[BISSECTED]: BUG: usb: dwc3: usb ports not working anymore on odroid-XU4

[Richard Genoud]

Hi,
Since commit c499ff71ff2a2 ("usb: dwc3: core: re-factor init and exit paths")
(merged in 4.8), the usb ports on odroid-XU4 don't work anymore.

[ Actually, it's commit 2164a476205ccc ("usb: dwc3: set SUSPHY bit for all cores"), cf below ]

Inserting an usb key (USB2.0) on the USB3.0 port result in:
[   64.488264] xhci-hcd xhci-hcd.2.auto: Port resume took longer than 20000 msec, port status = 0xc400fe3
[   74.568156] xhci-hcd xhci-hcd.2.auto: xHCI host not responding to stop endpoint command.
[   74.574806] xhci-hcd xhci-hcd.2.auto: Assuming host is dying, halting host.
[   74.601970] xhci-hcd xhci-hcd.2.auto: HC died; cleaning up
[   74.606276] usb 3-1: USB disconnect, device number 2
[   74.613565] usb 4-1: USB disconnect, device number 2
[   74.621208] usb usb3-port1: couldn't allocate usb_device
NB: it's not related to USB2.0 devices, I get the same result with an USB3.0 device (SATA to USB3 for instance).
NB2: it doesn't happen on an odriod-XU3 board, that doesn't have the realtek RTL8153 chip.

I instrumented what was read/written in the registers before and after this patch, and I found that the culprit is:
	if (dwc->revision > DWC3_REVISION_194A)
		reg |= DWC3_GUSB3PIPECTL_SUSPHY;
Before commit c499ff71ff2a2 ("usb: dwc3: core: re-factor init and exit paths"), dwc3_phy_setup() was
done early in dwc3_probe() and thus, dwc->revision wasn't set yet (==0)
After this commit, dwc3_phy_setup() is done in dwc3_core_init(), after setting dwc->revision (it's done in dwc3_core_is_valid()).

(The dwc3->revision on odroid-XU4 is 5533200a.)

If I comment out the 2 lines:
	if (dwc->revision > DWC3_REVISION_194A)
		reg |= DWC3_GUSB3PIPECTL_SUSPHY;
The usb key is recognized right away:
[   38.008158] usb 3-1.2: new high-speed USB device number 3 using xhci-hcd
[   38.138924] usb 3-1.2: New USB device found, idVendor=abcd, idProduct=1234
[   38.144399] usb 3-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3

I took a look at the history behind those 2 lines, and they've been introduced by:
commit 2164a476205ccc ("usb: dwc3: set SUSPHY bit for all cores") in 3.19.
In 3.19, the dwc->revision dwc3_phy_setup() was set in dwc3_core_init().
And, booting a 3.19 kernel on XU4 gives the same error (whereas booting a 3.18 kernel is ok)

[ So, I should have started this email with:
Since commit 2164a476205ccc ("usb: dwc3: set SUSPHY bit for all cores"),
the usb ports on odroid-XU4 don't work anymore. ]

The funny thing is that commit 45bb7de213d8("usb: dwc3: setup phys earlier") (merged in 4.2)
moved dwc3_phy_setup() in dwc3_probe(), way before dwc->revision was set, acting like a revert
on commit 2164a476205c("usb: dwc3: set SUSPHY bit for all cores")
That's why on 4.2, inserting an USB key on odroid-XU4 worked again,

So, to make a resume:
xxx-> 3.18: usb ok
3.19->4.1: usb error (due to commit 2164a476205ccc ("usb: dwc3: set SUSPHY bit for all cores"))
4.2->4.7: usb ok (due to commit 45bb7de213d8("usb: dwc3: setup phys earlier"))
4.8->now: usb error (due to commit c499ff71ff2a2 ("usb: dwc3: core: re-factor init and exit paths"))


any idea on this ?

regards,
Richard