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Commit e36f88c4 authored by Roy Luo's avatar Roy Luo
Browse files

Support identifying usb midi device using usb sysfs 

Out-of-tree ACK patches previously enabled MIDI device identification
via the "/sys/class/android_usb/android0/f_midi/alsa" sysfs node.
This change introduces a new, upstream-compliant method for MIDI
device identification. This method requires the upstream patch [1]
within the underlying ACK.

[1] https://patchwork.kernel.org/project/linux-usb/patch/20240307030922.3573161-1-royluo@google.com/

Flag: android.hardware.usb.flags.enable_usb_sysfs_midi_identification
Bug: 333778731
Test: exercise usb midi with the flag on/off
Change-Id: I64635f083541bfc59bfa4857d0fc5f20a5f3c2f5
parent 2246bcc5

core/java/android/hardware/usb/flags/system_sw_usb_flags.aconfig

+8 −1
Original line number Diff line number Diff line
@@ -29,3 +29,10 @@ flag { 
    description: "Enables signal API with staking"

    bug: "287498482"

}



flag {

    name: "enable_usb_sysfs_midi_identification"

    namespace: "system_sw_usb"

    description: "Enable identifying midi device using USB sysfs"

    bug: "333778731"

}

services/usb/java/com/android/server/usb/UsbDeviceManager.java

+64 −11
Original line number Diff line number Diff line
@@ -80,6 +80,7 @@ import android.service.usb.UsbDeviceManagerProto; 
import android.service.usb.UsbHandlerProto;

import android.util.Pair;

import android.util.Slog;

import android.text.TextUtils;



import com.android.internal.annotations.GuardedBy;

import com.android.internal.logging.MetricsLogger;
@@ -110,6 +111,8 @@ import java.util.NoSuchElementException; 
import java.util.Scanner;

import java.util.Set;

import java.util.concurrent.atomic.AtomicInteger;

import java.util.regex.Matcher;

import java.util.regex.Pattern;



/**

 * UsbDeviceManager manages USB state in device mode.
@@ -135,6 +138,11 @@ public class UsbDeviceManager implements ActivityTaskManagerInternal.ScreenObser 
     */

    private static final String NORMAL_BOOT = "normal";



    /**

     *  UDC controller for the ConfigFS USB Gadgets.

     */

    private static final String USB_CONTROLLER_NAME_PROPERTY = "sys.usb.controller";



    private static final String USB_STATE_MATCH =

            "DEVPATH=/devices/virtual/android_usb/android0";

    private static final String ACCESSORY_START_MATCH =
@@ -932,6 +940,42 @@ public class UsbDeviceManager implements ActivityTaskManagerInternal.ScreenObser 
            sEventLogger.enqueue(new EventLogger.StringEvent("USB intent: " + intent));

        }



        private void getMidiCardDevice() throws FileNotFoundException {

            String controllerName =  getSystemProperty(USB_CONTROLLER_NAME_PROPERTY, "");

            if (TextUtils.isEmpty(controllerName)) {

                throw new FileNotFoundException("controller name not found");

            }



            File soundDir = new File("/sys/class/udc/" + controllerName + "/gadget/sound");

            if (!soundDir.exists()) {

                throw new FileNotFoundException("sound device not found");

            }



            // There should be exactly one sound card

            File[] cardDirs = FileUtils.listFilesOrEmpty(soundDir,

                                                         (dir, file) -> file.startsWith("card"));

            if (cardDirs.length != 1) {

                throw new FileNotFoundException("sound card not match");

            }



            // There should be exactly one midi device

            File[] midis = FileUtils.listFilesOrEmpty(cardDirs[0],

                                                      (dir, file) -> file.startsWith("midi"));

            if (midis.length != 1) {

                throw new FileNotFoundException("MIDI device not match");

            }



            Pattern pattern = Pattern.compile("midiC(\\d+)D(\\d+)");

            Matcher matcher = pattern.matcher(midis[0].getName());

            if (matcher.matches()) {

                mMidiCard = Integer.parseInt(matcher.group(1));

                mMidiDevice = Integer.parseInt(matcher.group(2));

                Slog.i(TAG, "Found MIDI card " + mMidiCard + " device " + mMidiDevice);

            } else {

                throw new FileNotFoundException("MIDI name not match");

            }

        }



        private void updateUsbFunctions() {

            updateMidiFunction();

            updateMtpFunction();
@@ -941,6 +985,14 @@ public class UsbDeviceManager implements ActivityTaskManagerInternal.ScreenObser 
            boolean enabled = (mCurrentFunctions & UsbManager.FUNCTION_MIDI) != 0;

            if (enabled != mMidiEnabled) {

                if (enabled) {

                    if (android.hardware.usb.flags.Flags.enableUsbSysfsMidiIdentification()) {

                        try {

                            getMidiCardDevice();

                        } catch (FileNotFoundException e) {

                            Slog.e(TAG, "could not identify MIDI device", e);

                            enabled = false;

                        }

                    } else {

                        Scanner scanner = null;

                        try {

                            scanner = new Scanner(new File(MIDI_ALSA_PATH));
@@ -955,6 +1007,7 @@ public class UsbDeviceManager implements ActivityTaskManagerInternal.ScreenObser 
                            }

                        }

                    }

                }

                mMidiEnabled = enabled;

            }

            mUsbAlsaManager.setPeripheralMidiState(