On 26.02.2019 23:41, Bjorn Helgaas wrote: > Hi Heiner, > > On Fri, Feb 22, 2019 at 12:16 AM Heiner Kallweit <hkallweit1@xxxxxxxxx> wrote: >> >> I face the issue that a PCIe network chip misses RX packets if ASPM L1 >> sub-states are enabled. It seems that the RX FIFO is too small to buffer >> all incoming packets during ASPM exit latency. >> >> So far pci_disable_link_state() only allows to disable L1 completely. >> Would it make sense to extend this function to allow disabling >> L1 sub-states selectively? Looking at pcie_config_aspm_link() this >> seems to be possible. > > We could certainly explore the option of selectively disabling L1 substates. > > But before we do that, let's look at a couple things, because there > are some Linux issues in that area, and it's possible we could make a > generic fix that wouldn't require disabling the substates completely. > > One problem is the ASPM L1.2 state depends on LTR information, and we > don't support LTR correctly. There are a couple patches in -next to > fix some problems, but we still don't handle cases where the BIOS > doesn't program the LTR latencies and the LTR_L1.2_Threshold. > > Can you open a report at bugzilla.kernel.org and attach the complete > dmesg log (booted with "pci=earlydump") and the "sudo lspci -vvvxx" > output? > I have no system where I can reproduce the issue, it was reported by a user: https://bugzilla.redhat.com/show_bug.cgi?id=1671958 In comments 61 and 65 you find the lspci -vv output for the network chip. > Have you figured out which L1 substate specifically causes problems? > If not, maybe we can use setpci to fiddle with things manually and > narrow it down. > So far all I can say is that with ASPM disabled completely the issue doesn't occur. I'd have to see how to disable L1.2 only with setpci and then let the user test. > Bjorn > Heiner
