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From: Vivek Gautam Date: Tue, 28 Feb 2017 19:24:15 +0530 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 4/4] usb: dwc3: Workaround for super-speed host on dra7 in dual-role mode To: cwchoi00@gmail.com Cc: Roger Quadros , Felipe Balbi , Chanwoo Choi , Linux USB Mailing List , linux-kernel Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Feb 25, 2017 at 9:20 AM, Chanwoo Choi wrote: > 2017-02-25 12:46 GMT+09:00 Chanwoo Choi : >> Hi, >> >> 2017-02-24 21:02 GMT+09:00 Roger Quadros : >>> +Chanwoo >>> >>> Hi Vivek, >>> >>> On 23/02/17 10:34, 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 >>>>> --- >>>>> 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. >>>>> - 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 >>>> >>>> [snip] >>>> >>>>> @@ -1587,6 +1727,14 @@ static int dwc3_probe(struct platform_device *pdev) >>>>> dwc3_get_properties(dwc); >>>>> + 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. >>> >>> Is such kind of hardware really there? Ideally one extcon device >>> represents one connector. So VBUS and ID events of a single USB >>> port should come on one extcon device. >>> If it doesn't then you need to fix your platforms extcon driver >>> so that it does. Right, i see it now. One edev for one connector. >>> Chanwoo can correct me if I'm wrong on this understanding. >>> >>> Currently, if VBUS and ID come on GPIOs the extcon-usb-gpio driver >>> takes care of both. >> >> Basically, one extcon device driver can support the multiple >> external connectors if the detection h/w or port is same. >> >> One extcon device with extcon-usb-gpio.c can support the detection >> of both ID and VBUS. >> >> But, if there is any issue of h/w schematic, we need to consider >> how to use the extcon device. > > Additionally, the extcon-usb-gpio.c use the two gpio pins > to detect both ID and VBUS pins. We can check it on documentation[1] > of extcon-usb-gpio driver. > > [1] https://git.kernel.org/cgit/linux/kernel/git/chanwoo/extcon.git/tree/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt Thanks Chanwoo, i understand it now. The extcon-usb-gpio supports both vbus and id gpio, and updates the state of the edev likewise. > > -- > Best Regards, > Chanwoo Choi > Samsung Electronics > -- > To unsubscribe from this list: send the line "unsubscribe linux-usb" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html regards Vivek -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project