From: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/usb/otg/twl4030-usb.c | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
--- 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_linksta
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",
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
