Re: PICe hotplug problems

[Joakim Tjernlund <joakim.tjernlund@transmode.se>]

yhlu.kernel@gmail.com wrote on 2012/07/11 03:33:05:
>
> On Tue, Jul 10, 2012 at 6:07 PM, Joakim Tjernlund
> <joakim.tjernlund@transmode.se> wrote:
> > yhlu.kernel@gmail.com wrote on 2012/07/11 00:09:00:
>
> >> No. Can you compile lspci util as static and run it ?
> >
> > That wasn't so hard so here:
> >
> > root@P2020RDB ~ # ./lspci  -vvxxx
> > 00:00.0 Class 0604: Device 1957:0079 (rev 21)
> >         Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
> >         Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
> >         Latency: 0, Cache Line Size: 32 bytes
> >         Region 0: Memory at <ignored> (32-bit, non-prefetchable)
> >         Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
> >         I/O behind bridge: 00000000-00000fff
> >         Memory behind bridge: 80000000-9fffffff
> >         Secondary status: 66MHz- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- <SERR- <PERR-
> >         BridgeCtl: Parity- SERR- NoISA- VGA- MAbort- >Reset- FastB2B-
> >                 PriDiscTmr- SecDiscTmr- DiscTmrStat- DiscTmrSERREn-
> >         Capabilities: [44] Power Management version 2
> >                 Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0+,D1+,D2+,D3hot+,D3cold+)
> >                 Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
> >         Capabilities: [4c] Express (v1) Root Port (Slot-), MSI 00
> >                 DevCap: MaxPayload 256 bytes, PhantFunc 0, Latency L0s <64ns, L1 <1us
> >                         ExtTag- RBE- FLReset-
> >                 DevCtl: Report errors: Correctable+ Non-Fatal+ Fatal+ Unsupported+
> >                         RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+
> >                         MaxPayload 128 bytes, MaxReadReq 512 bytes
> >                 DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend-
> >                 LnkCap: Port #0, Speed 2.5GT/s, Width x4, ASPM L0s, Latency L0 <2us, L1 unlimited
> >                         ClockPM- Surprise- LLActRep- BwNot-
> >                 LnkCtl: ASPM Disabled; RCB 128 bytes Disabled- Retrain- CommClk-
> >                         ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
> >                 LnkSta: Speed 2.5GT/s, Width x2, TrErr- Train- SlotClk- DLActive- BWMgmt- ABWMgmt-
> >                 RootCtl: ErrCorrectable- ErrNon-Fatal- ErrFatal- PMEIntEna- CRSVisible-
> >                 RootCap: CRSVisible-
> >                 RootSta: PME ReqID 0000, PMEStatus- PMEPending-
>
> There is no slot cap etc, so pciehp will not be loaded.
> the power of you child device can not be turned off/on.
>
> Not sure if can use link off/on make the clock effective.
>
> You can turn off and on the pcie link like following:
>
> 1. remove the child device
>      echo 1 > /sys/..../0000:01:00.0/remove
> 2. disable link
>      echo 1 > /sys/..../0000:00.00.0/pcie_link_disable
> 3. enable link
>      echo 1 > /sys/..../0000:00.00.0/pcie_link_disable
> 4. rescan the pci bus.
>      echo 1 > /sys/..../0000:00:00.0/rescan_bridge
>
> please check link disable patch at
> git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git
> for-pci-pcie-link
>
> | Subject: [PATCH] PCI: Add link_disable in /sysfs for pcie device
> |
> | Found PCIe cards from one vendor, will not respond to scan from bridge,
> | if we change bus number setting in bridge device.
> |
> | Have to do link disable/enable on the pcie root port.
> |
> |  So try to expose link disable bit of pcie link control register. We can use
> |  echo 1 > /sys/..../link_disable
> |  echo 0 > /sys/..../link_disable
> | to bring the pcie device back to respond to scan.

Sorry for the delay, got pulled into some high prio stuff.

Anyhow, I have backported your patch to 3.4 as we cannot upgrade easily and
I cannot make it work. I do

# > echo 1 > /sys/devices/pci0000:00/0000:00:00.0/pcie_link_disable
# > echo 0 > /sys/devices/pci0000:00/0000:00:00.0/pcie_link_disable
# > echo 1 > /sys/devices/pci0000:00/0000:00:00.0/rescan

# > lspci
00:00.0 Class 0604: Device 1957:0079 (rev 21)

#> dmesg
pcieport 0000:00:00.0: pcie_link_disable_set: lnk_ctrl = 18
pcieport 0000:00:00.0: pcie_link_disable_set: lnk_ctrl = 8

find /sys -name pcie_link_disable
find /sys -name remove
find /sys -name rescan

shows
/sys/devices/pci0000:00/0000:00:00.0/pcie_link_disable
/sys/devices/pci0000:00/0000:00:00.0/remove
/sys/bus/pci/rescan
/sys/devices/pci0000:00/0000:00:00.0/rescan
/sys/devices/pci0000:00/0000:00:00.0/pci_bus/0000:01/rescan
/sys/devices/pci0000:00/pci_bus/0000:00/rescan

so something is missing, but what?

 Jocke