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Message-ID: <979A8436335E3744ADCD3A9F2A2B68A52AD13FB9@SJEXCHMB10.corp.ad.broadcom.com>
Date: Tue, 27 Aug 2013 07:40:17 +0000
From: "Yuval Mintz" <yuvalmin@...adcom.com>
To: "Bjorn Helgaas" <bhelgaas@...gle.com>
cc: "jacob.e.keller@...el.com" <jacob.e.keller@...el.com>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: pcie_get_minimum_link returns 0 width
> On Mon, Aug 26, 2013 at 5:36 PM, Yuval Mintz <yuvalmin@...adcom.com>
> wrote:
> >> > Hi,
> >> >
> >> > I tried adding support for the newly added 'pcie_get_minimum_link' into
> >> the
> >> > bnx2x driver, but found out the some of my devices started showing
> width
> >> x0.
> >> >
> >> > By adding debug prints, I've found out there were devices up the chain
> that
> >> > Showed 0 when their PCI_EXP_LNKSTA was read by said function.
> >> > However, when I tried looking via lspci the output claimed the width was
> >> x4.
> Looking at its implementation, one obvious difference is that
> pcie_get_minimum_link() traverses up the hierarchy and keeps track of
> the minimum values it finds. lspci, on the other hand, just reads
> PCI_EXP_LNKSTA from a single device and decodes it.
>
> You said lspci reports x4 for every device from the Root Port all the
> way down to your NIC, so I would think the minimum from
> pcie_get_minimum_link() would be x4. But apparently it's not. Maybe
> there's a bug in it. Can you post the complete "lspci -vv" output
> along with your debug patch and output?
>
> Bjorn
Here's the patch:
---
drivers/pci/pci.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index c71e78c..72cb87b 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3601,13 +3601,19 @@ int pcie_get_minimum_link(struct pci_dev *dev, enum pci_bus_speed *speed,
enum pcie_link_width next_width;
ret = pcie_capability_read_word(dev, PCI_EXP_LNKSTA, &lnksta);
- if (ret)
+ if (ret) {
+ printk(KERN_ERR "Failed to Read LNKSTA\n");
return ret;
+ }
next_speed = pcie_link_speed[lnksta & PCI_EXP_LNKSTA_CLS];
next_width = (lnksta & PCI_EXP_LNKSTA_NLW) >>
PCI_EXP_LNKSTA_NLW_SHIFT;
+ printk(KERN_ERR "LnkSta %04x [%04x:%02x.%02x]\n",
+ lnksta, dev->bus->number, PCI_SLOT(dev->devfn),
+ PCI_FUNC(dev->devfn));
+
if (next_speed < *speed)
*speed = next_speed;
--
1.7.1
And here are the lscpi results for 09:00.0 and 0a:01.0
(The two devices for which the loop returns 0 width):
Sysfs do read [Pos 0, len 64]
09:00.0 Class 0604: Device 8086:3500 (rev 01)
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: 64 bytes
Bus: primary=09, secondary=0a, subordinate=11, sec-latency=0
Memory behind bridge: fb800000-fd7fffff
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: Sysfs do read [Pos 68, len 4]
[44] Express (v1) Upstream Port, MSI 00
Sysfs do read [Pos 72, len 16]
DevCap: MaxPayload 256 bytes, PhantFunc 0, Latency L0s <64ns, L1 <1us
ExtTag- AttnBtn- AttnInd- PwrInd- RBE- FLReset-SlotPowerLimit 0.000W
DevCtl: Report errors: Correctable- Non-Fatal+ Fatal+ Unsupported-
RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop-
MaxPayload 256 bytes, MaxReadReq 4096 bytes
DevSta: CorrErr- UncorrErr- FatalErr+ UnsuppReq+ AuxPwr- TransPend-
LnkCap: Port #0, Speed 2.5GT/s, Width x8, ASPM L0s, Latency L0 unlimited, L1 unlimited
ClockPM- Surprise- LLActRep- BwNot-
LnkCtl: ASPM Disabled; Disabled- Retrain- CommClk-
ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
LnkSta: Speed 2.5GT/s, Width x4, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
Capabilities: Sysfs do read [Pos 112, len 4]
[70] Power Management version 2
Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
Sysfs do read [Pos 116, len 4]
Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
Capabilities: Sysfs do read [Pos 128, len 4]
[80] Sysfs do read [Pos 132, len 4]
Subsystem: Device 0000:0000
Sysfs do read [Pos 256, len 4]
Capabilities: [100 v1] Advanced Error Reporting
Sysfs do read [Pos 260, len 24]
UESta: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq+ ACSViol-
UEMsk: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq+ ACSViol-
UESvrt: DLP+ SDES- TLP+ FCP+ CmpltTO+ CmpltAbrt+ UnxCmplt+ RxOF+ MalfTLP+ ECRC- UnsupReq+ ACSViol-
CESta: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr-
CEMsk: RxErr+ BadTLP+ BadDLLP+ Rollover+ Timeout+ NonFatalErr-
AERCap: First Error Pointer: 14, GenCap- CGenEn- ChkCap- ChkEn-
Kernel driver in use: pcieport
Kernel modules: shpchp
Sysfs do read [Pos 0, len 64]
0a:01.0 Class 0604: Device 8086:3514 (rev 01)
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: 64 bytes
Bus: primary=0a, secondary=0e, subordinate=10, sec-latency=0
Memory behind bridge: fb800000-fd7fffff
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: Sysfs do read [Pos 68, len 4]
[44] Express (v1) Downstream Port (Slot-), MSI 00
Sysfs do read [Pos 72, len 16]
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 256 bytes, MaxReadReq 4096 bytes
DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend-
LnkCap: Port #2, Speed 2.5GT/s, Width x4, ASPM L0s, Latency L0 unlimited, L1 unlimited
ClockPM- Surprise- LLActRep- BwNot-
LnkCtl: ASPM Disabled; Disabled- Retrain- CommClk-
ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
LnkSta: Speed 2.5GT/s, Width x4, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
Capabilities: Sysfs do read [Pos 96, len 4]
[60] MSI: Enable- Count=1/1 Maskable- 64bit+
Sysfs do read [Pos 100, len 10]
Address: 0000000000000000 Data: 0000
Capabilities: Sysfs do read [Pos 112, len 4]
[70] Power Management version 2
Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
Sysfs do read [Pos 116, len 4]
Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
Capabilities: Sysfs do read [Pos 128, len 4]
[80] Sysfs do read [Pos 132, len 4]
Subsystem: Device 0000:0000
Sysfs do read [Pos 256, len 4]
Capabilities: [100 v1] Advanced Error Reporting
Sysfs do read [Pos 260, len 24]
UESta: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
UEMsk: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq+ ACSViol-
UESvrt: DLP+ SDES- TLP+ FCP+ CmpltTO+ CmpltAbrt+ UnxCmplt+ RxOF+ MalfTLP+ ECRC- UnsupReq+ ACSViol-
CESta: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr-
CEMsk: RxErr+ BadTLP+ BadDLLP+ Rollover+ Timeout+ NonFatalErr-
AERCap: First Error Pointer: 00, GenCap- CGenEn- ChkCap- ChkEn-
Kernel driver in use: pcieport
Kernel modules: shpchp
Thanks,
Yuval
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