From: Jack Pham <jackp@xxxxxxxxxxxxxx> The default value for the 'transceiver select' field of the PORTSC register may not always be correct. Previously the phy-msm-usb driver would do this for us, but since ehci-msm can now be instantiated standalone without any PHY driver, the register needs to be explicitly initialized to ULPI mode to properly communicate with the PHY. This is not readily apparent, as firmware or bootloader code also happen to pre-initialize this for us. However, it can manifest when performing a driver unbind/rebind as follows: cd /sys/bus/platform/drivers/msm_hsusb_host echo QCOM8040:00 > unbind echo QCOM8040:00 > bind The EHCI core executes a controller reset as part of this, and as a result the register in question would revert to its default state and must be re-initialized properly. Furthermore this may be useful in the future when adding PM suspend/resume support. Signed-off-by: Jack Pham <jackp@xxxxxxxxxxxxxx> Signed-off-by: Timur Tabi <timur@xxxxxxxxxxxxxx> --- drivers/usb/host/ehci-msm.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/usb/host/ehci-msm.c b/drivers/usb/host/ehci-msm.c index 102837e..b71947d 100644 --- a/drivers/usb/host/ehci-msm.c +++ b/drivers/usb/host/ehci-msm.c @@ -56,6 +56,8 @@ static int ehci_msm_reset(struct usb_hcd *hcd) if (retval) return retval; + /* select ULPI phy and clear other status/control bits in PORTSC */ + writel(PORTSC_PTS_ULPI, USB_PORTSC); /* bursts of unspecified length. */ writel(0, USB_AHBBURST); /* Use the AHB transactor, allow posted data writes */ -- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project. -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
