[Qemu-devel] [PATCH 5/5] usb-tablet: Allow connecting to ehci

[Hans de Goede <hdegoede@redhat.com>]

Our ehci code has is capable of significantly lowering the wakeup rate
for the hcd emulation while the device is idle. It is possible to add
similar code ot the uhci emulation, but that simply is not there atm,
and there is no reason why a (virtual) usb-tablet can not be a USB-2 device.

Making usb-hid devices connect to the emulated ehci controller instead
of the emulated uhci controller on vms which have both lowers the cpuload
for a fully idle vm from 20% to 2-3% (on my laptop).

An alternative implementation to using a property to select the tablet
type, would be simply making it a new device type, ie usb-tablet2, but the
downside of that is that this will require libvirt changes to be available
through libvirt at all, and then management tools changes to become the
default for new vms, where as using a property will automatically get
any pc-1.3 type vms the lower cpuload.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 hw/pc_piix.c     |  4 +++
 hw/usb/dev-hid.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 88 insertions(+), 1 deletion(-)

diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index cfa839c..3754e21 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -386,6 +386,10 @@ static QEMUMachine pc_machine_v1_3 = {
             .driver   = "VGA",\
             .property = "mmio",\
             .value    = "off",\
+        },{\
+            .driver   = "usb-tablet",\
+            .property = "usb_version",\
+            .value    = stringify(1),\
         }
 
 static QEMUMachine pc_machine_v1_2 = {
diff --git a/hw/usb/dev-hid.c b/hw/usb/dev-hid.c
index 55266b1..8749128 100644
--- a/hw/usb/dev-hid.c
+++ b/hw/usb/dev-hid.c
@@ -46,6 +46,7 @@ typedef struct USBHIDState {
     USBDevice dev;
     USBEndpoint *intr;
     HIDState hid;
+    uint32_t usb_version;
 } USBHIDState;
 
 enum {
@@ -131,6 +132,36 @@ static const USBDescIface desc_iface_tablet = {
     },
 };
 
+static const USBDescIface desc_iface_tablet2 = {
+    .bInterfaceNumber              = 0,
+    .bNumEndpoints                 = 1,
+    .bInterfaceClass               = USB_CLASS_HID,
+    .bInterfaceProtocol            = 0x02,
+    .ndesc                         = 1,
+    .descs = (USBDescOther[]) {
+        {
+            /* HID descriptor */
+            .data = (uint8_t[]) {
+                0x09,          /*  u8  bLength */
+                USB_DT_HID,    /*  u8  bDescriptorType */
+                0x01, 0x00,    /*  u16 HID_class */
+                0x00,          /*  u8  country_code */
+                0x01,          /*  u8  num_descriptors */
+                USB_DT_REPORT, /*  u8  type: Report */
+                74, 0,         /*  u16 len */
+            },
+        },
+    },
+    .eps = (USBDescEndpoint[]) {
+        {
+            .bEndpointAddress      = USB_DIR_IN | 0x01,
+            .bmAttributes          = USB_ENDPOINT_XFER_INT,
+            .wMaxPacketSize        = 8,
+            .bInterval             = 4, /* 2 ^ (4-1) * 125 usecs = 1 ms */
+        },
+    },
+};
+
 static const USBDescIface desc_iface_keyboard = {
     .bInterfaceNumber              = 0,
     .bNumEndpoints                 = 1,
@@ -196,6 +227,23 @@ static const USBDescDevice desc_device_tablet = {
     },
 };
 
+static const USBDescDevice desc_device_tablet2 = {
+    .bcdUSB                        = 0x0200,
+    .bMaxPacketSize0               = 64,
+    .bNumConfigurations            = 1,
+    .confs = (USBDescConfig[]) {
+        {
+            .bNumInterfaces        = 1,
+            .bConfigurationValue   = 1,
+            .iConfiguration        = STR_CONFIG_TABLET,
+            .bmAttributes          = 0xa0,
+            .bMaxPower             = 50,
+            .nif = 1,
+            .ifs = &desc_iface_tablet2,
+        },
+    },
+};
+
 static const USBDescDevice desc_device_keyboard = {
     .bcdUSB                        = 0x0100,
     .bMaxPacketSize0               = 8,
@@ -239,6 +287,20 @@ static const USBDesc desc_tablet = {
     .str  = desc_strings,
 };
 
+static const USBDesc desc_tablet2 = {
+    .id = {
+        .idVendor          = 0x0627,
+        .idProduct         = 0x0001,
+        .bcdDevice         = 0,
+        .iManufacturer     = STR_MANUFACTURER,
+        .iProduct          = STR_PRODUCT_TABLET,
+        .iSerialNumber     = STR_SERIALNUMBER,
+    },
+    .full = &desc_device_tablet,
+    .high = &desc_device_tablet2,
+    .str  = desc_strings,
+};
+
 static const USBDesc desc_keyboard = {
     .id = {
         .idVendor          = 0x0627,
@@ -508,6 +570,21 @@ static int usb_hid_initfn(USBDevice *dev, int kind)
 
 static int usb_tablet_initfn(USBDevice *dev)
 {
+    USBHIDState *us = DO_UPCAST(USBHIDState, dev, dev);
+
+    switch (us->usb_version) {
+    case 1:
+        dev->usb_desc = &desc_tablet;
+        break;
+    case 2:
+        dev->usb_desc = &desc_tablet2;
+        break;
+    default:
+        error_report("Invalid usb version %d for usb-tabler (must be 1 or 2)",
+                     us->usb_version);
+        return -1;
+    }
+
     return usb_hid_initfn(dev, HID_TABLET);
 }
 
@@ -562,8 +639,14 @@ static void usb_hid_class_initfn(ObjectClass *klass, void *data)
     uc->handle_control = usb_hid_handle_control;
     uc->handle_data    = usb_hid_handle_data;
     uc->handle_destroy = usb_hid_handle_destroy;
+    uc->handle_attach  = usb_desc_attach;
 }
 
+static Property usb_tablet_properties[] = {
+        DEFINE_PROP_UINT32("usb_version", USBHIDState, usb_version, 2),
+        DEFINE_PROP_END_OF_LIST(),
+};
+
 static void usb_tablet_class_initfn(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
@@ -572,8 +655,8 @@ static void usb_tablet_class_initfn(ObjectClass *klass, void *data)
     usb_hid_class_initfn(klass, data);
     uc->init           = usb_tablet_initfn;
     uc->product_desc   = "QEMU USB Tablet";
-    uc->usb_desc       = &desc_tablet;
     dc->vmsd = &vmstate_usb_ptr;
+    dc->props = usb_tablet_properties;
 }
 
 static TypeInfo usb_tablet_info = {
-- 
1.8.0