lkml.org 
[lkml]   [2021]   [Apr]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [RFC PATCH] USB:XHCI:skip hub registration
    From
    Date
    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@huawei.com>
    >>>
    >>> 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@huawei.com/
    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
    > .
    >

    \
     
     \ /
      Last update: 2021-04-17 05:11    [W:3.744 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site