On Thu, Jan 19, 2017 at 02:33:49PM +0800, Peter Chen wrote: > On Wed, Dec 28, 2016 at 02:56:49PM -0800, Stephen Boyd 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> > > Acked-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx> > > Cc: <devicetree@xxxxxxxxxxxxxxx> > > Acked-by: Rob Herring <robh@xxxxxxxxxx> > > Signed-off-by: Stephen Boyd <stephen.boyd@xxxxxxxxxx> > > Greg, is it ok I pick up this patch, and send it with chipidea > changes together for 4.11-rc1 later? No objection from me. thanks, greg k-h -- 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
