[Qemu-devel] [PATCH 12/18] usb-linux: split large xfers

[Gerd Hoffmann <kraxel@redhat.com>]

Add support for splitting large transfers into multiple smaller ones.
This is needed for the upcoming EHCI emulation which allows guests
to submit requests up to 20k in size.  The linux kernel allows 16k
max size though.

Roughly based on a patch from git://git.kiszka.org/qemu.git ehci

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 usb-linux.c |   68 +++++++++++++++++++++++++++++++++++++---------------------
 1 files changed, 43 insertions(+), 25 deletions(-)

diff --git a/usb-linux.c b/usb-linux.c
index b8f7705..b95c119 100644
--- a/usb-linux.c
+++ b/usb-linux.c
@@ -89,6 +89,9 @@ static int usb_fs_type;
 #define ISO_URB_COUNT 3
 #define INVALID_EP_TYPE 255
 
+/* devio.c limits single requests to 16k */
+#define MAX_USBFS_BUFFER_SIZE 16384
+
 typedef struct AsyncURB AsyncURB;
 
 struct endp_data {
@@ -229,6 +232,7 @@ struct AsyncURB
 
     /* For regular async urbs */
     USBPacket     *packet;
+    int more; /* large transfer, more urbs follow */
 
     /* For buffered iso handling */
     int iso_frame_idx; /* -1 means in flight */
@@ -291,7 +295,7 @@ static void async_complete(void *opaque)
         if (p) {
             switch (aurb->urb.status) {
             case 0:
-                p->len = aurb->urb.actual_length;
+                p->len += aurb->urb.actual_length;
                 break;
 
             case -EPIPE:
@@ -306,7 +310,7 @@ static void async_complete(void *opaque)
 
             if (aurb->urb.type == USBDEVFS_URB_TYPE_CONTROL) {
                 usb_generic_async_ctrl_complete(&s->dev, p);
-            } else {
+            } else if (!aurb->more) {
                 usb_packet_complete(&s->dev, p);
             }
         }
@@ -646,7 +650,8 @@ static int usb_host_handle_data(USBDevice *dev, USBPacket *p)
     USBHostDevice *s = DO_UPCAST(USBHostDevice, dev, dev);
     struct usbdevfs_urb *urb;
     AsyncURB *aurb;
-    int ret;
+    int ret, rem;
+    uint8_t *pbuf;
     uint8_t ep;
 
     if (!is_valid(s, p->devep)) {
@@ -673,32 +678,45 @@ static int usb_host_handle_data(USBDevice *dev, USBPacket *p)
         return usb_host_handle_iso_data(s, p, p->pid == USB_TOKEN_IN);
     }
 
-    aurb = async_alloc(s);
-    aurb->packet = p;
+    rem = p->len;
+    pbuf = p->data;
+    p->len = 0;
+    while (rem) {
+        aurb = async_alloc(s);
+        aurb->packet = p;
 
-    urb = &aurb->urb;
+        urb = &aurb->urb;
+        urb->endpoint      = ep;
+        urb->type          = USBDEVFS_URB_TYPE_BULK;
+        urb->usercontext   = s;
+        urb->buffer        = pbuf;
 
-    urb->endpoint      = ep;
-    urb->buffer        = p->data;
-    urb->buffer_length = p->len;
-    urb->type          = USBDEVFS_URB_TYPE_BULK;
-    urb->usercontext   = s;
+        if (rem > MAX_USBFS_BUFFER_SIZE) {
+            urb->buffer_length = MAX_USBFS_BUFFER_SIZE;
+            aurb->more         = 1;
+        } else {
+            urb->buffer_length = rem;
+            aurb->more         = 0;
+        }
+        pbuf += urb->buffer_length;
+        rem  -= urb->buffer_length;
 
-    ret = ioctl(s->fd, USBDEVFS_SUBMITURB, urb);
+        ret = ioctl(s->fd, USBDEVFS_SUBMITURB, urb);
 
-    DPRINTF("husb: data submit. ep 0x%x len %u aurb %p\n",
-            urb->endpoint, p->len, aurb);
+        DPRINTF("husb: data submit: ep 0x%x, len %u, more %d, packet %p, aurb %p\n",
+                urb->endpoint, urb->buffer_length, aurb->more, p, aurb);
 
-    if (ret < 0) {
-        DPRINTF("husb: submit failed. errno %d\n", errno);
-        async_free(aurb);
+        if (ret < 0) {
+            DPRINTF("husb: submit failed. errno %d\n", errno);
+            async_free(aurb);
 
-        switch(errno) {
-        case ETIMEDOUT:
-            return USB_RET_NAK;
-        case EPIPE:
-        default:
-            return USB_RET_STALL;
+            switch(errno) {
+            case ETIMEDOUT:
+                return USB_RET_NAK;
+            case EPIPE:
+            default:
+                return USB_RET_STALL;
+            }
         }
     }
 
-- 
1.7.1