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, 10 insertions, 6 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index a87c0573c860..de1e689d3df0 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -226,8 +226,13 @@ static int ehci_halt (struct ehci_hcd *ehci)
         if ((temp & STS_HALT) != 0)
                 return 0;
 
+        /*
+         * This routine gets called during probe before ehci->command
+         * has been initialized, so we can't rely on its value.
+         */
+        ehci->command &= ~CMD_RUN;
         temp = ehci_readl(ehci, &ehci->regs->command);
-        temp &= ~CMD_RUN;
+        temp &= ~(CMD_RUN | CMD_IAAD);
         ehci_writel(ehci, temp, &ehci->regs->command);
         return handshake (ehci, &ehci->regs->status,
                           STS_HALT, STS_HALT, 16 * 125);
@@ -347,6 +352,7 @@ static int ehci_reset (struct ehci_hcd *ehci)
         if (ehci->debug)
                 dbgp_external_startup();
 
+        ehci->command = ehci_readl(ehci, &ehci->regs->command);
         ehci->port_c_suspend = ehci->suspended_ports =
                         ehci->resuming_ports = 0;
         return retval;
@@ -363,16 +369,14 @@ static void ehci_quiesce (struct ehci_hcd *ehci)
 #endif
 
         /* wait for any schedule enables/disables to take effect */
-        temp = ehci_readl(ehci, &ehci->regs->command) << 10;
-        temp &= STS_ASS | STS_PSS;
+        temp = (ehci->command << 10) & (STS_ASS | STS_PSS);
         if (handshake_on_error_set_halt(ehci, &ehci->regs->status,
                                         STS_ASS | STS_PSS, temp, 16 * 125))
                 return;
 
         /* then disable anything that's still active */
-        temp = ehci_readl(ehci, &ehci->regs->command);
-        temp &= ~(CMD_ASE | CMD_IAAD | CMD_PSE);
-        ehci_writel(ehci, temp, &ehci->regs->command);
+        ehci->command &= ~(CMD_ASE | CMD_PSE);
+        ehci_writel(ehci, ehci->command, &ehci->regs->command);
 
         /* hardware can take 16 microframes to turn off ... */
         handshake_on_error_set_halt(ehci, &ehci->regs->status,