Problem with midi keyboard via USB #102

fabbrimichele · 2021-03-21T15:10:27Z

fabbrimichele
Mar 21, 2021

Hello and thanks for the wonderful project.

I am having an issue when I try to use my midi keyboard (Prodipe 49N) connected via USB to a raspberry PI3.
The keyboard works fine with ubuntu/linux without any specific driver.

I already tried to add usbpowerdelay=2000 to the cmdline.txt file without success.
I also tried to connect the USB cable before powering on the keyboard and after into all the sockets.

I tried a kernel provided in another answer with HDMI enabled and I get the error message:
dwhci: Transaction failed (status 0xA)

The keyboard when connected to linux machine reports the following.

With dmesg:

[23838.644233] usb 1-1: new low-speed USB device number 5 using xhci_hcd
[23838.830876] usb 1-1: config 1 interface 1 altsetting 0 endpoint 0x81 is Bulk; changing to Interrupt
[23838.830885] usb 1-1: config 1 interface 1 altsetting 0 endpoint 0x1 is Bulk; changing to Interrupt
[23838.847434] usb 1-1: New USB device found, idVendor=1acc, idProduct=0601
[23838.847442] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[23838.847448] usb 1-1: Product: Ta Horng MIDI I/O
[23838.847453] usb 1-1: Manufacturer: Ta Horng Musical Instrument
[23838.937860] usbcore: registered new interface driver snd-usb-audio

With lsusb

Bus 001 Device 005: ID 1acc:0601 Midiplus Co, Ltd.

With aconnect -i

client 0: 'System' [type=kernel]
    0 'Timer           '
    1 'Announce        '
client 14: 'Midi Through' [type=kernel]
    0 'Midi Through Port-0'
client 20: 'Ta Horng MIDI I/O' [type=kernel,card=1]
    0 'Ta Horng MIDI I/O MIDI 1'

Is there anything I can try to fix it?

dwhinham · 2021-03-21T15:24:47Z

dwhinham
Mar 21, 2021
Maintainer

Hi there - thanks for the info!

Could you try lsusb again but with -vvv aswell - this will provide more information, though you'll probably have to scroll acround and find the parts relevant to the keyboard.

The HDMI build you tried was likely quite old and there have been some changes to USB code since then.
Could you please try this build? https://github.com/dwhinham/mt32-pi/actions/runs/671793349

This is v0.9.1 - there is a kernels-hdmi archive there with kernels that should display the logs.

If you could post a screenshot of as much of the log as you can that would be helpful.

Thanks!

4 replies

fabbrimichele Mar 21, 2021
Author

Hi and thanks for the quick reply!

I attached two screen shots of the kernel log:

the first one shows the log before connecting the keyboard
the second one shows the log connecting and immediately disconnecting the keyboard (the error transaction failed is shown when the keyboard is attached).

The following is the output of lsusb -vvv on a ubuntu machine:

Bus 001 Device 006: ID 1acc:0601 Midiplus Co, Ltd. 
Couldn't open device, some information will be missing
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0         8
  idVendor           0x1acc Midiplus Co, Ltd.
  idProduct          0x0601 
  bcdDevice            1.04
  iManufacturer           1 
  iProduct                2 
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength          101
    bNumInterfaces          2
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              300mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           0
      bInterfaceClass         1 Audio
      bInterfaceSubClass      1 Control Device
      bInterfaceProtocol      0 
      iInterface              0 
      AudioControl Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      1 (HEADER)
        bcdADC               1.00
        wTotalLength            9
        bInCollection           1
        baInterfaceNr( 0)       1
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass         1 Audio
      bInterfaceSubClass      3 MIDI Streaming
      bInterfaceProtocol      0 
      iInterface              0 
      MIDIStreaming Interface Descriptor:
        bLength                 7
        bDescriptorType        36
        bDescriptorSubtype      1 (HEADER)
        bcdADC               1.00
        wTotalLength           65
      MIDIStreaming Interface Descriptor:
        bLength                 6
        bDescriptorType        36
        bDescriptorSubtype      2 (MIDI_IN_JACK)
        bJackType               1 Embedded
        bJackID                 1
        iJack                   0 
      MIDIStreaming Interface Descriptor:
        bLength                 6
        bDescriptorType        36
        bDescriptorSubtype      2 (MIDI_IN_JACK)
        bJackType               2 External
        bJackID                 2
        iJack                   0 
      MIDIStreaming Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      3 (MIDI_OUT_JACK)
        bJackType               1 Embedded
        bJackID                 3
        bNrInputPins            1
        baSourceID( 0)          2
        BaSourcePin( 0)         1
        iJack                   0 
      MIDIStreaming Interface Descriptor:
        bLength                 9
        bDescriptorType        36
        bDescriptorSubtype      3 (MIDI_OUT_JACK)
        bJackType               2 External
        bJackID                 4
        bNrInputPins            1
        baSourceID( 0)          1
        BaSourcePin( 0)         1
        iJack                   0 
      Endpoint Descriptor:
        bLength                 9
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0004  1x 4 bytes
        bInterval               0
        bRefresh                0
        bSynchAddress           0
        MIDIStreaming Endpoint Descriptor:
          bLength                 5
          bDescriptorType        37
          bDescriptorSubtype      1 (GENERAL)
          bNumEmbMIDIJack         1
          baAssocJackID( 0)       3
      Endpoint Descriptor:
        bLength                 9
        bDescriptorType         5
        bEndpointAddress     0x01  EP 1 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0004  1x 4 bytes
        bInterval               0
        bRefresh                0
        bSynchAddress           0
        MIDIStreaming Endpoint Descriptor:
          bLength                 5
          bDescriptorType        37
          bDescriptorSubtype      1 (GENERAL)
          bNumEmbMIDIJack         1
          baAssocJackID( 0)       1

dwhinham Mar 21, 2021
Maintainer

Thanks for the extra information.

As one last test - does the keyboard work on the Pi with Raspberry Pi OS or another Pi Linux distribution?

The device does appear to be a class-compliant MIDI interface and in theory should work - the USB MIDI driver attempts to configure it, but for some reason the data transfer between them is failing.

The USB drivers are part of the Circle baremetal framework that mt32-pi is built on.

Unfortunately it is difficult to fix this kind of thing because the USB controller driver for the Pi 0-3 is not 100% perfect - the USB controller used by the Pi has no public documentation. This means that what does work is a result of reverse-engineering and trying to port the Linux driver, which is very difficult. Rene Stange has done an amazing job trying to get as many USB devices working as possible with Circle, but some devices have strange behaviour which is difficult to cater for.

I'm tagging @rsta2 here in case he has any comments - it may be possible to investigate further with a special test kernel that can trace what's happening, otherwise we may just have to add this device to the "incompatible" list.

I noticed your keyboard has a MIDI OUT port, so you could work around the USB issue if you had a known-good USB MIDI interface (e.g. UM-ONE) to connect to it, or you could consider building/buying one of the GPIO MIDI interfaces in the wiki. Not ideal, but it would get it working.

Also, it might be worth trying the keyboard with a Pi 4 if you have access to one. The Pi 4 has a completely different USB controller and may work with your keyboard.

Thanks!

fabbrimichele Mar 21, 2021
Author

Thanks for taking time to explaining the issue.

I tested the keyboard with the Raspberry Pi OS and it works fine (I was able to connect it to fluidsynth with aconnect).
Attached are 2 screen shots of dmesg and aconnect.

I am not sure if it is worth to invest time for a keyboard that is not probably very popular, but I would be glad to do additional checks if there is anything else I can try.

I am not an expert but since the keyboard has 2 clients: Midi through and Midi I/O, I was wondering how the software knows which client to use?

rsta2 Mar 22, 2021

Hi there,

thanks for the logs. I can see three things from the logs:

The "Transaction failed (status 0xA)" message means, that an USB endpoint has STALLed. This is most likely the bulk-in endpoint, which is polled for input MIDI messages. A STALL from an USB device endpoint happens normally after an invalid request from the host.
How it seems, this keyboard is not fully USB 2.0 compliant. The wMaxPacketSize parameter is 4 bytes for both bulk endpoints (in and out). The USB 2.0 specification allows only values of 8, 16, 32, or 64 bytes here for full-speed endpoints and 512 bytes for high-speed endpoints.
Please note this comment and code from the Linux USB core, which generates the message "changing to Interrupt" in the dmesg log. How it seems, this is a low-speed USB device with a bulk endpoint, which is not allowed by the USB specification. Linux has a workaround to get it working, Circle has currently not.

I have to think about, if such a workaround can and should be implemented in Circle, which takes some time. I will come back on this.

rsta2 · 2021-03-22T10:38:57Z

rsta2
Mar 22, 2021

@dwhinham Hi Dale, if you want to try it, here is a patch for Circle, which tries to implement the workaround, mentioned in my previous comment:

diff --git a/lib/usb/usbendpoint.cpp b/lib/usb/usbendpoint.cpp
index 05a8127..dcadcc8 100644
--- a/lib/usb/usbendpoint.cpp
+++ b/lib/usb/usbendpoint.cpp
@@ -113,6 +113,25 @@ CUSBEndpoint::CUSBEndpoint (CUSBDevice *pDevice, const TUSBEndpointDescriptor *p
 	}
 #endif
 
+	// workaround for low-speed devices with bulk endpoints,
+	// which is normally forbidden by the USB spec.
+	if (   m_pDevice->GetSpeed () == USBSpeedLow
+	    && m_Type == EndpointTypeBulk)
+	{
+		m_Type = EndpointTypeInterrupt;
+
+		if (m_nMaxPacketSize > 8)
+		{
+			m_nMaxPacketSize = 8;
+		}
+
+#ifdef USE_USB_SOF_INTR
+		m_nInterval = 1;
+#else
+		m_nInterval = 20;
+#endif
+	}
+
 #if RASPPI >= 4
 	m_pXHCIEndpoint = new CXHCIEndpoint ((CXHCIUSBDevice *) m_pDevice, pDesc,
 					     (CXHCIDevice *) m_pDevice->GetHost ());

It would be good, if you could build a test kernel from your project, including this patch, so that @fabbrimichele can test it with his keyboard. Thanks!

21 replies

rsta2 Mar 24, 2021

Thanks Dale, let's see, if this build is running successfully for @fabbrimichele.

fabbrimichele Mar 24, 2021
Author

Thanks for the kernels!
I tested the kernel and it works beautifully.

I made two screen shoots: the first one is taken starting the raspberry with the keyboard attached, the second one is taken attaching the keyboard after the raspberry was already started.

dwhinham Mar 24, 2021
Maintainer

Thanks for testing - the logs look perfect!

We can now see the new log entries for "not fully USB compliant" which shows us Rene's workaround is in effect, and Plug & Play seems to be working too in your second screenshot.

I look forward to including this in the next release, perhaps it will also help gets some other unusual hardware working.

Many thanks to you both! 🙂🍻

rsta2 Mar 24, 2021

I'm glad, that is works. I have committed the patches to the develop branch in the Circle repo. Thank you both!

fabbrimichele Mar 24, 2021
Author

Thank you guys for the great projects :)

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Problem with midi keyboard via USB #102

fabbrimichele Mar 21, 2021

Replies: 2 comments · 25 replies

dwhinham Mar 21, 2021 Maintainer

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fabbrimichele Mar 21, 2021 Author

rsta2 Mar 22, 2021

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rsta2 Mar 24, 2021

fabbrimichele Mar 24, 2021 Author

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rsta2 Mar 24, 2021

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fabbrimichele
Mar 21, 2021

Replies: 2 comments 25 replies

dwhinham
Mar 21, 2021
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fabbrimichele Mar 21, 2021
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rsta2
Mar 22, 2021

fabbrimichele Mar 24, 2021
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