EHCI: maintain the ehci->command value properly

The ehci-hcd driver is a little haphazard about keeping track of the
state of the USBCMD register.  The ehci->command field is supposed to
hold the register's value (apart from a few special bits) at all
times, but it isn't maintained properly.

This patch (as1543) cleans up the situation.  It keeps ehci->command
up-to-date, and uses that value rather than reading the register from
the hardware whenever possible.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 4 deletions

diff --git a/drivers/usb/host/ehci-dbg.c b/drivers/usb/host/ehci-dbg.c
index 680e1a31fb87..7561966fbdc4 100644
--- a/drivers/usb/host/ehci-dbg.c
+++ b/drivers/usb/host/ehci-dbg.c
@@ -1025,10 +1025,8 @@ static ssize_t debug_lpm_write(struct file *file, const char __user *user_buf,
                 if (strict_strtoul(buf + 5, 16, &hird))
                         return -EINVAL;
                 printk(KERN_INFO "setting hird %s %lu\n", buf + 6, hird);
-                temp = ehci_readl(ehci, &ehci->regs->command);
-                temp &= ~CMD_HIRD;
-                temp |= hird << 24;
-                ehci_writel(ehci, temp, &ehci->regs->command);
+                ehci->command = (ehci->command & ~CMD_HIRD) | (hird << 24);
+                ehci_writel(ehci, ehci->command, &ehci->regs->command);
         } else if (strncmp(buf, "disable", 7) == 0) {
                 if (strict_strtoul(buf + 8, 10, &port))
                         return -EINVAL;