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authorJason Wessel <jason.wessel@windriver.com>2009-08-21 00:39:55 +0400
committerGreg Kroah-Hartman <gregkh@suse.de>2009-09-23 17:46:38 +0400
commitaab2d4086a1876fcff282aa36e2d4a92aa9935c9 (patch)
tree3b1bb3d934bec91c44eaf61aadb6c624eb8dd9b3 /drivers
parent8d053c79f22462f55c02c8083580730b922cf7b4 (diff)
downloadlinux-aab2d4086a1876fcff282aa36e2d4a92aa9935c9.tar.xz
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/usb/early/ehci-dbgp.c23
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;
}