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Subject[PATCH 08/10] ehci-dbgp: errata for EHCI debug controller initialization
Date
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: Greg KH <gregkh@suse.de>
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
---
drivers/usb/early/ehci-dbgp.c | 23 ++++++++++++++++++++++-
include/linux/usb/ehci_def.h | 1 +
2 files changed, 23 insertions(+), 1 deletions(-)

diff --git a/drivers/usb/early/ehci-dbgp.c b/drivers/usb/early/ehci-dbgp.c
index b88cb65..f0a41c6 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;
}
diff --git a/include/linux/usb/ehci_def.h b/include/linux/usb/ehci_def.h
index 279d48b..209cf36 100644
--- 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)
--
1.6.0.3.523.g304d0


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