On 2021/4/16 23:20, Alan Stern wrote: > 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? > URL: https://patchwork.kernel.org/project/linux-usb/patch/1616666652-37920-1-git-send-email-liulongfang@xxxxxxxxxx/ Thanks Longfang. >> 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 > . >
