Re: [EXT] Re: [PATCH v1 3/4] serial: 8250_pci: Always try MSI/MSI-X

[Ralf Ramsauer]

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@xxxxxxxxxxxxxxxxx> wrote:
>>>> On 14/07/2021 15:35, Andy Shevchenko wrote:
>>>>> On Wed, Jul 14, 2021 at 3:56 PM Ralf Ramsauer
>>>>> <ralf.ramsauer@xxxxxxxxxxxxxxxxx> 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