[PATCH] UHCI: use integer-sized frame numbers
This patch (as687) changes uhci-hcd to keep track of frame numbers as
full-sized integers rather than 11-bit values. This makes them a lot
easier to handle and makes it possible to schedule beyond a 2-second
window, should anyone ever want to do so.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c
index 395402e..5e75ad6d 100644
--- a/drivers/usb/host/uhci-hcd.c
+++ b/drivers/usb/host/uhci-hcd.c
@@ -13,7 +13,7 @@
* (C) Copyright 2000 Yggdrasil Computing, Inc. (port of new PCI interface
* support from usb-ohci.c by Adam Richter, adam@yggdrasil.com).
* (C) Copyright 1999 Gregory P. Smith (from usb-ohci.c)
- * (C) Copyright 2004-2005 Alan Stern, stern@rowland.harvard.edu
+ * (C) Copyright 2004-2006 Alan Stern, stern@rowland.harvard.edu
*
* Intel documents this fairly well, and as far as I know there
* are no royalties or anything like that, but even so there are
@@ -31,7 +31,6 @@
#include <linux/ioport.h>
#include <linux/sched.h>
#include <linux/slab.h>
-#include <linux/smp_lock.h>
#include <linux/errno.h>
#include <linux/unistd.h>
#include <linux/interrupt.h>
@@ -146,7 +145,8 @@
outl(uhci->frame_dma_handle, uhci->io_addr + USBFLBASEADD);
/* Set the current frame number */
- outw(uhci->frame_number, uhci->io_addr + USBFRNUM);
+ outw(uhci->frame_number & UHCI_MAX_SOF_NUMBER,
+ uhci->io_addr + USBFRNUM);
/* Mark controller as not halted before we enable interrupts */
uhci_to_hcd(uhci)->state = HC_STATE_SUSPENDED;
@@ -239,7 +239,6 @@
dev_warn(uhci_dev(uhci), "Controller not stopped yet!\n");
uhci_get_current_frame_number(uhci);
- smp_wmb();
uhci->rh_state = new_state;
uhci->is_stopped = UHCI_IS_STOPPED;
@@ -253,7 +252,6 @@
{
uhci_to_hcd(uhci)->state = HC_STATE_RUNNING;
uhci->is_stopped = 0;
- smp_wmb();
/* Mark it configured and running with a 64-byte max packet.
* All interrupts are enabled, even though RESUME won't do anything.
@@ -360,12 +358,21 @@
/*
* Store the current frame number in uhci->frame_number if the controller
- * is runnning
+ * is runnning. Expand from 11 bits (of which we use only 10) to a
+ * full-sized integer.
+ *
+ * Like many other parts of the driver, this code relies on being polled
+ * more than once per second as long as the controller is running.
*/
static void uhci_get_current_frame_number(struct uhci_hcd *uhci)
{
- if (!uhci->is_stopped)
- uhci->frame_number = inw(uhci->io_addr + USBFRNUM);
+ if (!uhci->is_stopped) {
+ unsigned delta;
+
+ delta = (inw(uhci->io_addr + USBFRNUM) - uhci->frame_number) &
+ (UHCI_NUMFRAMES - 1);
+ uhci->frame_number += delta;
+ }
}
/*
@@ -798,18 +805,15 @@
static int uhci_hcd_get_frame_number(struct usb_hcd *hcd)
{
struct uhci_hcd *uhci = hcd_to_uhci(hcd);
- unsigned long flags;
- int is_stopped;
- int frame_number;
+ unsigned frame_number;
+ unsigned delta;
/* Minimize latency by avoiding the spinlock */
- local_irq_save(flags);
- is_stopped = uhci->is_stopped;
- smp_rmb();
- frame_number = (is_stopped ? uhci->frame_number :
- inw(uhci->io_addr + USBFRNUM));
- local_irq_restore(flags);
- return frame_number;
+ frame_number = uhci->frame_number;
+ barrier();
+ delta = (inw(uhci->io_addr + USBFRNUM) - frame_number) &
+ (UHCI_NUMFRAMES - 1);
+ return frame_number + delta;
}
static const char hcd_name[] = "uhci_hcd";