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SubjectRe: [EXT] Re: [PATCH v1 3/4] serial: 8250_pci: Always try MSI/MSI-X
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On 16/07/2021 19:27, Andy Shevchenko wrote:
> On Fri, Jul 16, 2021 at 05:27:36PM +0200, Ralf Ramsauer wrote:
>> On 16/07/2021 17:01, Andy Shevchenko wrote:
>>> On Fri, Jul 16, 2021 at 4:07 PM Ralf Ramsauer
>>> <ralf.ramsauer@oth-regensburg.de> wrote:
>>>> On 14/07/2021 15:35, Andy Shevchenko wrote:
>>>>> On Wed, Jul 14, 2021 at 3:56 PM Ralf Ramsauer
>>>>> <ralf.ramsauer@oth-regensburg.de> wrote:
>>>>>> On 14/07/2021 08:54, Jiri Slaby wrote:
>>>>>>> On 13. 07. 21, 12:40, Andy Shevchenko wrote:
>>>>>
>>>>>>> Hmm, have you checked the commit which introduced the whitelist?
>>>>>>>
>>>>>>> Nevertheless, this needs to handled with care: while many 8250 devices
>>>>>>> actually claim to support MSI(-X) interrupts it should not be
>>>>>>> enabled be
>>>>>>> default. I had at least one device in my hands with broken MSI
>>>>>>> implementation.
>>>>>>>
>>>>>>> So better introduce a whitelist with devices that are known to support
>>>>>>> MSI(-X) interrupts. I tested all devices mentioned in the patch.
>>>>>>>
>>>>>>>
>>>>>>> You should have at least CCed the author for an input.
>>>>>>
>>>>>> Yep, back then I was testing three different 8250 pci cards. All of them
>>>>>> claimed to support MSI, while one really worked with MSI, the one that I
>>>>>> whitelisted. So I thought it would be better to use legacy IRQs as long
>>>>>> as no one tested a specific card to work with MSI.
>>>>>
>>>>> Can you shed a light eventually what those cards are?
>>>
>>>> So I found a no-name el-cheapo card that has some issues with MSI:
>>>
>>> Win Chip Head (WCH)
>>>
>>>> 18:00.0 Serial controller: Device 1c00:3253 (rev 10) (prog-if 05 [16850])
>
> Thank you!
>
> One more thing, ist it possible to see entire PCI configuration space (w/ or
> w/o MSI, I don't think it matters)? Something like
>
> `lspci -nk -vvv -xxx -s 18:0`
>
> to run.
>
> (I believe there are a lot of 0xff bytes)

Find it attached, w/ MSI+. Not that many, only the 0xffs for the MSI
mask, afaict.

Ralf
18:00.0 0700: 1c00:3253 (rev 10) (prog-if 05 [16850])
Subsystem: 1c00:3253
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
Interrupt: pin A routed to IRQ 104
NUMA node: 0
Region 0: I/O ports at 4000 [size=256]
Region 1: Memory at ab000000 (32-bit, prefetchable) [size=32K]
Region 2: I/O ports at 4100 [size=4]
Expansion ROM at ab200000 [disabled] [size=32K]
Capabilities: [60] Power Management version 3
Flags: PMEClk- DSI- D1- D2- AuxCurrent=375mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
Capabilities: [68] MSI: Enable+ Count=1/32 Maskable+ 64bit+
Address: 00000000fee000b8 Data: 0000
Masking: ffffffff Pending: 00000000
Capabilities: [80] Express (v2) Legacy Endpoint, MSI 00
DevCap: MaxPayload 256 bytes, PhantFunc 0, Latency L0s <2us, L1 <32us
ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
DevCtl: CorrErr- NonFatalErr+ FatalErr+ UnsupReq+
RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+
MaxPayload 256 bytes, MaxReadReq 512 bytes
DevSta: CorrErr- NonFatalErr- FatalErr- UnsupReq- AuxPwr+ TransPend-
LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s unlimited, L1 unlimited
ClockPM+ Surprise- LLActRep- BwNot- ASPMOptComp-
LnkCtl: ASPM Disabled; RCB 64 bytes, Disabled- CommClk+
ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
LnkSta: Speed 2.5GT/s (ok), Width x1 (ok)
TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
DevCap2: Completion Timeout: Not Supported, TimeoutDis+ NROPrPrP- LTR-
10BitTagComp- 10BitTagReq- OBFF Not Supported, ExtFmt- EETLPPrefix-
EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
FRS-
AtomicOpsCap: 32bit- 64bit- 128bitCAS-
DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis- LTR- OBFF Disabled,
AtomicOpsCtl: ReqEn-
LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
Compliance De-emphasis: -6dB
LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete- EqualizationPhase1-
EqualizationPhase2- EqualizationPhase3- LinkEqualizationRequest-
Retimer- 2Retimers- CrosslinkRes: unsupported
Capabilities: [100 v1] Advanced Error Reporting
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- AdvNonFatalErr-
CEMsk: RxErr+ BadTLP+ BadDLLP+ Rollover+ Timeout+ AdvNonFatalErr+
AERCap: First Error Pointer: 00, ECRCGenCap+ ECRCGenEn+ ECRCChkCap+ ECRCChkEn+
MultHdrRecCap- MultHdrRecEn- TLPPfxPres- HdrLogCap-
HeaderLog: 00000000 00000000 00000000 00000000
Kernel driver in use: serial
Kernel modules: 8250_pci
00: 00 1c 53 32 07 04 10 00 10 05 00 07 00 00 00 00
10: 01 40 00 00 08 00 00 ab 01 41 00 00 00 00 00 00
20: 00 00 00 00 00 00 00 00 00 00 00 00 00 1c 53 32
30: 00 80 ff ff 60 00 00 00 00 00 00 00 ff 01 00 00
40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
60: 01 68 c3 c9 00 00 00 00 05 80 8b 01 b8 00 e0 fe
70: 00 00 00 00 00 00 00 00 ff ff ff ff 00 00 00 00
80: 10 00 12 00 41 8b 64 00 3e 28 10 00 11 fc 07 00
90: 40 00 11 10 00 00 00 00 00 00 00 00 00 00 00 00
a0: 00 00 00 00 10 00 00 00 00 00 00 00 00 00 00 00
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

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