linux-kernel - Re: [PATCH v4] extcon: add Maxim MAX3355 driver

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Date:	Fri, 18 Dec 2015 17:33:30 +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 v4] extcon: add Maxim MAX3355 driver

Hello.

On 12/18/2015 4:14 AM, Chanwoo Choi wrote:

> Except for just one comment below, Looks good to me.
> Acked-by: Chanwoo Choi <cw00.choi@...sung.com>

> I'll wait for a few days to get the review from DT maintainer
> before applying it on extcon-next branch.

> On 2015년 12월 18일 07:47, 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>
>>
>> ---
>> The patch is against the 'extcon-next' branch of the 'extcon.git' repo.
>>
>> Changes in version 4:
>> - stopped calling kstrdup() for the device name;
>> - removed unneeded 'owner' field initializer;
>> - moved devm_extcon_allocate() call further down in the probe() method;
>> - extended the driver copyright;
>> - indented the continuation lines in the binding document.
>>
>> 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                             |  151 ++++++++++++
>>   4 files changed, 181 insertions(+)
>>
>> Index: extcon/Documentation/devicetree/bindings/extcon/extcon-max3355.txt
>> ===================================================================
>> --- /dev/null
>> +++ extcon/Documentation/devicetree/bindings/extcon/extcon-max3355.txt
>> @@ -0,0 +1,21 @@
>> +Maxim Integrated MAX3355 USB OTG chip
>> +-------------------------------------
>> +
>> +MAX3355 integrates a charge pump and comparators to enable a system with an
>> +integrated USB OTG dual-role transceiver to function as a USB OTG dual-role
>> +device.
>> +
>> +Required properties:
>> +- compatible: should be "maxim,max3355";
>> +- maxim,shdn-gpios: should contain a phandle and GPIO specifier for the GPIO pin
>> +		    connected to the MAX3355's SHDN# pin;
>> +- id-gpios: should contain a phandle and GPIO specifier for the GPIO pin
>> +	    connected to the MAX3355's ID_OUT pin.
>> +
>> +Example (Koelsch board):
>
> You mean that "koelsch" board might be arch/arm/boot/dts/r8a7791-koelsch.dts.
> But, the max3355 dt node isn't really included in r8a7791-koelsch.dts.

    Of course, I couldn't post the device tree patch before the binding was 
accepted.

> I recommend that you add the accurate information because the wrong
> info causes the confusion. So, I'd like you to change it as following:
>
> 	"Example (Koelsch board):" -> "Example:"
>
> After adding the max3355 dt node to Koelsch board on separate patch,
> you modify this documentation for real usage case of max3355 dt node.

    No dire need to modify the documentation then. Should I still repost?

[...]

> Thanks,
> Chanwoo Choi

MBR, Sergei

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