linux-kernel - Re: [PATCH] xhci: Make debug message consistent with bus and port number

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Message-Id: <2542B92A-9E0B-4907-BF29-EA244597CC7B@canonical.com>
Date:   Tue, 30 Jun 2020 19:46:45 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Mathias Nyman <mathias.nyman@...ux.intel.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mathias Nyman <mathias.nyman@...el.com>,
        "open list:USB XHCI DRIVER" <linux-usb@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] xhci: Make debug message consistent with bus and port
 number



> On Jun 8, 2020, at 17:29, Mathias Nyman <mathias.nyman@...ux.intel.com> wrote:
> 
> On 8.6.2020 6.57, Kai-Heng Feng wrote:
>> 
>> 
>>> On May 7, 2020, at 18:35, Mathias Nyman <mathias.nyman@...ux.intel.com> wrote:
>>> 
>>> On 7.5.2020 11.21, Greg Kroah-Hartman wrote:
>>>> On Thu, May 07, 2020 at 03:58:36PM +0800, Kai-Heng Feng wrote:
>>>>> 
>>>>> 
>>>>>> On May 7, 2020, at 15:31, Greg Kroah-Hartman <gregkh@...uxfoundation.org> wrote:
>>>>>> 
>>>>>> On Thu, May 07, 2020 at 03:15:01PM +0800, Kai-Heng Feng wrote:
>>>>>>> 
>>>>>>> 
>>>>>>>> On May 7, 2020, at 14:45, Greg Kroah-Hartman <gregkh@...uxfoundation.org> wrote:
>>>>>>>> 
>>>>>>>> On Thu, May 07, 2020 at 02:17:55PM +0800, Kai-Heng Feng wrote:
>>>>>>>>> Current xhci debug message doesn't always output bus number, so it's
>>>>>>>>> hard to figure out it's from USB2 or USB3 root hub.
>>>>>>>>> 
>>>>>>>>> In addition to that, some port numbers are offset to 0 and others are
>>>>>>>>> offset to 1. Use the latter to match the USB core.
>>>>>>>>> 
>>>>>>>>> So use "bus number - port index + 1" to make debug message consistent.
>>>>>>>>> 
>>>>>>>>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
>>>>>>>>> ---
>>>>>>>>> drivers/usb/host/xhci-hub.c | 41 +++++++++++++++++++++----------------
>>>>>>>>> 1 file changed, 23 insertions(+), 18 deletions(-)
>>>>>>>>> 
>>>>>>>>> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
>>>>>>>>> index f37316d2c8fa..83088c262cc4 100644
>>>>>>>>> --- a/drivers/usb/host/xhci-hub.c
>>>>>>>>> +++ b/drivers/usb/host/xhci-hub.c
>>>>>>>>> @@ -1241,7 +1241,8 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
>>>>>>>>> 			temp = readl(ports[wIndex]->addr);
>>>>>>>>> 			/* Disable port */
>>>>>>>>> 			if (link_state == USB_SS_PORT_LS_SS_DISABLED) {
>>>>>>>>> -				xhci_dbg(xhci, "Disable port %d\n", wIndex);
>>>>>>>>> +				xhci_dbg(xhci, "Disable port %d-%d\n",
>>>>>>>>> +					 hcd->self.busnum, wIndex + 1);
>>>>>>>> 
>>>>>>>> Shouldn't xhci_dbg() show the bus number already?  
>>>>>>> 
>>>>>>> It's the PCI bus number, different to USB2/USB3 root hub bus number...
>>>>>> 
>>>>>> But if this is using dev_dbg(), and it is, then you know how to look
>>>>>> that up by seeing where that device is in sysfs at that point in time.
>>>>>> 
>>>>>> So why add this again?
>>>>> 
>>>>> xHCI has two HCD, one for USB2 and one for USB3.
>>>>> If both of their port with same number are in use, for instance, port 1, then they are port 1-1 and port 2-1.
>>>>> Right now the debug message only show "Port 1", we still can't find the corresponding port via sysfs with insufficient info.
>>>> 
>>>> Look at the full kernel log line, the xhci hcd device should be showing
>>>> you unique information.  If not, something else is wrong.
>>>> 
>>> 
>>> What Kai-Heng suggest here makes sense, and is useful.
>>> We use similar style debugging in other places, and it is helpful as it matches
>>> usb core debugging style.
>>> 
>>> This might seem odd but reason is that the xHC controller is one device which
>>> doesn't really separate USB2 and USB3.
>>> All ports are for example in one long array.
>>> 
>>> On the xhci driver side things look very different. We register two HCD's,
>>> one for usb 2 and one for USB 3. In many cases the debugging is not tied to a HCD
>>> in any way,  (starting, stopping controller, command completion interrupts etc),
>>> other cases the debugging is very much tied to a specific hcd,
>>> for example when we are handling a port requsts for the roothub.
>> 
>> A gentle ping...
>> 
> 
> Added to my for-usb-next branch, (which I'll need to rebase on 5.8-rc1 once released)

Hmm, not seeing this patch from mainline, next or xhci tree..

Kai-Heng
> 
> -Mathias
>