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>

1 files changed, 22 insertions, 1 deletions

diff --git a/drivers/usb/early/ehci-dbgp.c b/drivers/usb/early/ehci-dbgp.c
index b88cb65b64e0..f0a41c647bef 100644
--- 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;
         }