Re: [PATCH 0/8] usb: dwc3: add dual-role support
From: Vivek Gautam
Date: Thu Feb 09 2017 - 06:50:53 EST
On Thu, Feb 9, 2017 at 1:19 PM, Roger Quadros <rogerq@xxxxxx> wrote:
> On 09/02/17 08:42, Vivek Gautam wrote:
>> Hi Roger,
>> On Mon, Jan 23, 2017 at 4:49 PM, Roger Quadros <rogerq@xxxxxx> wrote:
>>> We rely on the OTG controller block to provide us with
>>> VBUS and ID line status via an interrupt.
>>> This is then used to switch the controller between host, peripheral
>>> and idle roles based on the following table.
>>> ID VBUS dual-role state
>>> -- ---- ---------------
>>> 0 x A_HOST - Host controller active
>>> 1 0 B_IDLE - Both Host and Gadget controllers inactive
>>> 1 1 B_PERIPHERAL - Gadget controller active
>> Thanks for this series.
>> Sorry, i was held up with something else so couldn't take a look at it.
>> I will integrate this with my work, and add some basic extcon
>> support to enable passing vbus and id events to dwc3 layer to test
>> this out on msm platforms.
> I already have this done for one of our platforms to workaround
> a limitation with the OTG IP block on it.
> I can post it today and you can give your comments.
Okay, cool. Thanks. I will wait.
>>> Couple of things to clarify:
>>> - There is a small window where we can potentially miss an
>>> event related to OTG. I've added a comment in the code where this
>>> could happen. How can we prevent this? Is it better to just leave
>>> the OTG events unmasked (but keep otg_irq on ARM GIC disabled)
>>> so that any new events can be captured by the OTG event register
>>> and interrupt re-triggered if it has not been serviced by the
>>> previous interrupt.
>>> - I'm running the entire dual-role state change logic inside
>>> the threaded interrupt handler with dwc->lock (spinlock) held
>>> but IRQs enabled. OTG events are very rare i.e. manual intervention
>>> so I don't see this as a problem. Just wanted to double check.
>>> - Some SoC's (e.g. Qualcomm MSM) do not have the OTG controller block
>>> but do have both host and peripheral controllers and so can operate
>>> in dual role mode. Current series does not address this case.
>>> We can get dual-role to work with such SoCs if core.c can get
>>> information about ID and VBUS somehow (private interface
>>> from parent or directly read extcon?).
>>> Roger Quadros (8):
>>> usb: otg-fsm: Prevent build warning "VDBG" redefined
>>> usb: dwc3-omap: Fix missing break in dwc3_omap_set_mailbox()
>>> usb: dwc3: use BIT() macro where possible
>>> usb: dwc3: core.h: add some register definitions
>>> usb: dwc3: add dual-role support
>>> ARM: dts: dra7x-evm: Enable dual-role mode for USB1
>>> ARM: dts: am43xx: Enable dual-role mode for USB1
>>> ARM: dts: am57xx-idk: Enable dual-role mode for USB2
>>> arch/arm/boot/dts/am437x-gp-evm.dts | 2 +-
>>> arch/arm/boot/dts/am437x-sk-evm.dts | 2 +-
>>> arch/arm/boot/dts/am43x-epos-evm.dts | 2 +-
>>> arch/arm/boot/dts/am57xx-idk-common.dtsi | 2 +-
>>> arch/arm/boot/dts/dra7-evm.dts | 2 +-
>>> arch/arm/boot/dts/dra72-evm-common.dtsi | 2 +-
>>> drivers/usb/common/usb-otg-fsm.c | 7 +
>>> drivers/usb/dwc3/core.c | 583 ++++++++++++++++++++++++++++++-
>>> drivers/usb/dwc3/core.h | 312 ++++++++++++-----
>>> drivers/usb/dwc3/dwc3-omap.c | 49 +--
>>> drivers/usb/dwc3/gadget.c | 18 +-
>>> drivers/usb/dwc3/gadget.h | 20 +-
>>> drivers/usb/phy/phy-fsl-usb.c | 7 +
>>> include/linux/usb/otg-fsm.h | 15 -
>>> 14 files changed, 848 insertions(+), 175 deletions(-)
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project