On 28.11.2018 18:50, Lucas Stach wrote: > Am Mittwoch, den 28.11.2018, 18:36 +0100 schrieb Stefan Agner: >> On 28.11.2018 13:19, Stefan Agner wrote: >> > On 21.11.2018 14:47, Leonard Crestez wrote: >> > > On 11/20/2018 11:28 PM, Trent Piepho wrote: >> > > > On Tue, 2018-11-20 at 21:42 +0100, Stefan Agner wrote: >> > > > > On 20.11.2018 20:13, Trent Piepho wrote: >> > > > > > It also seems to me that this doesn't need to be in the internal pci >> > > > > > config access functions. The driver shouldn't be reading registers >> > > > > > that don't exist anyway. It's really about trying to fix sysfs access >> > > > > > to registers that don't exist. So maybe it should be done there. >> > > > > >> > > > > That was my first approach, see: >> > > > >> > > > Yes, but that just used the pci device id which applies to every IMX >> > > > design. >> > > > >> > > > It's also not totally correct, as it seems real registers after 0x200 >> > > > do work on imx6, and that would prevent access to them. >> > > >> > > I see that Lorenzo already accepted the patch in pci/dwc: >> > > >> > > https://git.kernel.org/pub/scm/linux/kernel/git/lpieralisi/pci.git/commit/?h=pci/dwc&id=f14eaec153aaebbe940ddd21e4198cc2abc927c2 >> > > >> > > My tests show that this series breaks pci cards on 6qdl and I think it >> > > should be reverted until a fix is found. Are you OK with this? >> > > >> > > Fixing might require an entirely different approach. >> > >> > I tried to reproduce this issue on Apalis iMX6 (i.MX 6Q) with a ath9k >> > PCIe WiFi card, the issue you are seeing did not happen. My lspci looks >> > as follows: >> > >> > root@ea210c63d739:/# 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 255 >> > Memory at 01000000 (32-bit, non-prefetchable) [size=1M] >> > Bus: primary=00, secondary=01, subordinate=ff, sec-latency=0 >> > Memory behind bridge: 01100000-011fffff >> > [virtual] Expansion ROM at 01200000 [disabled] [size=64K] >> > Capabilities: [40] Power Management version 3 >> > Capabilities: [50] MSI: Enable- Count=1/1 Maskable+ 64bit+ >> > Capabilities: [70] Express Root Port (Slot-), MSI 00 >> > Capabilities: [100] Advanced Error Reporting >> > Capabilities: [140] Virtual Channel >> > lspci: Unable to load libkmod resources: error -12 >> > >> > 01:00.0 Network controller: Qualcomm Atheros AR928X Wireless Network >> > Adapter (PCI-Express) (rev 01) >> > Subsystem: Foxconn International, Inc. Device e007 >> > Flags: bus master, fast devsel, latency 0, IRQ 312 >> > Memory at 01100000 (64-bit, non-prefetchable) [size=64K] >> > Capabilities: [40] Power Management version 2 >> > Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit- >> > Capabilities: [60] Express Legacy Endpoint, MSI 00 >> > Capabilities: [90] MSI-X: Enable- Count=1 Masked- >> > Capabilities: [100] Advanced Error Reporting >> > Capabilities: [140] Virtual Channel >> > Capabilities: [160] Device Serial Number 00-00-00-00-00-00-00-00 >> > Kernel driver in use: ath9k >> > >> > >> > I did also setup a WiFi network and transmitted some packages, but I did >> > not get a nobody carred message. Do you have an idea why that might be? >> > >> > # cat /proc/interrupts >> > ... >> > 312: 10967 0 0 0 GPC 123 Level >> > ath9k >> > ... >> > >> > >> > Your conclusion in this thread seem reasonable, hence reverting the >> > issue does. However, I still would like to reproduce the issue so I can >> > make sure that future patches don't break it :-) >> >> Hm, I realized that I need to enable CONFIG_PCIEPORTBUS and set >> ath9k.use_msi=1 to get MSI for that card. However, it seems that ath9k >> does not behave well in that setup. It does get interrupts, and seems to >> work to some degree, but I was not successful in transmitting data over >> WiFi, but that might be an entirly different thing. >> >> However, what I noticed is that when CONFIG_PCIEPORTBUS and >> CONFIG_PCI_MSI is enabled, MSI works but legacy interrupt seem not to >> fire anymore. That is true for ath9k as well as e1000e (using >> e1000e.IntMode=0 to force legacy). Is that a known issue/limitation with >> i.MX 6 PCIe? > > Yes, this is a known issue with the Designware PCIe core, not just on > i.MX6. As soon as any MSI interrupt is enabled, the core doesn't > forward legacy IRQs anymore. Oh I see, unfortunate! > > So if any card in your system needs legacy interrupts (and ath9k is > very likely to need this, as MSI support is pretty new and > experimental), you need to boot with "nomsi" set on the kernel command > line. Ok, thanks for clarification. FWIW, e1000e with MSI works perfectly fine, its just ath9k when forcing MSI using the kernel parameter which does not work really. I guess that is the reason it is not enabled by default. -- Stefan
