[PATCH] USB: EHCI port tweaks

One change may improve some S1 or S3 resume cases, and the other
seems mostly to explain some strange state "lsusb" would show.
Two fixes:

  - On resume, don't think about resuming any unpowered port, or
    resetting any port with OWNER set to the OHCI/UHCI companion.
    This will make some S1 and S3 resume scenarios work better.

  - PORT_CSC was not being cleared correctly in ehci_hub_status_data.
    This was visible at least through current versions of "lsusb",
    and might have caused some other hub related strangeness.

    The fix addresses all three write-to-clear bits, using the same
    approach that UHCI happens to use:  a mask of bits that are
    cleared in most writes to that port status register.

Original patch seems to have been from from William.Morrow@amd.com
and this version (from David) finishes the write-to-clear changes.

Signed-off-by: Jordan Crouse <jordan.crouse@amd.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 23 insertions, 13 deletions

diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 2507e898af0..2f7037c62e8 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -759,12 +759,16 @@ static int ehci_resume (struct usb_hcd *hcd)
         if (time_before (jiffies, ehci->next_statechange))
                 msleep (100);
 
-        /* If any port is suspended, we know we can/must resume the HC. */
+        /* If any port is suspended (or owned by the companion),
+         * we know we can/must resume the HC (and mustn't reset it).
+         */
         for (port = HCS_N_PORTS (ehci->hcs_params); port > 0; ) {
                 u32     status;
                 port--;
                 status = readl (&ehci->regs->port_status [port]);
-                if (status & PORT_SUSPEND) {
+                if (!(status & PORT_POWER))
+                        continue;
+                if (status & (PORT_SUSPEND | PORT_OWNER)) {
                         down (&hcd->self.root_hub->serialize);
                         retval = ehci_hub_resume (hcd);
                         up (&hcd->self.root_hub->serialize);
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index 36cc1f2218d..18d3f227031 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -54,7 +54,7 @@ static int ehci_hub_suspend (struct usb_hcd *hcd)
         /* suspend any active/unsuspended ports, maybe allow wakeup */
         while (port--) {
                 u32 __iomem     *reg = &ehci->regs->port_status [port];
-                u32             t1 = readl (reg);
+                u32             t1 = readl (reg) & ~PORT_RWC_BITS;
                 u32             t2 = t1;
 
                 if ((t1 & PORT_PE) && !(t1 & PORT_OWNER))
@@ -115,7 +115,8 @@ static int ehci_hub_resume (struct usb_hcd *hcd)
         i = HCS_N_PORTS (ehci->hcs_params);
         while (i--) {
                 temp = readl (&ehci->regs->port_status [i]);
-                temp &= ~(PORT_WKOC_E|PORT_WKDISC_E|PORT_WKCONN_E);
+                temp &= ~(PORT_RWC_BITS
+                        | PORT_WKOC_E | PORT_WKDISC_E | PORT_WKCONN_E);
                 if (temp & PORT_SUSPEND) {
                         ehci->reset_done [i] = jiffies + msecs_to_jiffies (20);
                         temp |= PORT_RESUME;
@@ -128,7 +129,7 @@ static int ehci_hub_resume (struct usb_hcd *hcd)
                 temp = readl (&ehci->regs->port_status [i]);
                 if ((temp & PORT_SUSPEND) == 0)
                         continue;
-                temp &= ~PORT_RESUME;
+                temp &= ~(PORT_RWC_BITS | PORT_RESUME);
                 writel (temp, &ehci->regs->port_status [i]);
                 ehci_vdbg (ehci, "resumed port %d\n", i + 1);
         }
@@ -191,6 +192,7 @@ static int check_reset_complete (
 
                 // what happens if HCS_N_CC(params) == 0 ?
                 port_status |= PORT_OWNER;
+                port_status &= ~PORT_RWC_BITS;
                 writel (port_status, &ehci->regs->port_status [index]);
 
         } else
@@ -233,7 +235,8 @@ ehci_hub_status_data (struct usb_hcd *hcd, char *buf)
                 if (temp & PORT_OWNER) {
                         /* don't report this in GetPortStatus */
                         if (temp & PORT_CSC) {
-                                temp &= ~PORT_CSC;
+                                temp &= ~PORT_RWC_BITS;
+                                temp |= PORT_CSC;
                                 writel (temp, &ehci->regs->port_status [i]);
                         }
                         continue;
@@ -343,7 +346,7 @@ static int ehci_hub_control (
                                 &ehci->regs->port_status [wIndex]);
                         break;
                 case USB_PORT_FEAT_C_ENABLE:
-                        writel (temp | PORT_PEC,
+                        writel((temp & ~PORT_RWC_BITS) | PORT_PEC,
                                 &ehci->regs->port_status [wIndex]);
                         break;
                 case USB_PORT_FEAT_SUSPEND:
@@ -353,7 +356,8 @@ static int ehci_hub_control (
                                 if ((temp & PORT_PE) == 0)
                                         goto error;
                                 /* resume signaling for 20 msec */
-                                writel ((temp & ~PORT_WAKE_BITS) | PORT_RESUME,
+                                temp &= ~(PORT_RWC_BITS | PORT_WAKE_BITS);
+                                writel (temp | PORT_RESUME,
                                         &ehci->regs->port_status [wIndex]);
                                 ehci->reset_done [wIndex] = jiffies
                                                 + msecs_to_jiffies (20);
@@ -364,15 +368,15 @@ static int ehci_hub_control (
                         break;
                 case USB_PORT_FEAT_POWER:
                         if (HCS_PPC (ehci->hcs_params))
-                                writel (temp & ~PORT_POWER,
+                                writel (temp & ~(PORT_RWC_BITS | PORT_POWER),
                                         &ehci->regs->port_status [wIndex]);
                         break;
                 case USB_PORT_FEAT_C_CONNECTION:
-                        writel (temp | PORT_CSC,
+                        writel((temp & ~PORT_RWC_BITS) | PORT_CSC,
                                 &ehci->regs->port_status [wIndex]);
                         break;
                 case USB_PORT_FEAT_C_OVER_CURRENT:
-                        writel (temp | PORT_OCC,
+                        writel((temp & ~PORT_RWC_BITS) | PORT_OCC,
                                 &ehci->regs->port_status [wIndex]);
                         break;
                 case USB_PORT_FEAT_C_RESET:
@@ -416,7 +420,7 @@ static int ehci_hub_control (
 
                         /* stop resume signaling */
                         temp = readl (&ehci->regs->port_status [wIndex]);
-                        writel (temp & ~PORT_RESUME,
+                        writel (temp & ~(PORT_RWC_BITS | PORT_RESUME),
                                 &ehci->regs->port_status [wIndex]);
                         retval = handshake (
                                         &ehci->regs->port_status [wIndex],
@@ -437,7 +441,7 @@ static int ehci_hub_control (
                         ehci->reset_done [wIndex] = 0;
 
                         /* force reset to complete */
-                        writel (temp & ~PORT_RESET,
+                        writel (temp & ~(PORT_RWC_BITS | PORT_RESET),
                                         &ehci->regs->port_status [wIndex]);
                         /* REVISIT:  some hardware needs 550+ usec to clear
                          * this bit; seems too long to spin routinely...
@@ -500,6 +504,7 @@ static int ehci_hub_control (
                 if (temp & PORT_OWNER)
                         break;
 
+                temp &= ~PORT_RWC_BITS;
                 switch (wValue) {
                 case USB_PORT_FEAT_SUSPEND:
                         if ((temp & PORT_PE) == 0
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 20c9b550097..f34a0516d35 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -263,6 +263,7 @@ struct ehci_regs {
 #define PORT_PE         (1<<2)          /* port enable */
 #define PORT_CSC        (1<<1)          /* connect status change */
 #define PORT_CONNECT    (1<<0)          /* device connected */
+#define PORT_RWC_BITS   (PORT_CSC | PORT_PEC | PORT_OCC)
 } __attribute__ ((packed));
 
 /* Appendix C, Debug port ... intended for use with special "debug devices"