Messages in this thread | | | Date | Wed, 3 Nov 2021 04:29:01 +0800 | Subject | Re: [PATCH v2] usb: core: reduce power-on-good delay time of root hub | From | "Walt Jr. Brake" <> |
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On 2/11/2021 17:05, Mathias Nyman wrote: > On 1.11.2021 16.06, Alan Stern wrote: >> On Sat, Oct 30, 2021 at 12:49:37PM +0800, Walt Jr. Brake wrote: >>> This patch make USB 3.1 device cannot be detected, and I report the bug [1] >>> to archlinux three month ago. Yesterday I try to fix it myself, and after I >>> revert this patch, compile the kernel and test, it works. >>> >>> [1] https://bugs.archlinux.org/task/71660?project=1&pagenum=2 >>> >>> >>> diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h >>> index 22ea1f4f2d66..73f4482d833a 100644 >>> --- a/drivers/usb/core/hub.h >>> +++ b/drivers/usb/core/hub.h >>> @@ -148,10 +148,8 @@ static inline unsigned hub_power_on_good_delay(struct >>> usb_hub *hub) >>> { >>> unsigned delay = hub->descriptor->bPwrOn2PwrGood * 2; >>> >>> - if (!hub->hdev->parent) /* root hub */ >>> - return delay; >>> - else /* Wait at least 100 msec for power to become stable */ >>> - return max(delay, 100U); >>> + /* Wait at least 100 msec for power to become stable */ >>> + return max(delay, 100U); >>> } >> Mathias: >> >> It looks like the bPwrOn2PwrGood value in xhci-hcd's hub descriptor is >> too small for some USB 3.1 devices. >> >> Can you look into this? >> >> Alan Stern >> > At first glance the xhci roothub bPwrOn2PwrGood value looks ok. > xhci spec 5.4.8 states software should wait 20ms after asserting PP, before > attempting to change the state of the port. > > xhci driver sets desc->bPwrOn2PwrGood = 10; (2ms interval, so equals 20ms ) > > We should probably get this working immediately, so maybe revert that patch > while looking into the rootcause. > > Walt Jr. Brake, instead of reverting that patch, could you test if changing the > xhci roothub bPwrOn2PwrGood value helps. > > diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c > index a3f875eea751..756231a55602 100644 > --- a/drivers/usb/host/xhci-hub.c > +++ b/drivers/usb/host/xhci-hub.c > @@ -257,7 +257,7 @@ static void xhci_common_hub_descriptor(struct xhci_hcd *xhci, > { > u16 temp; > > - desc->bPwrOn2PwrGood = 10; /* xhci section 5.4.9 says 20ms max */ > + desc->bPwrOn2PwrGood = 50; /* The 20ms in xhci 5.4.8 isn't enough for USB 3.1 */ > desc->bHubContrCurrent = 0; > > desc->bNbrPorts = ports; > > Thanks > -Mathias
Mathias:
Sorry to reply lately. I test with your patch, it works.
I also test with setting bPwrOn2PwrGood to 45, and it not work.
Seems that the minimal value should be 50 for this case.
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