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Message-id: <5626FF05.80908@samsung.com>
Date: Wed, 21 Oct 2015 11:57:09 +0900
From: Chanwoo Choi <cw00.choi@...sung.com>
To: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
Cc: robh+dt@...nel.org, pawel.moll@....com, mark.rutland@....com,
ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
myungjoo.ham@...sung.com, grant.likely@...aro.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-sh@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH] extcon: add MAX3355 driver
Hi Sergei,
I think this patch is too much delay. I recommend you better to develop
this driver based on latest extcon-next branch[1].
[1] https://git.kernel.org/cgit/linux/kernel/git/chanwoo/extcon.git/log/?h=extcon-next
Thanks,
Chanwoo Choi
On 2015년 10월 21일 03:20, Sergei Shtylyov wrote:
> Hello.
>
> On 12/18/2014 12:58 AM, Sergei Shtylyov wrote:
>
>>>> MAX3355E chip 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. 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're not currently intested in them), the OFFVBUS# signal
>>>> is controlled by the host controllers, there's also the SHDN# signal wired to
>>>> GPIO, which should be high for normal operation.
>>
>>>> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
>>
>>>> ---
>>>> The patch is against the 'extcon-next' branch of the 'extcon.git' repo.
>>
>>>> Documentation/devicetree/bindings/extcon/extcon-max3355.txt | 21 ++
>>>> drivers/extcon/Kconfig | 6
>>>> drivers/extcon/Makefile | 1
>>>> drivers/extcon/extcon-max3355.c | 122
>>>> ++++++++++++
>>>> 4 files changed, 150 insertions(+)
>>
>>>> Index: extcon/Documentation/devicetree/bindings/extcon/extcon-max3355.txt
>>>> ===================================================================
>>>> --- /dev/null
>>>> +++ extcon/Documentation/devicetree/bindings/extcon/extcon-max3355.txt
>>>> @@ -0,0 +1,21 @@
>>>> +MAX3355 USB OTG chip
>>
>>> Need manufactor information as following :
>>> -> Maxim MAX3355
>>
>> Would be Maxim enough? Or perhaps I should use Maxim Integrated [Products]?
>
> You haven't replied to my questions.
>
>>>> +--------------------
>>>> +
>>>> +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-gpio: should contain a phandle and GPIO specifier for the
>>>> GPIO pin
>>>> + connected to the MAX3355's SHDN# pin;
>>>> +- maxim,id-gpio: should contain a phandle and GPIO specifier for the GPIO pin
>>>> + connected to the MAX3355's ID_OUT pin.
>>>> +
>>>> +Example (Koelsch board):
>>>> +
>>>> + usb-otg {
>>>> + compatible = "maxim,max3355";
>>>> + maxim,shdn-gpio = <&gpio2 4 GPIO_ACTIVE_LOW>;
>>>> + maxim,id-gpio = <&gpio5 31 GPIO_ACTIVE_HIGH>;
>>
>>> Kernel already supported the gpio helper function to get gpio from devicetree.
>>> I prefer use follwoing style by using of_get_gpio()/of_get_gpio_flags() in
>>> include/linux/of_gpio.h.
>>
>>> gpios = <&gpio2 4 GPIO_ACTIVE_LOW>, <&gpio5 31 GPIO_ACTIVE_HIGH>;
>>
>> OK, though Documentation/devicetree/bindings/gpio/gpio.txt does not seem
>> to insist on using this one...
>
> Moreover, it now says "gpios" isn't allowed for the new bindings. So I have to strongly disagree here...
>
> [...]
>
>>>> +static irqreturn_t max3355_id_irq(int irq, void *dev_id)
>>>> +{
>>>> + struct max3355_data *data = dev_id;
>>>> + int id = gpio_get_value(data->id_gpio);
>>>> +
>>>> + extcon_set_cable_state(data->edev, "USB-HOST", !id);
>>
>>> You have to get the gpio flag in the devicetree by using of_get_gpio_flags()
>>> function
>>> and then you would set the cable state according to gpio state and flag.
>>
>> I'm sorry but I just don't see why I have to do it. This is not a generic
>> GPIO driver, and the polarities of the GPIOs are determined solely by the
>> MAX3355 specs.
>
> Again, got not reply...
>
>> [...]
>>>> +static int max3355_probe(struct platform_device *pdev)
>>>> +{
>>>> + struct device_node *np = pdev->dev.of_node;
>>>> + struct max3355_data *data;
>>>> + int gpio, irq, ret;
>>>> +
>>>> + data = devm_kzalloc(&pdev->dev, sizeof(struct max3355_data),
>>>> + GFP_KERNEL);
>>>> + if (!data)
>>>> + return -ENOMEM;
>>>> +
>>>> + data->edev = devm_extcon_dev_allocate(&pdev->dev, max3355_cable);
>>>> + if (IS_ERR(data->edev)) {
>>>> + dev_err(&pdev->dev, "failed to allocate extcon device\n");
>>>> + return PTR_ERR(data->edev);
>>>> + }
>>>> + data->edev->name = kstrdup(np->name, GFP_KERNEL);
>>>> +
>>>> + gpio = of_get_named_gpio(np, "maxim,id-gpio", 0);
>>
>>> Use of_get_gpio() or of_get_gpio_flags().
>>
>> OK, I'll use the first one.
>
> No, I won't due to not being able to use "gpios" anymore.
>
> [...]
>
>>>> +
>>>> + ret = devm_request_threaded_irq(&pdev->dev, irq, NULL, max3355_id_irq,
>>>> + IRQF_TRIGGER_RISING |
>>>> + IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
>>
>>> Is it right to add both RISING and FALLING trigger?
>>
>> How else I'm supposed to know when the OTG ID signal goes low and high?
>>
>>> and need to add IRQF_NO_SUSPEND to wakeup from suspend state when interrupt
>>> happen.
>>
>> Hm, are you sure we want to wake up on plugging another kind of USB cable?
>
> No reply to that as well...
>
> [...]
>>>> +static struct platform_driver max3355_driver = {
>>>> + .probe = max3355_probe,
>>>> + .driver = {
>>>> + .name = "extcon-max3355",
>>>> + .of_match_table = max3355_match_table,
>>>> + .owner = THIS_MODULE,
>>>> + },
>>>> +};
>>>> +
>>>> +module_platform_driver(max3355_driver);
>>>> +
>>
>>> Don't need un-used blank line.
>>
>> I don't understand. There's empty line in such case in extcon-gpio.c...
>
> No reply...
>
> [...]
>
>>> Thanks,
>>> Chanwoo Choi
>
> MBR, Sergei
>
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