Add a "usbinit" boot option to handle various buggy USB devices.

This replaces the "keyboard=buggy-usb" option, and adds a second
workaround to handle the problem seen in issue #107.

README.md

@@ -132,7 +132,13 @@ recognised:
     * where *type* is one of
       * legacy
       * usb
-      * buggy-usb
+  * usbdebug
+    * pauses after probing for USB keyboards
+  * usbinit=*mode*
+    * where *mode* is one of
+      * 1 = use the two-step init sequence for high speed devices
+      * 2 = add a second USB reset in the init sequence
+      * 3 = the combination of modes 1 and 2
   * console=ttyS*x*,*y*
     * activate serial/tty console output, where *x* is one of the following IO port
       *  0 = 0x3F8
@@ -152,9 +158,7 @@ recognised:
 Memtest86+ supports both the legacy keyboard interface (using I/O ports 0x60
 and 0x64) and USB keyboards (using its own USB device drivers). One or the
 other can be selected via the boot command line, If neither is selected, the
-default is to use both. An additional option on the boot command line is
-`buggy-usb` which enables the longer initialisation sequence required by some
-older USB devices.
+default is to use both.
 
 Older BIOSs usually support USB legacy keyboard emulation, which makes USB
 keyboards act like legacy keyboards connected to ports 0x60 and 0x64. This
@@ -170,6 +174,10 @@ emulation and add `keyboard=legacy` on the boot command line.
 you enable the Compatibility System Module (CSM) in the BIOS setup. Others
 only support it when actually booting in legacy mode.
 
+Many USB devices don't fully conform to the USB specification. If the USB
+keyboard probe hangs or fails to detect your keyboard, try the various
+workarounds provided by the "usbinit" boot option.
+
 **NOTE**: Memtest86+'s USB device drivers are work in progress. Not all USB
 devices are supported yet, and there may be problems on some hardware.
 

app/config.c

@@ -175,9 +175,6 @@ static void parse_option(const char *option, const char *params)
             keyboard_types = KT_LEGACY;
         } else if (strncmp(params, "usb", 4) == 0) {
             keyboard_types = KT_USB;
-        } else if (strncmp(params, "buggy-usb", 10) == 0) {
-            keyboard_types = KT_USB;
-            usb_init_options |= USB_EXTRA_RESET;
         }
     } else if (strncmp(option, "powersave", 10) == 0) {
         if (strncmp(params, "off", 4) == 0) {
@@ -201,6 +198,14 @@ static void parse_option(const char *option, const char *params)
         enable_trace = true;
     } else if (strncmp(option, "usbdebug", 9) == 0) {
         usb_init_options |= USB_DEBUG;
+    } else if (strncmp(option, "usbinit", 8) == 0) {
+        if (strncmp(params, "1", 2) == 0) {
+            usb_init_options |= USB_2_STEP_INIT;
+        } else if (strncmp(params, "2", 2) == 0) {
+            usb_init_options |= USB_EXTRA_RESET;
+        } else if (strncmp(params, "3", 2) == 0) {
+            usb_init_options |= USB_2_STEP_INIT|USB_EXTRA_RESET;
+        }
     } else if (strncmp(option, "nosm", 5) == 0) {
         enable_sm = false;
     }

system/usbhcd.c

@@ -543,12 +543,12 @@ bool assign_usb_address(const usb_hcd_t *hcd, const usb_hub_t *hub, int port_num
     ep0->max_packet_size = default_max_packet_size(device_speed);
     ep0->interval        = 0;
 
-    // The device should currently be in Default state. For loww and full speed devices, We first fetch the first
+    // The device should currently be in Default state. For low and full speed devices, we first fetch the first
     // 8 bytes of the device descriptor to discover the maximum packet size for the control endpoint. We then set
     // the device address, which moves the device into Address state, and fetch the full device descriptor.
 
     size_t fetch_length = sizeof(usb_device_desc_t);
-    if (device_speed < USB_SPEED_HIGH) {
+    if (device_speed < USB_SPEED_HIGH || usb_init_options & USB_2_STEP_INIT) {
         fetch_length = 8;
         goto fetch_descriptor;
     }

system/usbhcd.h

@@ -121,7 +121,8 @@ typedef enum {
     USB_DEFAULT_INIT    = 0,
     USB_EXTRA_RESET     = 1 << 0,
     USB_IGNORE_EHCI     = 1 << 1,
-    USB_DEBUG           = 1 << 2
+    USB_2_STEP_INIT     = 1 << 2,
+    USB_DEBUG           = 1 << 3
 } usb_init_options_t;
 
 /**