory at 8c300000 (64-bit, non-prefetchable) [size=1M]
So I grabbed the PCI info from the link and it has:
Capabilities: [50] MSI: Enable- Count=1/32 Maskable+ 64bit-
So no MSI-X, ergo only one MSI interrupt without remapping.
>> >> To summarise: Thomas is reporting[1] a problem with ath11k on QCA6390
>> >> PCI device where he is not having enough MSI vectors. ath11k needs 32
>> >> vectors but pci_alloc_irq_vectors() returns -ENOSPC. PCI support is new
>> >> for ath11k and introduced in v5.10-rc1. The irq allocation code is in
>> >> drivers/net/wireless/ath/ath11k/pci.c. [2]
>
>> > But it seems a little greedy if the device can't operate at all unless
>> > it gets 32 vectors. Are you sure that's a hard requirement? Most
>> > devices can work with fewer vectors, even if it reduces performance.
Right, even most high end network cards work with one interrupt.
>> This was my first reaction as well when I saw the code for the first
>> time. And the reply I got is that the firmware needs all 32 vectors, it
>> won't work with less.
Great design.
> I do see a couple other drivers that are completely inflexible (they
> request min==max). But I don't know the system constraint you're
> hitting. CC'd Thomas & Christoph in case they have time to give us a
> hint.
Can I have a full dmesg please?
Please enable CONFIG_IRQ_REMAP and CONFIG_INTEL_IOMMU (not strictly
required, but it's a Dell BIOS after all). Also set
CONFIG_INTEL_IOMMU_DEFAULT_ON.
Or simply try a distro kernel.
Thanks,
tglx
next prev parent reply other threads:[~2020-11-03 21:19 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <2849fd39-a7a6-8366-7c78-fc9fec4dffa4@posteo.de>
[not found] ` <87tuuqhc1i.fsf@codeaurora.org>
[not found] ` <1ce6f735-21ff-db7e-c8dc-d567761964aa@posteo.de>
2020-11-02 18:49 ` pci_alloc_irq_vectors fails ENOSPC for XPS 13 9310 Kalle Valo
2020-11-02 20:57 ` Bjorn Helgaas
2020-11-03 3:01 ` Carl Huang
2020-11-03 6:49 ` Kalle Valo
2020-11-03 16:08 ` Bjorn Helgaas
2020-11-03 21:08 ` Thomas Gleixner [this message]
2020-11-03 22:42 ` Thomas Gleixner
2020-11-09 18:44 ` Kalle Valo
[not found] ` <fa26ac8b-ed48-7ea3-c21b-b133532716b8@posteo.de>
2020-11-04 15:26 ` Thomas Gleixner
2020-11-05 13:23 ` Kalle Valo
2020-11-10 8:33 ` Kalle Valo
2020-11-11 8:53 ` Thomas Krause
2020-11-11 9:22 ` Kalle Valo
2020-11-11 19:10 ` Kalle Valo
2020-11-11 19:24 ` wi nk
2020-11-11 19:30 ` wi nk
2020-11-11 19:45 ` Kalle Valo
2020-11-11 20:12 ` wi nk
2020-11-11 21:35 ` Stefani Seibold
2020-11-11 22:02 ` Stefani Seibold
2020-11-12 0:24 ` wi nk
2020-11-12 1:10 ` wi nk
2020-11-12 1:11 ` wi nk
2020-11-12 2:31 ` wi nk
2020-11-12 6:29 ` Carl Huang
2020-11-12 7:05 ` Stefani Seibold
2020-11-12 7:15 ` Kalle Valo
2020-11-12 7:41 ` wi nk
2020-11-12 8:59 ` Kalle Valo
2020-11-12 15:44 ` wi nk
2020-11-13 9:52 ` wi nk
2020-11-15 13:30 ` Thomas Krause
2020-11-15 19:55 ` wi nk
2020-11-17 15:49 ` wi nk
2020-11-17 20:59 ` Thomas Gleixner
2020-11-18 10:22 ` wi nk
2020-11-11 9:39 ` Thomas Gleixner
2020-11-06 11:45 ` Devin Bayer
2020-11-09 18:48 ` Kalle Valo
2020-11-03 11:20 ` Devin Bayer
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