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USB: twl4030-usb: fix minor reporting goofage

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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>
This commit is contained in:
David Brownell 2009-03-31 12:26:10 -07:00 committed by Greg Kroah-Hartman
parent dc2f2b7505
commit def6f8b978
1 changed files with 19 additions and 7 deletions
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26
drivers/usb/otg/twl4030-usb.c
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@ -217,6 +217,7 @@
/* In module TWL4030_MODULE_PM_MASTER */ /* In module TWL4030_MODULE_PM_MASTER */
#define PROTECT_KEY 0x0E #define PROTECT_KEY 0x0E
#define STS_HW_CONDITIONS 0x0F
/* In module TWL4030_MODULE_PM_RECEIVER */ /* In module TWL4030_MODULE_PM_RECEIVER */
#define VUSB_DEDICATED1 0x7D #define VUSB_DEDICATED1 0x7D
@ -351,15 +352,26 @@ static enum linkstat twl4030_usb_linkstat(struct twl4030_usb *twl)
int status; int status;
int linkstat = USB_LINK_UNKNOWN; 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) if (status < 0)
dev_err(twl->dev, "USB link status err %d\n", status); dev_err(twl->dev, "USB link status err %d\n", status);
else if (status & BIT(7)) else if (status & (BIT(7) | BIT(2))) {
linkstat = USB_LINK_VBUS; if (status & BIT(2))
else if (status & BIT(2)) linkstat = USB_LINK_ID;
linkstat = USB_LINK_ID; else
else linkstat = USB_LINK_VBUS;
} else
linkstat = USB_LINK_NONE; linkstat = USB_LINK_NONE;
dev_dbg(twl->dev, "HW_CONDITIONS 0x%02x/%d; link %d\n", dev_dbg(twl->dev, "HW_CONDITIONS 0x%02x/%d; link %d\n",