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>

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;

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,

drivers/usb/host/ehci-hub.c

@@ -233,7 +233,6 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
 	/* stop schedules, clean any completed work */
 	if (ehci->rh_state == EHCI_RH_RUNNING)
 		ehci_quiesce (ehci);
-	ehci->command = ehci_readl(ehci, &ehci->regs->command);
 	ehci_work(ehci);
 
 	/* Unlike other USB host controller types, EHCI doesn't have
@@ -374,6 +373,7 @@ static int ehci_bus_resume (struct usb_hcd *hcd)
 	ehci_writel(ehci, (u32) ehci->async->qh_dma, &ehci->regs->async_next);
 
 	/* restore CMD_RUN, framelist size, and irq threshold */
+	ehci->command |= CMD_RUN;
 	ehci_writel(ehci, ehci->command, &ehci->regs->command);
 	ehci->rh_state = EHCI_RH_RUNNING;
 

drivers/usb/host/ehci-q.c

@@ -981,14 +981,12 @@ static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 	head = ehci->async;
 	timer_action_done (ehci, TIMER_ASYNC_OFF);
 	if (!head->qh_next.qh) {
-		u32	cmd = ehci_readl(ehci, &ehci->regs->command);
-
-		if (!(cmd & CMD_ASE)) {
+		if (!(ehci->command & CMD_ASE)) {
 			/* in case a clear of CMD_ASE didn't take yet */
 			(void)handshake(ehci, &ehci->regs->status,
 					STS_ASS, 0, 150);
-			cmd |= CMD_ASE;
-			ehci_writel(ehci, cmd, &ehci->regs->command);
+			ehci->command |= CMD_ASE;
+			ehci_writel(ehci, ehci->command, &ehci->regs->command);
 			/* posted write need not be known to HC yet ... */
 		}
 	}
@@ -1204,7 +1202,6 @@ static void end_unlink_async (struct ehci_hcd *ehci)
 
 static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 {
-	int		cmd = ehci_readl(ehci, &ehci->regs->command);
 	struct ehci_qh	*prev;
 
 #ifdef DEBUG
@@ -1222,8 +1219,8 @@ static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 		if (ehci->rh_state != EHCI_RH_HALTED
 				&& !ehci->reclaim) {
 			/* ... and CMD_IAAD clear */
-			ehci_writel(ehci, cmd & ~CMD_ASE,
-				    &ehci->regs->command);
+			ehci->command &= ~CMD_ASE;
+			ehci_writel(ehci, ehci->command, &ehci->regs->command);
 			wmb ();
 			// handshake later, if we need to
 			timer_action_done (ehci, TIMER_ASYNC_OFF);
@@ -1253,8 +1250,7 @@ static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 		return;
 	}
 
-	cmd |= CMD_IAAD;
-	ehci_writel(ehci, cmd, &ehci->regs->command);
+	ehci_writel(ehci, ehci->command | CMD_IAAD, &ehci->regs->command);
 	(void)ehci_readl(ehci, &ehci->regs->command);
 	iaa_watchdog_start(ehci);
 }

drivers/usb/host/ehci-sched.c

@@ -481,7 +481,6 @@ static int tt_no_collision (
 
 static int enable_periodic (struct ehci_hcd *ehci)
 {
-	u32	cmd;
 	int	status;
 
 	if (ehci->periodic_sched++)
@@ -497,8 +496,8 @@ static int enable_periodic (struct ehci_hcd *ehci)
 		return status;
 	}
 
-	cmd = ehci_readl(ehci, &ehci->regs->command) | CMD_PSE;
-	ehci_writel(ehci, cmd, &ehci->regs->command);
+	ehci->command |= CMD_PSE;
+	ehci_writel(ehci, ehci->command, &ehci->regs->command);
 	/* posted write ... PSS happens later */
 
 	/* make sure ehci_work scans these */
@@ -511,7 +510,6 @@ static int enable_periodic (struct ehci_hcd *ehci)
 
 static int disable_periodic (struct ehci_hcd *ehci)
 {
-	u32	cmd;
 	int	status;
 
 	if (--ehci->periodic_sched)
@@ -537,8 +535,8 @@ static int disable_periodic (struct ehci_hcd *ehci)
 		return status;
 	}
 
-	cmd = ehci_readl(ehci, &ehci->regs->command) & ~CMD_PSE;
-	ehci_writel(ehci, cmd, &ehci->regs->command);
+	ehci->command &= ~CMD_PSE;
+	ehci_writel(ehci, ehci->command, &ehci->regs->command);
 	/* posted write ... */
 
 	free_cached_lists(ehci);