On Wed, Sep 7, 2016 at 4:35 PM, Stephen Boyd <stephen.boyd@xxxxxxxxxx> wrote: > The qcom HSIC ULPI phy doesn't have any bits set in the vendor or > product ID registers. This makes it impossible to make a ULPI > driver match against the ID registers. Add support to discover > the ULPI phys via DT help alleviate this problem. In the DT case, > we'll look for a ULPI bus node underneath the device registering > the ULPI viewport (or the parent of that device to support > chipidea's device layout) and then match up the phy node > underneath that with the ULPI device that's created. > > The side benefit of this is that we can use standard properties > in the phy node like clks, regulators, gpios, etc. because we > don't have firmware like ACPI to turn these things on for us. And > we can use the DT phy binding to point our phy consumer to the > phy provider. > > The ULPI bus code supports native enumeration by reading the > vendor ID and product ID registers at device creation time, but > we can't be certain that those register reads will succeed if the > phy is not powered up. To avoid any problems with reading the ID > registers before the phy is powered we fallback to DT matching > when the ID reads fail. > > If the ULPI spec had some generic power sequencing for these > registers we could put that into the ULPI bus layer and power up > the device before reading the ID registers. Unfortunately this > doesn't exist and the power sequence is usually device specific. > By having the device matched up with DT we can avoid this > problem. > > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Cc: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx> > Cc: <devicetree@xxxxxxxxxxxxxxx> > Cc: Rob Herring <robh+dt@xxxxxxxxxx> > Signed-off-by: Stephen Boyd <stephen.boyd@xxxxxxxxxx> > --- > Documentation/devicetree/bindings/usb/ulpi.txt | 20 +++++++ > drivers/usb/common/ulpi.c | 77 ++++++++++++++++++++++++-- > 2 files changed, 92 insertions(+), 5 deletions(-) > create mode 100644 Documentation/devicetree/bindings/usb/ulpi.txt Acked-by: Rob Herring <robh@xxxxxxxxxx> But one concern below. > -static int ulpi_register(struct device *dev, struct ulpi *ulpi) > +static int ulpi_of_register(struct ulpi *ulpi) > +{ > + struct device_node *np = NULL, *child; > + > + /* Find a ulpi bus underneath the parent or the parent of the parent */ parent of the parent is called the grandparent. > + if (ulpi->dev.parent->of_node) > + np = of_find_node_by_name(ulpi->dev.parent->of_node, "ulpi"); > + else if (ulpi->dev.parent->parent && ulpi->dev.parent->parent->of_node) > + np = of_find_node_by_name(ulpi->dev.parent->parent->of_node, First setting "parent = ulpi->dev.parent" would make this a bit easier on the eyes. When is it valid to be the grandparent? The binding doesn't mention that. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html