On Fri, Apr 16, 2021 at 10:03:21AM +0800, liulongfang wrote: > On 2021/4/15 22:43, Alan Stern wrote: > > On Thu, Apr 15, 2021 at 08:22:38PM +0800, Longfang Liu wrote: > >> When the number of ports on the USB hub is 0, skip the registration > >> operation of the USB hub. > >> > >> The current Kunpeng930's XHCI hardware controller is defective. The number > >> of ports on its USB3.0 bus controller is 0, and the number of ports on > >> the USB2.0 bus controller is 1. > >> > >> In order to solve this problem that the USB3.0 controller does not have > >> a port which causes the registration of the hub to fail, this patch passes > >> the defect information by adding flags in the quirks of xhci and usb_hcd, > >> and finally skips the registration process of the hub directly according > >> to the results of these flags when the hub is initialized. > >> > >> Signed-off-by: Longfang Liu <liulongfang@xxxxxxxxxx> > > > > The objections that Greg raised are all good ones. > > > > But even aside from them, this patch doesn't actually do what the > > description says. The patch doesn't remove the call to usb_add_hcd > > for the USB-3 bus. If you simply skipped that call (and the > > corresponding call to usb_remove_hcd) when there are no > > ports on the root hub, none of the stuff in this patch would be needed. > > > > Alan Stern > > > > "[RFC PATCH] USB:XHCI:Adjust the log level of hub" I don't understand. What patch is that? Do you have a URL for it? > The current method is an improved method of the above patch. > This patch just make it skip registering USB-3 root hub if that hub has no ports, No, that isn't what this patch does. If the root hub wasn't registered, hub_probe wouldn't get called. But with your patch, the system tries to register the root hub, and it does call hub_probe, and then that function fails with a warning message. The way to _really_ akip registering the root hub is to change the xhci-hcd code. Make it skip calling usb_add_hcd. > after skipping registering, no port will not report error log,the goal of this > patch is reached without error log output. Why do you want to get rid of the error log output? There really _is_ an error, because the USB-3 hardware on your controller is defective. Since the hardware is buggy, we _should_ print an error message in the kernel log. Alan Stern
