On Thu, Dec 10, 2015 at 06:28:56PM -0600, Timur Tabi wrote: > From: Jack Pham <ja...@codeaurora.org> > > 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 <ja...@codeaurora.org> > Signed-off-by: Timur Tabi <ti...@codeaurora.org>
Reviewed-by: Andy Gross <andy.gr...@linaro.org> -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
