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authorDavid Brownell <dbrownell@users.sourceforge.net>2009-03-31 23:26:10 +0400
committerGreg Kroah-Hartman <gregkh@suse.de>2009-06-16 08:44:40 +0400
commitdef6f8b978618d50daaddb92331d398da9e141f1 (patch)
treeac8de48477184a97fec8cd96fa932b6ca90bb177 /drivers/usb/otg/twl4030-usb.c
parentdc2f2b7505c195a6963fc07b549e269eee417261 (diff)
downloadlinux-def6f8b978618d50daaddb92331d398da9e141f1.tar.xz
USB: twl4030-usb: fix minor reporting goofage
Fix a reporting glitch in the twl4030 USB transceiver code. It wasn't properly distinguishing the two types of active USB link: ID grounded, vs not. In the current code that distinction doesn't much matter; in the future this bugfix should help support better USB controller communications. Provide a comment sorting out some of the cryptic bits of the manual: different sections use different names for key signals, and the register definitions don't help much without the explanations and diagrams. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/otg/twl4030-usb.c')
-rw-r--r--drivers/usb/otg/twl4030-usb.c26
1 files changed, 19 insertions, 7 deletions
diff --git a/drivers/usb/otg/twl4030-usb.c b/drivers/usb/otg/twl4030-usb.c
index c34e63910acb..9e3e7a5c258b 100644
--- a/drivers/usb/otg/twl4030-usb.c
+++ b/drivers/usb/otg/twl4030-usb.c
@@ -217,6 +217,7 @@
/* In module TWL4030_MODULE_PM_MASTER */
#define PROTECT_KEY 0x0E
+#define STS_HW_CONDITIONS 0x0F
/* In module TWL4030_MODULE_PM_RECEIVER */
#define VUSB_DEDICATED1 0x7D
@@ -351,15 +352,26 @@ static enum linkstat twl4030_usb_linkstat(struct twl4030_usb *twl)
int status;
int linkstat = USB_LINK_UNKNOWN;
- /* STS_HW_CONDITIONS */
- status = twl4030_readb(twl, TWL4030_MODULE_PM_MASTER, 0x0f);
+ /*
+ * For ID/VBUS sensing, see manual section 15.4.8 ...
+ * except when using only battery backup power, two
+ * comparators produce VBUS_PRES and ID_PRES signals,
+ * which don't match docs elsewhere. But ... BIT(7)
+ * and BIT(2) of STS_HW_CONDITIONS, respectively, do
+ * seem to match up. If either is true the USB_PRES
+ * signal is active, the OTG module is activated, and
+ * its interrupt may be raised (may wake the system).
+ */
+ status = twl4030_readb(twl, TWL4030_MODULE_PM_MASTER,
+ STS_HW_CONDITIONS);
if (status < 0)
dev_err(twl->dev, "USB link status err %d\n", status);
- else if (status & BIT(7))
- linkstat = USB_LINK_VBUS;
- else if (status & BIT(2))
- linkstat = USB_LINK_ID;
- else
+ else if (status & (BIT(7) | BIT(2))) {
+ if (status & BIT(2))
+ linkstat = USB_LINK_ID;
+ else
+ linkstat = USB_LINK_VBUS;
+ } else
linkstat = USB_LINK_NONE;
dev_dbg(twl->dev, "HW_CONDITIONS 0x%02x/%d; link %d\n",