linux-kernel - Re: [PATCH v2 2/3] usb: dwc3: Add Qualcomm DWC3 glue driver

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Message-ID: <20180413173322.GA30306@usblab-sd-06.qualcomm.com>
Date:   Fri, 13 Apr 2018 10:33:22 -0700
From:   Jack Pham <jackp@...eaurora.org>
To:     Manu Gautam <mgautam@...eaurora.org>
Cc:     balbi@...nel.org, robh@...nel.org, andy.gross@...aro.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, robh+dt@...nel.org,
        linux-arm-msm@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v2 2/3] usb: dwc3: Add Qualcomm DWC3 glue driver

Hi Manu,

On Fri, Apr 13, 2018 at 10:21:23PM +0530, Manu Gautam wrote:
> DWC3 controller on Qualcomm SOCs has a Qscratch wrapper.
> Some of its uses are described below resulting in need to
> have a separate glue driver instead of using dwc3-of-simple:
>  - It exposes register interface to override vbus-override
>    and lane0-pwr-present signals going to hardware. These
>    must be updated in peripheral mode for DWC3 if vbus lines
>    are not connected to hardware block. Otherwise RX termination
>    in SS mode or DP pull-up is not applied by device controller.
>  - pwr_events_irq_stat support to check if USB2 PHY is in L2 state
>    before glue driver proceeds with suspend.
>  - Support for wakeup interrupts lines that are asserted whenever
>    there is any wakeup event on USB3 or USB2 bus.
>  - Support to replace pip3 clock going to DWC3 with utmi clock
>    for hardware configuration where SSPHY is not used with DWC3.
> 
> Signed-off-by: Manu Gautam <mgautam@...eaurora.org>

<snip>

> +static int dwc3_qcom_register_extcon(struct dwc3_qcom *qcom)
> +{
> +	struct device		*dev = qcom->dev;
> +	struct extcon_dev	*host_edev;
> +	int			ret;
> +
> +	if (!of_property_read_bool(dev->of_node, "extcon"))
> +		return 0;
> +
> +	qcom->edev = extcon_get_edev_by_phandle(dev, 0);

Are the extcon phandles bound to the glue node? I don't see the
description in the bindings doc in PATCH 1/3. And if so, would it be
a duplicate of the child node's extcon binding? Then again, the
alternative would be to grab it directly from the child (i.e.
qcom->dwc3->dev.of_node) which I'm not sure is ok to do or not.

Jack
-- 
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