>> This e-mail is a follow-up as requested in this bug[1]. I will repost
>> everything so far in this e-mail. Please CC me as I'm not subscribed
>> to your list.
>>
>> Current head gives this when I plug a 'Mass Storage Device' into a 2.0 hub:
>>
>> [ 842.760400] hub 1-0:1.0: unable to enumerate USB device on port 3
>> [ 843.080058] usb 1-3: new high-speed USB device number 48 using ehci-pci
>> [ 858.230072] usb 1-3: device descriptor read/64, error -110
>> [ 873.490070] usb 1-3: device descriptor read/64, error -110
>>
>> Reverting the following commit makes it work again:
>>
>> commit 55bcdce8a8228223ec4d17d8ded8134ed265d2c5
>> Author: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
>> Date: Fri Jan 25 16:52:45 2013 -0500
>>
>> USB: EHCI: remove ASS/PSS polling timeout
>>
>> This patch (as1647) attempts to work around a problem that seems to
>> affect some nVidia EHCI controllers. They sometimes take a very long
>> time to turn off their async or periodic schedules. I don't know if
>> this is a result of other problems, but in any case it seems wise not
>> to depend on schedule enables or disables taking effect in any
>> specific length of time.
>>
>> The patch removes the existing 20-ms timeout for enabling and
>> disabling the schedules. The driver will now continue to poll the
>> schedule state at 1-ms intervals until the controller finally decides
>> to obey the most recent command issued by the driver. Just in case
>> this hides a problem, a debugging message will be logged if the
>> controller takes longer than 20 polls.
>>
>> I don't know if this will actually fix anything, but it can't hurt.
>>
>> Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
>> Tested-by: Piergiorgio Sartor <piergiorgio.sartor@xxxxxxxx>
>> CC: <stable@xxxxxxxxxxxxxxx>
>> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>>
>> diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
>> index 20dbdcb..f904071 100644
>> --- a/drivers/usb/host/ehci-timer.c
>> +++ b/drivers/usb/host/ehci-timer.c
>> @@ -113,14 +113,15 @@ static void ehci_poll_ASS(struct ehci_hcd *ehci)
>>
>> if (want != actual) {
>>
>> - /* Poll again later, but give up after about 20 ms */
>> - if (ehci->ASS_poll_count++ < 20) {
>> - ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
>> - return;
>> - }
>> - ehci_dbg(ehci, "Waited too long for the async schedule
>> status(%x/%x), giving up\n",
>> - want, actual);
>> + /* Poll again later */
>> + ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
>> + ++ehci->ASS_poll_count;
>> + return;
>> }
>> +
>> + if (ehci->PSS_poll_count > 20)
>> + ehci_dbg(ehci, "PSS poll count reached %d\n",
>> + ehci->PSS_poll_count);
>> ehci->PSS_poll_count = 0;
>>
>> /* The status is up-to-date; restart or stop the schedule as needed */
>>
>> Please note, that I'm using the 'irqpoll' cmdline to improve system
>> stability. What I forgot to mention in the bug was the chipset:
>>
>> 00:10.3 USB controller: VIA Technologies, Inc. USB 2.0 (rev 82)
>> (prog-if 20 [EHCI])
>> Subsystem: Micro-Star International Co., Ltd. KT4AV motherboard
>> Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV+ VGASnoop- ParErr-
>> Stepping- SERR- FastB2B- DisINTx-
>> Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort-
>> <TAbort- <MAbort- >SERR- <PERR- INTx-
>> Latency: 32, Cache Line Size: 32 bytes
>> Interrupt: pin D routed to IRQ 21
>> Region 0: Memory at dffeff00 (32-bit, non-prefetchable) [size=256]
>> Capabilities: [80] Power Management version 2
>> Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=375mA PME(D0+,D1+,D2+,D3hot+,D3cold+)
>> Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
>> Kernel driver in use: ehci-pci
>>
>> Yes, it's 10 years old, and no I'm not scrooge. We are waiting a while
>> for computer prices to plummet mkay?
>>
>> [1]: https://bugzilla.kernel.org/show_bug.cgi?id=54031
>
> Would like to add that while searching the mailing lists I stumbled on this:
>
> http://marc.info/?l=linux-usb&m=136045531311402&w=4
>
> It's an entirely seperate USB issue in this cycle. The person is doing
> git bisect to find the regression. I did another approach as
> recompiling the full kernel on a 1,25GHz isn't even remotely funny
> anymore.
>
> On top of HEAD I started reverting groups of USB EHCI patches one by
> one. I'm just mentioning it since I'm not sure if this procedure is
> accepted here.
Did some more testing this morning. It seems like it's a race
condition, which somewhat confirms that this patch is involved. Just
had an occurance where the kernel with this patch *not* reverted
handled the USB just fine. But subsequent attempts failed like this:
# attempt 2
[ 382.370377] hub 1-0:1.0: unable to enumerate USB device on port 3
[ 382.690046] usb 1-3: new high-speed USB device number 7 using ehci-pci
[ 397.840031] usb 1-3: device descriptor read/64, error -110
# attempt 3
[ 413.040329] hub 1-0:1.0: unable to enumerate USB device on port 3
[ 413.360069] usb 1-3: new high-speed USB device number 8 using ehci-pci
[ 428.510049] usb 1-3: device descriptor read/64, error -110
Please note the ~15 second time-out between detection and error. This
also explains what made ordinary bisect somewhat 'tedious'... . Kernel
with this patch reverted handles the USB solidly everytime and on
every subsequent occurance so far.
The 'bad' kernel handles the USB correctly every once in a while. But
subsequent occurances always failed so far under these conditions.
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