Re: Regression: onboard-usb-hub breaks USB on RPi 3

[Stefan Wahren <stefan.wahren@i2se.com>]

Hi Matthias,

Am 20.12.22 um 23:50 schrieb Matthias Kaehlcke:
>
> Today I learned that regulator_get() doesn't return an error when the regulator
> isn't specified, but the 'dummy regulator'. With that the platform driver is
> instantiated, which is not intended. The proper fix is probably to skip the
> creation of the 'raw' platform device in onboard_hub_create_pdevs() when the
> 'vdd-supply' does not exist.

Yes, i can confirm this by debugfs:

  regulator                      use open bypass  opmode voltage 
current     min     max
---------------------------------------------------------------------------------------
  regulator-dummy                  8    7      0 unknown 0mV     0mA     
0mV     0mV
     serial0-0-vddio 1                                 0mA     0mV     0mV
     serial0-0-vbat 1                                 0mA     0mV     0mV
     3f980000.usb:usb-port@1:usb-port@1-vdd 
1                                 0mA     0mV     0mV
     3f980000.usb:usb-port@1-vdd 1                                 
0mA     0mV     0mV
     3f980000.usb-vusb_a 1                                 0mA     
0mV     0mV
     3f980000.usb-vusb_d 1                                 0mA     
0mV     0mV
     phy-vcc 1                                 0mA     0mV     0mV

>
> I tried to repro the Rpi 3 case by adjusting sc7280-herobrine.dtsi to look
> somewhat similar to the Rpi 3 hub config, but so far I wasn't 'successful'
> with breaking USB by deleting 'vdd-supply' (and 'peer-hub'). So I don't fully
> understand your scenario, but I'm relatively confident that not creating the
> platform devices should fix it.

I just played a little bit with 
arch/arm/boot/dts/bcm283x-rpi-lan7515.dtsi and removed only the second 
hub node (including ethernet chip). After this the issue also doesn't 
occur without any modification to onboard-usb-hub. So it seems to me 
that the real issue is caused by the cascade of 2x Microchip USB2514B 
USB 2.0 hubs.

Here are the relevant kernel log entries:

[    4.025150] dwc2 3f980000.usb: supply vusb_d not found, using dummy 
regulator
[    4.038776] dwc2 3f980000.usb: supply vusb_a not found, using dummy 
regulator
[    4.104207] dwc2 3f980000.usb: DWC OTG Controller
[    4.115852] dwc2 3f980000.usb: new USB bus registered, assigned bus 
number 1
[    4.129921] dwc2 3f980000.usb: irq 66, io mem 0x3f980000
[    4.513217] usb 1-1: new high-speed USB device number 2 using dwc2
[    5.123296] usb 1-1.1: new high-speed USB device number 3 using dwc2
[    5.623217] usb 1-1.3: new low-speed USB device number 4 using dwc2
[    5.785049] input: HID 046a:0011 as 
/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.3/1-1.3:1.0/0003:046A:0011.0001/input/input0
[    5.863240] usb 1-1.1.2: new low-speed USB device number 5 using dwc2
[    5.868998] hid-generic 0003:046A:0011.0001: input: USB HID v1.11 
Keyboard [HID 046a:0011] on usb-3f980000.usb-1.3/input0
[    6.031327] input: PixArt Microsoft USB Optical Mouse as 
/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2:1.0/0003:045E:00CB.0002/input/input1
[    6.031490] hid-generic 0003:045E:00CB.0002: input: USB HID v1.11 
Mouse [PixArt Microsoft USB Optical Mouse] on usb-3f980000.usb-1.1.2/input0
[    6.333278] usb 1-1.1.1: new high-speed USB device number 6 using dwc2
[   24.165633] usbcore: registered new interface driver lan78xx
[   24.423801] onboard-usb-hub 3f980000.usb:usb-port@1: supply vdd not 
found, using dummy regulator
[   24.424202] usbcore: registered new device driver onboard-usb-hub
[   24.424376] usb 1-1.1: USB disconnect, device number 3
[   24.424385] usb 1-1.1.1: USB disconnect, device number 6
[   24.564921] usb 1-1.1.2: USB disconnect, device number 5
[   24.624696] usb 1-1.3: USB disconnect, device number 4
[   25.523236] usb 1-1.1: new high-speed USB device number 7 using dwc2
[   26.143248] usb 1-1.3: new low-speed USB device number 8 using dwc2
[   26.305673] input: HID 046a:0011 as 
/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.3/1-1.3:1.0/0003:046A:0011.0003/input/input2
[   26.374840] hid-generic 0003:046A:0011.0003: input: USB HID v1.11 
Keyboard [HID 046a:0011] on usb-3f980000.usb-1.3/input0
[   26.383241] usb 1-1.1.2: new low-speed USB device number 9 using dwc2
[   26.521526] input: PixArt Microsoft USB Optical Mouse as 
/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.2/1-1.1.2:1.0/0003:045E:00CB.0004/input/input3
[   26.522241] hid-generic 0003:045E:00CB.0004: input: USB HID v1.11 
Mouse [PixArt Microsoft USB Optical Mouse] on usb-3f980000.usb-1.1.2/input0
[   26.833251] usb 1-1.1.1: new high-speed USB device number 10 using dwc2

As you can see the input devices are deregistered after probing of 
onboard-usb-hub and then registered again. The re-registering doesn't 
happen in the error case (as in my first email). Also in error case i 
noticed an unusual high load on the Rpi board, which doesn't occur in 
good case. Is it possible that both onboard-usb-hub instances are in 
some kind of deadlock?

>
> I'll try to send out a v2 of the fix before disappearing over the holidays
> after tomorrow.