patch "usb: ulpi: Support device discovery via DT" added to usb-testing

This is a note to let you know that I've just added the patch titled

usb: ulpi: Support device discovery via DT

to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-testing branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will be merged to the usb-next branch sometime soon, after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.

From: Stephen Boyd <[email protected]>
Date: Wed, 28 Dec 2016 14:56:49 -0800
Subject: usb: ulpi: Support device discovery via DT

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.

---
 Documentation/devicetree/bindings/usb/ulpi.txt | 20 +++++++
 drivers/usb/common/ulpi.c                      | 79 ++++++++++++++++++++++++--
 2 files changed, 93 insertions(+), 6 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/usb/ulpi.txt

new file mode 100644
index 000000000000..ca179dc4bd50
@@ -0,0 +1,20 @@
+ULPI bus binding
+----------------
+
+Phys that are behind a ULPI connection can be described with the following
+binding. The host controller shall have a "ulpi" named node as a child, and
+that node shall have one enabled node underneath it representing the ulpi
+device on the bus.
+
+EXAMPLE
+-------
+
+usb {
+	compatible = "vendor,usb-controller";
+
+	ulpi {
+		phy {
+			compatible = "vendor,phy";
+		};
+	};
+};

2.11.1


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