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Commit aab2d408 authored by Jason Wessel's avatar Jason Wessel Committed by Greg Kroah-Hartman
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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: default avatarJason 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: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 8d053c79

drivers/usb/early/ehci-dbgp.c

+22 −1
Original line number Diff line number Diff line
@@ -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;

	}

include/linux/usb/ehci_def.h

+1 −0
Original line number Diff line number Diff line
@@ -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)