USB: ehci-dbgp: errata for EHCI debug controller initialization

On some EHCI usb debug controllers, the EHCI debug device will fail to
be seen after a port reset, after a warm reset.  Two options exist to
get the device to initialize correctly.

Option 1 is to unplug and plug in the device.

Option 2 is to use the EHCI port test to get the usb debug device to
start talking again.  At that point the debug controller port reset
will succeed.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
CC: dbrownell@users.sourceforge.net
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/early/ehci-dbgp.c b/drivers/usb/early/ehci-dbgp.c
index b88cb65..f0a41c6 100644 (file)
--- a/drivers/usb/early/ehci-dbgp.c
+++ b/drivers/usb/early/ehci-dbgp.c
@@ -478,10 +478,13 @@ int dbgp_external_startup(void)
        int devnum;
        struct usb_debug_descriptor dbgp_desc;
        int ret;
-       u32 ctrl, portsc;
+       u32 ctrl, portsc, cmd;
        int dbg_port = dbgp_phys_port;
        int tries = 3;
+       int reset_port_tries = 1;
+       int try_hard_once = 1;
 
+try_port_reset_again:
        ret = dbgp_ehci_startup();
        if (ret)
                return ret;
@@ -490,6 +493,24 @@ int dbgp_external_startup(void)
        ret = ehci_wait_for_port(dbg_port);
        if (ret < 0) {
                portsc = readl(&ehci_regs->port_status[dbg_port - 1]);
+               if (!(portsc & PORT_CONNECT) && try_hard_once) {
+                       /* Last ditch effort to try to force enable
+                        * the debug device by using the packet test
+                        * ehci command to try and wake it up. */
+                       try_hard_once = 0;
+                       cmd = readl(&ehci_regs->command);
+                       cmd &= ~CMD_RUN;
+                       writel(cmd, &ehci_regs->command);
+                       portsc = readl(&ehci_regs->port_status[dbg_port - 1]);
+                       portsc |= PORT_TEST_PKT;
+                       writel(portsc, &ehci_regs->port_status[dbg_port - 1]);
+                       dbgp_ehci_status("Trying to force debug port online");
+                       mdelay(50);
+                       dbgp_ehci_controller_reset();
+                       goto try_port_reset_again;
+               } else if (reset_port_tries--) {
+                       goto try_port_reset_again;
+               }
                dbgp_printk("No device found in debug port\n");
                return -EIO;
        }

diff --git a/include/linux/usb/ehci_def.h b/include/linux/usb/ehci_def.h
index 1909d92..af4b86f 100644 (file)
--- a/include/linux/usb/ehci_def.h
+++ b/include/linux/usb/ehci_def.h
@@ -105,6 +105,7 @@ struct ehci_regs {
 #define PORT_WKDISC_E  (1<<21)         /* wake on disconnect (enable) */
 #define PORT_WKCONN_E  (1<<20)         /* wake on connect (enable) */
 /* 19:16 for port testing */
+#define PORT_TEST_PKT  (0x4<<16)       /* Port Test Control - packet test */
 #define PORT_LED_OFF   (0<<14)
 #define PORT_LED_AMBER (1<<14)
 #define PORT_LED_GREEN (2<<14)