USB: ehci-dbgp: split PID register updates for IN and OUT pipes

This patch addresses two problems:

1) Bulk reads should always use the DATA0 for the pid, and the write
   PID should toggle between DATA0 and DATA1.  The fix is using
   dbgp_pid_write_update() and dbgp_pid_read_update().

2) The delay loop for waiting for a transaction was not long enough to
   always complete the initial handshake inside dbgp_wait_until_done().
   After the initial handshake the maximum delay length is never reached.

The combined result of these two changes allows for the removal of the
forced resynchronization where a bulk write was issued with a dummy
data payload only to get the device to start accepting data writes
again.

CC: Eric Biederman <ebiederm@xmission.com>
CC: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 28 insertions, 40 deletions

diff --git a/drivers/usb/early/ehci-dbgp.c b/drivers/usb/early/ehci-dbgp.c
index 2958a1271b20..6e98a3697844 100644
--- a/drivers/usb/early/ehci-dbgp.c
+++ b/drivers/usb/early/ehci-dbgp.c
@@ -66,8 +66,6 @@ static struct ehci_dev ehci_dev;
 
 #define USB_DEBUG_DEVNUM 127
 
-#define DBGP_DATA_TOGGLE        0x8800
-
 #ifdef DBGP_DEBUG
 #define dbgp_printk printk
 static void dbgp_ehci_status(char *str)
@@ -88,11 +86,6 @@ static inline void dbgp_ehci_status(char *str) { }
 static inline void dbgp_printk(const char *fmt, ...) { }
 #endif
 
-static inline u32 dbgp_pid_update(u32 x, u32 tok)
-{
-        return ((x ^ DBGP_DATA_TOGGLE) & 0xffff00) | (tok & 0xff);
-}
-
 static inline u32 dbgp_len_update(u32 x, u32 len)
 {
         return (x & ~0x0f) | (len & 0x0f);
@@ -136,6 +129,19 @@ static inline u32 dbgp_len_update(u32 x, u32 len)
 
 #define DBGP_MAX_PACKET         8
 #define DBGP_TIMEOUT            (250 * 1000)
+#define DBGP_LOOPS              1000
+
+static inline u32 dbgp_pid_write_update(u32 x, u32 tok)
+{
+        static int data0 = USB_PID_DATA1;
+        data0 ^= USB_PID_DATA_TOGGLE;
+        return (x & 0xffff0000) | (data0 << 8) | (tok & 0xff);
+}
+
+static inline u32 dbgp_pid_read_update(u32 x, u32 tok)
+{
+        return (x & 0xffff0000) | (USB_PID_DATA0 << 8) | (tok & 0xff);
+}
 
 static int dbgp_wait_until_complete(void)
 {
@@ -180,7 +186,7 @@ static int dbgp_wait_until_done(unsigned ctrl)
 {
         u32 pids, lpid;
         int ret;
-        int loop = 3;
+        int loop = DBGP_LOOPS;
 
 retry:
         writel(ctrl | DBGP_GO, &ehci_debug->control);
@@ -197,6 +203,8 @@ retry:
                  */
                 if (ret == -DBGP_TIMEOUT && !dbgp_not_safe)
                         dbgp_not_safe = 1;
+                if (ret == -DBGP_ERR_BAD && --loop > 0)
+                        goto retry;
                 return ret;
         }
 
@@ -245,12 +253,20 @@ static inline void dbgp_get_data(void *buf, int size)
                 bytes[i] = (hi >> (8*(i - 4))) & 0xff;
 }
 
-static int dbgp_out(u32 addr, const char *bytes, int size)
+static int dbgp_bulk_write(unsigned devnum, unsigned endpoint,
+                         const char *bytes, int size)
 {
+        int ret;
+        u32 addr;
         u32 pids, ctrl;
 
+        if (size > DBGP_MAX_PACKET)
+                return -1;
+
+        addr = DBGP_EPADDR(devnum, endpoint);
+
         pids = readl(&ehci_debug->pids);
-        pids = dbgp_pid_update(pids, USB_PID_OUT);
+        pids = dbgp_pid_write_update(pids, USB_PID_OUT);
 
         ctrl = readl(&ehci_debug->control);
         ctrl = dbgp_len_update(ctrl, size);
@@ -260,34 +276,7 @@ static int dbgp_out(u32 addr, const char *bytes, int size)
         dbgp_set_data(bytes, size);
         writel(addr, &ehci_debug->address);
         writel(pids, &ehci_debug->pids);
-        return dbgp_wait_until_done(ctrl);
-}
-
-static int dbgp_bulk_write(unsigned devnum, unsigned endpoint,
-                         const char *bytes, int size)
-{
-        int ret;
-        int loops = 5;
-        u32 addr;
-        if (size > DBGP_MAX_PACKET)
-                return -1;
-
-        addr = DBGP_EPADDR(devnum, endpoint);
-try_again:
-        if (loops--) {
-                ret = dbgp_out(addr, bytes, size);
-                if (ret == -DBGP_ERR_BAD) {
-                        int try_loops = 3;
-                        do {
-                                /* Emit a dummy packet to re-sync communication
-                                 * with the debug device */
-                                if (dbgp_out(addr, "12345678", 8) >= 0) {
-                                        udelay(2);
-                                        goto try_again;
-                                }
-                        } while (try_loops--);
-                }
-        }
+        ret = dbgp_wait_until_done(ctrl);
 
         return ret;
 }
@@ -304,7 +293,7 @@ static int dbgp_bulk_read(unsigned devnum, unsigned endpoint, void *data,
         addr = DBGP_EPADDR(devnum, endpoint);
 
         pids = readl(&ehci_debug->pids);
-        pids = dbgp_pid_update(pids, USB_PID_IN);
+        pids = dbgp_pid_read_update(pids, USB_PID_IN);
 
         ctrl = readl(&ehci_debug->control);
         ctrl = dbgp_len_update(ctrl, size);
@@ -362,7 +351,6 @@ static int dbgp_control_msg(unsigned devnum, int requesttype,
         return dbgp_bulk_read(devnum, 0, data, size);
 }
 
-
 /* Find a PCI capability */
 static u32 __init find_cap(u32 num, u32 slot, u32 func, int cap)
 {