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From: Ferry Toth <fntoth@gmail.com>
To: Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
	Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Felipe Balbi <balbi@kernel.org>,
	Alan Stern <stern@rowland.harvard.edu>,
	USB <linux-usb@vger.kernel.org>
Subject: Re: USB network gadget / DWC3 issue
Date: Sat, 10 Apr 2021 16:08:00 +0200	[thread overview]
Message-ID: <0ba7a6ba-e6a7-9cd4-0695-64fc927e01f1@gmail.com> (raw)
In-Reply-To: <2c5bf7f3-14b6-797f-ab5d-039081906815@gmail.com>

Hi, some corrections below.

Op 10-04-2021 om 15:29 schreef Ferry Toth:
> Op 09-04-2021 om 15:26 schreef Ferry Toth:
>> Hi,
>>
>> Op 08-04-2021 om 23:12 schreef Thinh Nguyen:
>>> Ferry Toth wrote:
>>>> Op 07-04-2021 om 15:34 schreef Andy Shevchenko:
>>>>> On Wed, Apr 7, 2021 at 3:24 AM Thinh Nguyen
>>>>> <Thinh.Nguyen@synopsys.com> wrote:
>>>>>> Thinh Nguyen wrote:
>>>>> ...
>>>>>
>>>>>>> I took a look at the "bad" and "normal" tracepoints. There are a 
>>>>>>> few
>>>>>>> 1-second delays where the host tried to bring the device back and
>>>>>>> resume from low power:
>>>>>>>
>>>>>>>        ksoftirqd/0-10      [000] d.s.   231.501808:
>>>>>>> dwc3_gadget_ep_cmd: ep3in: cmd 'Update Transfer' [60007] params
>>>>>>> 00000000 00000000 00000000 --> status: Successful
>>>>>>>        ksoftirqd/0-10      [000] d.s.   231.501809: dwc3_readl: 
>>>>>>> addr
>>>>>>> 00000000d68ecd36 value 0000a610
>>>>>>>        ksoftirqd/0-10      [000] d.s.   231.501810: dwc3_writel: 
>>>>>>> addr
>>>>>>> 00000000d68ecd36 value 0000a710
>>>>>>>             <idle>-0       [000] d.h. 232.499418: dwc3_readl: addr
>>>>>>> 00000000a15e0e35 value 00000034
>>>>>>>             <idle>-0       [000] d.h. 232.499423: dwc3_readl: addr
>>>>>>> 00000000bb67b585 value 00001000
>>>>>>>             <idle>-0       [000] d.h. 232.499425: dwc3_writel: addr
>>>>>>> 00000000bb67b585 value 80001000
>>>>>>>             <idle>-0       [000] d.h. 232.499427: dwc3_writel: addr
>>>>>>> 00000000a15e0e35 value 00000034
>>>>>>>        irq/15-dwc3-476     [000] d...   232.499480: dwc3_event: 
>>>>>>> event
>>>>>>> (00000401): WakeUp [U0]
>>>>>>>        irq/15-dwc3-476     [000] d...   232.499492: dwc3_event: 
>>>>>>> event
>>>>>>> (00000401): WakeUp [U0]
>>>>>>>        irq/15-dwc3-476     [000] d...   232.499496: dwc3_event: 
>>>>>>> event
>>>>>>> (00006088): ep2out: Transfer In Progress [0] (SIm)
>>>>>>>        irq/15-dwc3-476     [000] d...   232.499501:
>>>>>>> dwc3_complete_trb: ep2out: trb 00000000c7ce524e (E179:D170) buf
>>>>>>> 0000000008273540 size 1463 ctrl 00000818 (hlcS:sC:normal)
>>>>>>>        irq/15-dwc3-476     [000] d...   232.499518:
>>>>>>> dwc3_gadget_giveback: ep2out: req 0000000012e296cf length 73/1536
>>>>>>> zsI ==> 0
>>>>>>>        irq/15-dwc3-476     [000] d...   232.499562: dwc3_ep_queue:
>>>>>>> ep2out: req 0000000012e296cf length 0/1536 zsI ==> -115
>>>>>>>        irq/15-dwc3-476     [000] d...   232.499601: 
>>>>>>> dwc3_prepare_trb:
>>>>>>> ep2out: trb 000000008c083777 (E180:D170) buf 0000000002a7e9c0 size
>>>>>>> 1536 ctrl 00000819 (HlcS:sC:normal)
>>>>>>>
>>>>>>>
>>>>>>> Your device is operating in highspeed right? Try to turn off LPM 
>>>>>>> from
>>>>>>> host and see if that helps with the speed throttling issue. (If 
>>>>>>> you're
>>>>>>> using xHCI host, then set XHCI_HW_LPM_DISABLE). It may also help 
>>>>>>> with
>>>>>>> the connection issue you saw.
>>>>>>>
>>>>>>> It seems to be an issue from host, but I can't tell for sure 
>>>>>>> unless we
>>>>>>> have some USB traffic analyzer that shows what's going on. Have you
>>>>>>> tried different hosts?
>>>>>>>
>>>>>> You can also disable LPM from the gadget side by setting
>>>>>> dwc->dis_enblslpm_quirk.
>>>>> Ferry, it can be done by adding a corresponding property to the
>>>>> dwc3-pci.c for Intel Merrifield platform. I'll check also for my case
>>>>> and perhaps I can collect some traces in my case later on when I have
>>>>> more time for that.
>>>>>
>>>> Ok thanks all. Here is what I tried:
>>>>
>>>> Another computer (Acer 720P brainwashed chromebook), I tried both full
>>>> speed and high speed. Still throttling but less bad.
>>>>
>>>> Then on desktop, with Edison kernel 5.12-rc5 as above + this patch:
>>>>
>>>> diff --git a/drivers/usb/dwc3/dwc3-pci.c b/drivers/usb/dwc3/dwc3-pci.c
>>>>
>>>> index 4c5c6972124a..a9268c085840 100644
>>>>
>>>> --- a/drivers/usb/dwc3/dwc3-pci.c
>>>>
>>>> +++ b/drivers/usb/dwc3/dwc3-pci.c
>>>>
>>>> @@ -122,6 +122,7 @@ static const struct property_entry
>>>> dwc3_pci_mrfld_properties[] = {
>>>>
>>>> PROPERTY_ENTRY_STRING("linux,extcon-name", "mrfld_bcove_pwrsrc"),
>>>>
>>>> PROPERTY_ENTRY_BOOL("snps,dis_u3_susphy_quirk"),
>>>>
>>>> PROPERTY_ENTRY_BOOL("snps,dis_u2_susphy_quirk"),
>>>>
>>>> + PROPERTY_ENTRY_BOOL("snps,dis_enblslpm_quirk"),
>>>>
>>>> PROPERTY_ENTRY_BOOL("linux,sysdev_is_parent"),
>>>>
>>>> {}
>>>>
>>>> };
>>>>
>>>> This fixes the throttling but reveals I had actually at least 2 bugs:
>>>>
>>>> 1) throttling due to LPM, this seems solved now, thanks to much!
>>> Now that we can confirm the speed throttling is related to LPM. We can
>>> try to experiment further. (IMO, LPM is an important feature and
>>> totally disabling LPM seems like using a sledgehammer to crack a nut)
>>>
>>> I suspect that your phy/HW has a higher low power exit latency. I don't
>>> think you provided any HIRD threshold property in your setup right? So
>>> by default, dwc3 sets the base line BESL value to 1 (or 150us). Unless
>>> you know what your phy/HW is capable of, try to test and increase the
>>> recommended BESL value. The range can be from 0 to 15 where 0 is 150us
>>> and 15 is 10ms. Maybe try 6 (i.e. 1ms).
>>>
>>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>>> index 60e850a395a2..423533df8927 100644
>>> --- a/drivers/usb/dwc3/gadget.c
>>> +++ b/drivers/usb/dwc3/gadget.c
>>> @@ -2895,7 +2895,7 @@ static void dwc3_gadget_config_params(struct 
>>> usb_gadget *g,
>>>                   * recommended BESL baseline to 1 and clamp the 
>>> BESL deep to be
>>>                   * within 2 to 15.
>>>                   */
>>> -               params->besl_baseline = 1;
>>> +               params->besl_baseline = 6;
>>>                  if (dwc->is_utmi_l1_suspend)
>>>                          params->besl_deep =
>>>                                  clamp_t(u8, dwc->hird_threshold, 2, 
>>> 15);
>>>
>> I will try and report back, hopefully this evening.
> I tried this and it seems to have the same effect as dis_enblslpm_quirk
>>>
>>>> 2) a problem with usb plug detection
>>>>
>>>> When I unplug/replug the gadget cable I need to do that at least 
>>>> another
>>>> time before gadget is detected. So unplug/replug/unplug/replug 
>>>> seems to
>>>> work.
>>>>
>>>> Also this platform has a HW switch to select host/device mode, with
>>>> separate connectors for host and device.
>>>>
>>>> When I flip the switch to host it immediately changes to host.
>>>>
>>>> Flipping to device leaves the LEDs on my connected usb hub on, so it's
>>>> still powered (but not operational).
>>>>
>>>> Flipping fast host/device (within 1/2 sec) hub LEDs turns off. But I
>>>> still need to additionally unplug/replug the gadget cable to get 
>>>> that to
>>>> work.
>>>>
>>> The connection issue can come from different things. Please narrow 
>>> it down
>>> and make sure that you don't use any defective cable or bad hub. 
>>> Even then,
>>> it's difficult to determine whose fault it is from just the dmesg 
>>> and driver
>>> logs alone without looking at the USB traffic at the packet level.
>>>
>>> Btw, is your setup DRD? If you're switching mode, then I know that 
>>> dwc3 right
>>> now doesn't implement mode switching correctly.
>> Yes, we use Extcon driver to support DRD.
>>> You can see the discussion we have here:
>>> https://lore.kernel.org/linux-usb/20210108015115.27920-1-john.stultz@linaro.org/T/#t 
>>>
>> I see, that might indeed be related. I will try the patches to see if 
>> that works and report back.
>
> I applied both patches:
>
> usb: dwc3: Trigger a GCTL soft reset when switching modes in DRD
>
> usb: dwc3: Fix DRD mode change sequence following programming guide
>
> It doesn't have an effect on the need to unplug/replug neither on the 
> problems switch from host/device mode.

When I test the correct kernel it does have an effect :-)

In most cases the need to unplug/replug is removed, but not always. In 
the cases when I need to retry the host journal shows "can't set config 
#1, error -110"

The switch from host->device and device->host mode seems to be resolved.

Strangely, iperf3 now reports 130 Mbits/sec (down from 200 Mbits/sec).

>
> But it doesn't hurt either.
>
>>> BR,
>>> Thinh

  reply	other threads:[~2021-04-10 14:08 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-30 12:37 USB network gadget / DWC3 issue Andy Shevchenko
2021-03-30 16:17 ` Felipe Balbi
2021-03-30 20:26   ` Ferry Toth
2021-03-30 21:57     ` Ferry Toth
2021-04-02 19:12       ` Ferry Toth
2021-04-02 20:16         ` Thinh Nguyen
2021-04-02 22:40           ` Ferry Toth
2021-04-03  2:02             ` Thinh Nguyen
2021-04-03 11:25               ` Ferry Toth
2021-04-03 21:15                 ` Ferry Toth
2021-04-05 20:59                   ` Ferry Toth
2021-04-07  0:10                     ` Thinh Nguyen
2021-04-07  0:24                       ` Thinh Nguyen
2021-04-07 13:34                         ` Andy Shevchenko
2021-04-07 16:08                           ` Ferry Toth
2021-04-08 20:17                           ` Ferry Toth
2021-04-08 21:12                             ` Thinh Nguyen
2021-04-08 21:37                               ` Thinh Nguyen
2021-04-09 13:26                               ` Ferry Toth
2021-04-10 13:29                                 ` Ferry Toth
2021-04-10 14:08                                   ` Ferry Toth [this message]
2021-04-11  0:04                                     ` Thinh Nguyen
2021-04-11 15:26                                       ` Ferry Toth
2021-04-13  2:17                                         ` Thinh Nguyen
2021-04-13  8:45                                           ` Ferry Toth
2021-04-13 21:06                                           ` Ferry Toth
2021-04-13 21:21                                             ` Thinh Nguyen

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