+ Ben Chuang <ben.chuang@xxxxxxxxxxxxxxxxxxx> It does not look like that driver allows runtime pm. On 22/05/20 7:16 pm, larsh@xxxxxxxxxx wrote: > Relevant logs: > > May 21 23:05:31 host kernel: sdhci-pci 0000:53:00.0: SDHCI controller found [17a0:9755] (rev 0) > May 21 23:05:31 host kernel: sdhci-pci 0000:53:00.0: enabling device (0000 -> 0002) > May 21 23:05:31 host kernel: mmc0: SDHCI controller on PCI [0000:53:00.0] using ADMA 64-bit > > > > On Friday, May 22, 2020, 1:59:08 AM PDT, Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote: > > > > > > +Cc: Adrian > > On Fri, May 22, 2020 at 9:15 AM larsh@xxxxxxxxxx <larsh@xxxxxxxxxx> wrote: >> >> Thanks David! >> >> With this I tracked down the SD Card Reader (Genesys Logic, Inc Device 9755) as the culprit. >> These are standard in many ThinkPads. >> The curious part is that resume from suspend (S3 or S0iX) also fixes the problem. >> Looks like the driver is not initializing correctly at boot time. >> >> Transcript: >> >> $ cat /sys/kernel/debug/pmc_core/ltr_show | grep SOUTHPORT >> SOUTHPORT_A LTR: RAW: 0x88018c01 Non-Snoop(ns): 1024 Snoop(ns): 32768 >> SOUTHPORT_B LTR: RAW: 0x0 Non-Snoop(ns): 0 Snoop(ns): 0 >> SOUTHPORT_C LTR: RAW: 0x9f409f4 Non-Snoop(ns): 0 Snoop(ns): 0 >> SOUTHPORT_D LTR: RAW: 0x88aa88aa Non-Snoop(ns): 174080 Snoop(ns): 174080 >> SOUTHPORT_E LTR: RAW: 0x0 Non-Snoop(ns): 0 Snoop(ns): 0 >> >> $ lspci -t >> -[0000:00]-+-00.0 >> +-01.0-[01]--+-00.0 >> | \-00.1 >> +-02.0 >> +-04.0 >> +-08.0 >> +-12.0 >> +-14.0 >> +-14.2 >> +-15.0 >> +-16.0 >> +-1c.0-[53]----00.0 >> +-1d.0-[02]----00.0 >> +-1d.6-[52]----00.0 >> +-1e.0 >> +-1f.0 >> +-1f.3 >> +-1f.4 >> +-1f.5 >> \-1f.6 >> >> $ lspci | grep 53 >> 53:00.0 SD Host controller: Genesys Logic, Inc Device 9755 >> >> $ cat /sys/bus/pci/devices/0000\:53\:00.0/power/control >> auto >> >> $ echo 1 > /sys/bus/pci/devices/0000\:53\:00.0/remove >> 1 >> >> $ cat /sys/kernel/debug/pmc_core/ltr_show | grep SOUTHPORT >> SOUTHPORT_A LTR: RAW: 0x8010c01 Non-Snoop(ns): 0 Snoop(ns): 0 >> SOUTHPORT_B LTR: RAW: 0x0 Non-Snoop(ns): 0 Snoop(ns): 0 >> SOUTHPORT_C LTR: RAW: 0x9f409f4 Non-Snoop(ns): 0 Snoop(ns): 0 >> SOUTHPORT_D LTR: RAW: 0x8c548c54 Non-Snoop(ns): 2752512 Snoop(ns): 2752512 >> SOUTHPORT_E LTR: RAW: 0x0 Non-Snoop(ns): 0 Snoop(ns): 0 >> >> Cheers. >> >> -- Lars >> >> >> >> >> >> >> >> >> On Tuesday, May 19, 2020, 9:03:53 AM PDT, David E. Box <david.e.box@xxxxxxxxxxxxxxx> wrote: >> >> >> >> >> >>>>> Does anybody know what's going on or how to debug this further? >>>>> As stated above, I was able to work around this problem by >>>>> ignoring SOUTHPORT_A via /sys/kernel/debug/pmc_core/ltr_ignore. >>>>> There has to be a better way, and I'm sure I'm not the only one >>>>> running into this. >> >> ltr_show shows the PMC's (Power Management Controller) view of SoC >> devices and busses. The SOUTHPORTs are the PCIe root ports on your >> system. When you run lspci they are the PCI bridges. Generally, the >> bridges are enumerated in the same order as the SOUTHPORTs, so >> SOUTHPORT_A is your first bridge and the device attached to it (shown >> in lspci -t) is the device that was blocking deeper PC states according >> to your debug. >> >> Determine what this device is on your system. If the ltr was low it's >> because that is what the device requested. You should first check that >> runtime pm is enabled for the device. To do this, check the control >> file in /sys/bus/pci/devices/<SSSS:BB:DD.F>/power, where SSSS:BB:DD.F >> is the enumeration of your device as shown in lspci. If it is 'on' then >> runtime pm is disabled. To enable it echo 'auto' into the file with >> root privileges. Enabling runtime pm should allow the driver to reduce >> functionality of the device when idle. This should lead to a larger >> latency request on the PCI bus which should be reflected in ltr_show. >> You can see if the device is actually runtime suspended and how much >> time it's been suspended (or active) by reading the associated files in >> the power folder. >> >> If this doesn't work, then it's possible that your device doesn't >> support runtime pm. This may be purposely for reliability reasons or >> the driver may just lack support. Check forums discussing issues with >> the device and look for possible options in the driver to force pm >> support (generally this will be centered around enabling ASPM). >> >> You can also download powertop to see the package c-state residencies >> more clearly as percentages of time. powertop also has a tunables tab >> that will show the status of runtime pm on all devices on the system >> and allow you to enable them individually. >> >> >> David > >> > >
