Re: [PATCH v2 4/4] usb: dwc3: Workaround for super-speed host on dra7 in dual-role mode

From: Vivek Gautam
Date: Thu Feb 23 2017 - 22:14:51 EST

On 02/24/2017 06:27 AM, Peter Chen wrote:
On Thu, Feb 23, 2017 at 02:04:50PM +0530, Vivek Gautam wrote:

On 02/16/2017 06:36 PM, Roger Quadros wrote:
dra7 OTG core limits the host controller to USB2.0 (high-speed) mode
when we're operating in dual-role.

We work around that by bypassing the OTG core and reading the
extcon framework directly for ID/VBUS events.

Signed-off-by: Roger Quadros <rogerq@xxxxxx>
Documentation/devicetree/bindings/usb/dwc3.txt | 2 +
drivers/usb/dwc3/core.c | 169 ++++++++++++++++++++++++-
drivers/usb/dwc3/core.h | 5 +
3 files changed, 170 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt
index e3e6983..9955c0d 100644
--- a/Documentation/devicetree/bindings/usb/dwc3.txt
+++ b/Documentation/devicetree/bindings/usb/dwc3.txt
@@ -53,6 +53,8 @@ Optional properties:
- snps,quirk-frame-length-adjustment: Value for GFLADJ_30MHZ field of GFLADJ
register for post-silicon frame length adjustment when the
fladj_30mhz_sdbnd signal is invalid or incorrect.
+ - extcon: phandle to the USB connector extcon device. If present, extcon
+ device will be used to get USB cable events instead of OTG controller.
- <DEPRECATED> tx-fifo-resize: determines if the FIFO *has* to be reallocated.
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 619fa7c..b02d911 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c

@@ -1587,6 +1727,14 @@ static int dwc3_probe(struct platform_device *pdev)
+ if (dev->of_node) {
+ if (of_property_read_bool(dev->of_node, "extcon"))
+ dwc->edev = extcon_get_edev_by_phandle(dev, 0);
Don't we want separate edev's for vbus and id ?
One can have separate pins connected to them and in that case
we can't get the events out of one pin only.

Current extcon-usb-gpio driver supports id and vbus at the same time,
that means there are two optional gpios under one extcon node.

Right, and we would want to leverage that by providing couple
of phandles for vbus and id, and requesting the two in driver.


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