From:   Stefan Wahren <stefan.wahren@i2se.com>
Subject: mt76x0: probing issues on Raspberry Pi
To:     Felix Fietkau <nbd@nbd.name>,
        Lorenzo Bianconi <lorenzo.bianconi@redhat.com>,
        Stanislaw Gruszka <sgruszka@redhat.com>
Cc:     linux-wireless@vger.kernel.org, linux-usb@vger.kernel.org
Message-ID: <ee482b50-e20f-df8c-3e87-4f7796210f73@i2se.com>
Date:   Tue, 29 Jan 2019 10:12:23 +0100
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Hi,

recently i discovered a bug report about probing issues of the mt76x0
driver using T2U Archer on the Raspberry Pi 3 B (Linux 4.19.14, Aarch64)
[1].

Also i tried a T2UH Archer on my Raspberry Pi 3 B+ with a recent
Linux-Next and i'm getting the following output:

Vendor request req:07 off:0404 failed:-110
...

instead of successful probe. The author of the former bug report
provided the "lsusb -v" on a working system:

Bus 001 Device 009: ID 148f:761a Ralink Technology, Corp. MT7610U
("Archer T2U" 2.4G+5G WLAN Adapter
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.01
  bDeviceClass            0
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0        64
  idVendor           0x148f Ralink Technology, Corp.
  idProduct          0x761a MT7610U ("Archer T2U" 2.4G+5G WLAN Adapter
  bcdDevice            1.00
  iManufacturer           1 MediaTek
  iProduct                2 WiFi
  iSerial                 3 1.0
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength       0x004a
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0
    bmAttributes         0xa0
      (Bus Powered)
      Remote Wakeup
    MaxPower              160mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           8
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      2
      bInterfaceProtocol    255
      iInterface              0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x84  EP 4 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               1
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x85  EP 5 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               1
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x08  EP 8 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               1
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x04  EP 4 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               1
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x05  EP 5 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               1
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x06  EP 6 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               1
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x07  EP 7 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               1
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x09  EP 9 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               1
Binary Object Store Descriptor:
  bLength                 5
  bDescriptorType        15
  wTotalLength       0x000c
  bNumDeviceCaps          1
  USB 2.0 Extension Device Capability:
    bLength                 7
    bDescriptorType        16
    bDevCapabilityType      2
    bmAttributes   0x00000002
      HIRD Link Power Management (LPM) Supported
can't get debug descriptor: Resource temporarily unavailable
Device Status:     0x0000
  (Bus Powered)

The BCM2835 on the Raspberry Pi only have 8 EP. So i suspect that the
amount of EP is the problem here.

Is it possible to reduce them in the mt76x0 driver?

[1] - https://github.com/raspberrypi/linux/issues/2817