On Wed, 17 Mar 2021 17:45:49 -0500 Bjorn Helgaas helgaas@kernel.org wrote:
[+cc Zachary, author of 8a3ebd8de328]
Thanks for the report and the patch, Marek!
On Wed, Mar 17, 2021 at 12:59:24PM +0100, Marek Behún wrote:
The ASMedia ASM1062 SATA controller causes an External Abort on controllers which support Max Payload Size >= 512. It happens with Aardvark PCIe controller (tested on Turris MOX) and also with DesignWare controller (armada8k, tested on CN9130-CRB):
ata1: SATA link up 6.0 Gbps (SStatus 133 SControl 300) ata1.00: ATA-9: WDC WD40EFRX-68WT0N0, 80.00A80, max UDMA/133 ata1.00: 7814037168 sectors, multi 0: LBA48 NCQ (depth 32), AA ERROR: Unhandled External Abort received on 0x80000000 at EL3! ERROR: exception reason=1 syndrome=0x92000210 PANIC at PC : 0x00000000040273bc
Limiting Max Payload Size to 256 bytes solves this problem.
On Turris MOX this problem first appeared when the pci-aardvark controller started using the pci-emul-bridge API, in commit 8a3ebd8de328 ("PCI: aardvark: Implement emulated root PCI bridge config space").
Any ideas about why 8a3ebd8de328 made a difference? Could there be a defect in 8a3ebd8de328? Or maybe before 8a3ebd8de328 we didn't actually read or update MPS settings in the hardware?
Before 8a3ebd8de328 the PCIe subsystem could not detect that the MPS is 512 bytes, because the emulated bridge did not exists. So it did not try to change MPS for the SATA controller, or changed it to minimum of 128 bytes. Once pci-emul-bridge was added, the PCIe subsystem had access to the information that the aardvark controller supports 512 bytes, so it tried to leverage it, since the SATA controller says it can handle 512 bytes MPS. But apparently it cannot.
On armada8k this was always a problem because it has HW root bridge.
Can you please open a report at bugzilla.kernel.org and attach the complete "sudo lspci -vv" output for both systems? I think it's OK to collect these with the patch applied; we should still be able to see the information we use to compute the MPS values. But please include the CONFIG_PCIE_BUS_* settings and any "pcie_bus_*" kernel command line arguments.
This quirk suggests that there's a hardware defect in the ASMedia ASM1062. But if that's really the case, we should see reports on lots of platforms, and I'm only aware of these two. You do mention that it was always a problem on armada8k; if you know of other reports of that, please include URLs in the bugzilla.
I think that most people use this adapter on x86 platforms. Maybe x86 PCIe controllers do not support 512 bytes MPS (at least my notebook nor work computer don't). So this issue would be only detected by someone who used this controller on a controller which supports 512+ bytes MPS. armada8k is mainly used for network devices, so PCIe there is probably mostly used for wifi cards, and for SATA armada8k has native controller, and also nVME. The most probable answer is that noone used this controller on armada8k nor aardvark...
If the problem only occurs on these platforms, my first guess would be a hardware defect in these platforms or a software defect in the PCIe controller driver. It wouldn't surprise me if we have a generic PCI core defect in how we set MPS, either.
If someone has this card and a x86 or other PCIe controller capable of 512 byte MPS, maybe they could check.
But aramda8k PCIe controller (which is a DesignWare IP) is completely different from aardvark (although they both are on Armada SOCs). I think it is more probable that the problem is in the ASMedia SATA controller, this controller has also other issues (firmware sometimes crashing, for example).
Signed-off-by: Marek Behún kabel@kernel.org Reported-by: Rötti espressobinboardarmbiantempmailaddress@posteo.de Cc: Pali Rohár pali@kernel.org Cc: stable@vger.kernel.org
drivers/pci/quirks.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index 653660e3ba9e..a561136efb08 100644 --- a/drivers/pci/quirks.c +++ b/drivers/pci/quirks.c @@ -3251,6 +3251,11 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_SOLARFLARE, PCI_DEVICE_ID_SOLARFLARE_SFC4000A_1, fixup_mpss_256); DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_SOLARFLARE, PCI_DEVICE_ID_SOLARFLARE_SFC4000B, fixup_mpss_256); +/*
- For some reason DECLARE_PCI_FIXUP_HEADER does not work with pci-aardvark
- controller. We have to use DECLARE_PCI_FIXUP_EARLY.
- */
This is curious, too. If we need the quirk, I'd like to run this down to figure out why we need an EARLY instead of HEADER quirk. Differences like that suggest a bug elsewhere, or at least an unnecessary difference between PCIe controller drivers.
Now that I look at this, the comment is wrong. What I meant to say is that when I used HEADER quirk, the PCIe subsystem did change the MPS to 512 bytes, so clearly the HAEDER quirk only comes after changing of MPS.
I think that the other quirks using the fixup_mpss_256 callback should also use EARLY instead of HEADER. Maybe something changed in PCI API sometime and noone noticed that these quirks stopped working?
Marek
+DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_ASMEDIA, 0x0612, fixup_mpss_256); /*
- Intel 5000 and 5100 Memory controllers have an erratum with read completion
-- 2.26.2