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Message-ID: <449417ca-aae1-4868-a96f-a99ac5d187d6@gmail.com>
Date: Mon, 4 Mar 2024 21:21:19 +0100
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Subject: Re: [REGRESSION] Missing bcm5974 touchpad on Macbooks
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To: Takashi Iwai <tiwai@suse.de>,
 Javier Carrasco <javier.carrasco@wolfvision.net>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>, linux-input@vger.kernel.org,
 linux-kernel@vger.kernel.org, regressions@lists.linux.dev,
 Henrik Rydberg <rydberg@euromail.se>, John Horan <knasher@gmail.com>
References: <87sf161jjc.wl-tiwai@suse.de>
 <6ef6c5bf-e6e5-4711-81c6-6ae41de2e61e@wolfvision.net>
 <874jdm17yt.wl-tiwai@suse.de>
From: Javier Carrasco <javier.carrasco.cruz@gmail.com>
In-Reply-To: <874jdm17yt.wl-tiwai@suse.de>
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On 04.03.24 13:45, Takashi Iwai wrote:
> On Mon, 04 Mar 2024 12:26:48 +0100,
> Javier Carrasco wrote:
>>
>> On 04.03.24 09:35, Takashi Iwai wrote:
>>> Hi,
>>>
>>> we've received a few regression reports for openSUSE Leap about the
>>> missing touchpad on Macbooks.  After debugging, this turned out to be
>>> the backport of the commit 2b9c3eb32a699acdd4784d6b93743271b4970899
>>>     Input: bcm5974 - check endpoint type before starting traffic
>>>
>>> And, the same regression was confirmed on the upstream 6.8-rc6
>>> kernel.
>>>
>>> Reverting the commit above fixes the problem, the touchpad reappears.
>>>
>>> The detailed hardware info is found at:
>>>   https://bugzilla.suse.com/show_bug.cgi?id=1220030
>>>
>>> Feel free to join the bugzilla above, or let me know if you need
>>> something for debugging, then I'll delegate on the bugzilla.
>>>
>>>
>>> thanks,
>>>
>>> Takashi
>>>
>>
>> Hi Takashi,
>>
>> The commit adds a check to ensure that the endpoint type is interrupt.
>>
>> According to that report, the issue arose with a MacBook Pro 5.1 (no
>> button, only trackpad endpoint), so the check on the tp_ep address
>> (0x81) returns false. I assume that you see an error message
>> ("Unexpected non-int endpoint) and  the probe function fails returning
>> -ENODEV.
> 
> Right, there is the message.
> 
>> Do you see any warning in the logs when you revert the commit? It was
>> added to prevent using wrong endpoint types, which will display the
>> following warning: "BOGUS urb xfer, pipe "some_number" != type
>> "another_number""
> 
> The revert was tested on the downstream kernel, but it has also the
> check of bogus pipe, and there was no such warning, as far as I see
> the report.
> 
>> I am just wondering if for some reason the check on interrupt type is
>> wrong here.
> 
> I'll ask reporters to give the lsusb -v output so that we can take a
> deeper look.  Also, I'm building a test kernel based on 6.8-rc7 with
> the revert, and ask reporters to test with it, just to be sure.
> 
> 
> thanks,
> 
> Takashi

I retrieved the relevant node from the report that was uploaded a few
minutes ago:

Bus 003 Device 003: ID 05ac:0237 Apple, Inc. Internal Keyboard/Trackpad
(ISO)
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0         8
  idVendor           0x05ac Apple, Inc.
  idProduct          0x0237 Internal Keyboard/Trackpad (ISO)
  bcdDevice            0.77
  iManufacturer           1 Apple, Inc.
  iProduct                2 Apple Internal Keyboard / Trackpad
  iSerial                 0
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength       0x0054
    bNumInterfaces          3
    bConfigurationValue     1
    iConfiguration          0
    bmAttributes         0xa0
      (Bus Powered)
      Remote Wakeup
    MaxPower               40mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         3 Human Interface Device
      bInterfaceSubClass      1 Boot Interface Subclass
      bInterfaceProtocol      1 Keyboard
      iInterface              3 Apple Internal Keyboard
        HID Device Descriptor:
          bLength                 9
          bDescriptorType        33
          bcdHID               1.11
          bCountryCode           13 International (ISO)
          bNumDescriptors         1
          bDescriptorType        34 Report
          wDescriptorLength     156
         Report Descriptors:
           ** UNAVAILABLE **
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x83  EP 3 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x000a  1x 10 bytes
        bInterval               8
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         3 Human Interface Device
      bInterfaceSubClass      0
      bInterfaceProtocol      0
      iInterface              4 Touchpad
        HID Device Descriptor:
          bLength                 9
          bDescriptorType        33
          bcdHID               1.11
          bCountryCode            0 Not supported
          bNumDescriptors         1
          bDescriptorType        34 Report
          wDescriptorLength      27
         Report Descriptors:
           ** UNAVAILABLE **
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               2
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         3 Human Interface Device
      bInterfaceSubClass      1 Boot Interface Subclass
      bInterfaceProtocol      2 Mouse
      iInterface              4 Touchpad
        HID Device Descriptor:
          bLength                 9
          bDescriptorType        33
          bcdHID               1.11
          bCountryCode            0 Not supported
          bNumDescriptors         1
          bDescriptorType        34 Report
          wDescriptorLength      52
         Report Descriptors:
           ** UNAVAILABLE **
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x84  EP 4 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0008  1x 8 bytes
        bInterval               8
Device Status:     0x0000
  (Bus Powered)


There is indeed an interrupt endpoint with address 0x81, but the driver
defines bInterfaceProtocol = 2 (Mouse), and the endpoint in that
interface is 0x84:

#define BCM5974_DEVICE(prod) {					\
	.match_flags = (USB_DEVICE_ID_MATCH_DEVICE |		\
			USB_DEVICE_ID_MATCH_INT_CLASS |		\
			USB_DEVICE_ID_MATCH_INT_PROTOCOL),	\
	.idVendor = USB_VENDOR_ID_APPLE,			\
	.idProduct = (prod),					\
	.bInterfaceClass = USB_INTERFACE_CLASS_HID,		\
	.bInterfaceProtocol = USB_INTERFACE_PROTOCOL_MOUSE	\
}

where USB_INTERFACE_PROTOCOL_MOUSE = 2.


My interpretation is that the driver is checking if the endpoint with
address 0x81 form the interface with bInterfaceProtocol = 2 (that is the
last interface of the list, the one with bInterfaceNumber = 2), but it
is not found, because its only endpoint has a different address (0x84).

Interestingly, 0x84 is the address given to the endpoint of the button
interface. The button interface should not be relevant for Macbook 5,1
(TYPE 2 in the driver), according to 43f482b48d03 ("Input: bcm5974 -
only setup button urb for TYPE1 devices").

If that is true, does anyone know why bInterfaceProtocol is always set
to USB_INTERFACE_PROTOCOL_MOUSE, and why the driver works anyway with
bEndpointAddress = 0x81 for the trackpad? The urb setup for 0x84 is only
executed for TYPE 1 devices, and the mouse interface does not have an
endpoint with address 0x81. Or am I missing something?

We could revert the patch in question, but I see no reason why checking
an expected interrupt endpoint should cause trouble. It looks like there
is something fishy going on.

Best regards,
Javier Carrasco