Re: [PATCH 0/8] usb: dwc3: add dual-role support

Roger Quadros
2017-02-09T07:53:13Z

Vivek,

On 09/02/17 08:42, Vivek Gautam wrote:
> Hi Roger,
>
> On Mon, Jan 23, 2017 at 4:49 PM, Roger Quadros <rogerq@ti.com> wrote:
>> Hi,
>>
>> 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.

cheers,
-roger
>
>
> Regards
> Vivek
>
>> 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?).
>>
>> cheers,
>> -roger
>>
>> 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(-)
>>
>> --
>> 2.7.4
>>
>

--
cheers,
-roger