linux-kernel - Re: [PATCH v3] extcon: add Maxim MAX3355 driver

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Message-ID: <56732719.7020301@cogentembedded.com>
Date:	Fri, 18 Dec 2015 00:20:25 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Chanwoo Choi <cw00.choi@...sung.com>, robh+dt@...nel.org,
	pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	myungjoo.ham@...sung.com, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc:	linux-sh@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH v3] extcon: add Maxim MAX3355 driver

Hello.

On 12/17/2015 05:34 AM, Chanwoo Choi wrote:

>> On 2015년 12월 17일 03:07, Sergei Shtylyov wrote:
>>> Maxim Integrated MAX3355E chip integrates a charge pump and comparators to
>>> enable a system with an integrated USB OTG dual-role transceiver to
>>> function as an USB OTG dual-role device. In addition to sensing/controlling
>>> Vbus, the chip also passes thru the ID signal from the USB OTG connector.
>>> On some Renesas boards, this signal is just fed into the SoC thru a GPIO
>>> pin -- there's no real OTG controller, only host and gadget USB controllers
>>> sharing the same USB bus; however, we'd like to allow host or gadget
>>> drivers to be loaded depending on the cable type, hence the need for the
>>> MAX3355 extcon driver. The Vbus status signals are also wired to GPIOs
>>> (however, we aren't currently interested in them), the OFFVBUS# signal is
>>> controlled by the host controllers, there's also the SHDN# signal wired to
>>> a GPIO, it should be driven high for the normal operation.
>>>
>>> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
>>>
>>> ---
>>> Changes in version 3:
>>> - reformatted the change log.
>>>
>>> Changes in version 2:
>>> - added the USB gadget cable support;
>>> - added the remove() driver method which drives SHDN# GPIO low to save power;
>>> - dropped vendor prefix from the ID GPIO property name;
>>> - changed the GPIO property name suffix to "-gpios";
>>> - switched to usign extcon_set_cable_state_() API;
>>> - switched to using the gpiod/sleeping 'gpiolib' APIs;
>>> - addded error messages to max3355_probe();
>>> - added IRQF_NO_SUSPEND flasg to the devm_request_threaded_irq() call;
>>> - renamed 'ret' variable to 'err' in max3355_probe();
>>> - expanded the Kconfig entry help text;
>>> - added vendor name to the patch summary, the bindings document, the Kconfig
>>>    entry, the driver heading comment, the module description, and the change log;
>>> - fixed up and reformatted the change log.
>>>
>>>   Documentation/devicetree/bindings/extcon/extcon-max3355.txt |   21 +
>>>   drivers/extcon/Kconfig                                      |    8
>>>   drivers/extcon/Makefile                                     |    1
>>>   drivers/extcon/extcon-max3355.c                             |  153 ++++++++++++
>>>   4 files changed, 183 insertions(+)
>>>
>
> [snip]
>
>>> +	return 0;
>>> +}
>>> +
>>> +static int max3355_remove(struct platform_device *pdev)
>>> +{
>>> +	struct max3355_data *data = platform_get_drvdata(pdev);
>>> +
>>> +	gpiod_set_value_cansleep(data->shdn_gpiod, 0);
>
> Don't need to handle the 'shdn' gpio on resume/suspend funtcion?
>
> But, if the interrput of id gpio is used for wakeup source,
> there is no reason to handle it for suspend mode.

    You told me to pass IRQF_NO_SUSPEND to devm_request_threaded_irq(), didn't 
you?

> [snip]

> Thanks,
> Chanwoo Choi

MBR, Sergei

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