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Message-ID: <54C66B0D.9040109@ti.com>
Date: Mon, 26 Jan 2015 18:27:57 +0200
From: Roger Quadros <rogerq@...com>
To: <cw00.choi@...sung.com>
CC: Felipe Balbi <balbi@...com>, <tony@...mide.com>,
"myungjoo.ham@...sung.com" <myungjoo.ham@...sung.com>,
<george.cherian@...com>, <nsekhar@...com>,
devicetree <devicetree@...r.kernel.org>,
<linux-usb@...r.kernel.org>, <linux-omap@...r.kernel.org>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/7] extcon: usb-gpio: Introduce gpio usb extcon driver
Hi Chanwoo,
All your comments are valid. Need some clarification on one comment.
On 26/01/15 15:56, Chanwoo Choi wrote:
> Hi Roger,
>
> This patch looks good to me. But I add some comment.
> If you modify some comment, I'll apply this patch on 3.21 queue.
>
> On Mon, Jan 26, 2015 at 9:15 PM, Roger Quadros <rogerq@...com> wrote:
>> This driver observes the USB ID pin connected over a GPIO and
>> updates the USB cable extcon states accordingly.
>>
>> The existing GPIO extcon driver is not suitable for this purpose
>> as it needs to be taught to understand USB cable states and it
>> can't handle more than one cable per instance.
>>
>> For the USB case we need to handle 2 cable states.
>> 1) USB (attach/detach)
>> 2) USB-Host (attach/detach)
>>
>> This driver can be easily updated in the future to handle VBUS
>> events in case it happens to be available on GPIO for any platform.
>>
>> Signed-off-by: Roger Quadros <rogerq@...com>
>> ---
>> .../devicetree/bindings/extcon/extcon-usb-gpio.txt | 20 ++
>> drivers/extcon/Kconfig | 7 +
>> drivers/extcon/Makefile | 1 +
>> drivers/extcon/extcon-usb-gpio.c | 214 +++++++++++++++++++++
>> 4 files changed, 242 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
>> create mode 100644 drivers/extcon/extcon-usb-gpio.c
>>
<snip>
>> +
>> +static int usb_extcon_probe(struct platform_device *pdev)
>> +{
>> + struct device *dev = &pdev->dev;
>> + struct device_node *np = dev->of_node;
>> + struct usb_extcon_info *info;
>> + int ret;
>> +
>> + if (!np)
>> + return -EINVAL;
>> +
>> + info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
>> + if (!info)
>> + return -ENOMEM;
>> +
>> + info->dev = dev;
>> + info->id_gpiod = devm_gpiod_get(&pdev->dev, "id");
>> + if (IS_ERR(info->id_gpiod)) {
>> + dev_err(dev, "failed to get ID GPIO\n");
>> + return PTR_ERR(info->id_gpiod);
>> + }
>> +
>> + ret = gpiod_set_debounce(info->id_gpiod,
>> + USB_GPIO_DEBOUNCE_MS * 1000);
>> + if (ret < 0)
>> + info->debounce_jiffies = msecs_to_jiffies(USB_GPIO_DEBOUNCE_MS);
>> +
>> + INIT_DELAYED_WORK(&info->wq_detcable, usb_extcon_detect_cable);
>> +
>> + info->id_irq = gpiod_to_irq(info->id_gpiod);
>> + if (info->id_irq < 0) {
>> + dev_err(dev, "failed to get ID IRQ\n");
>> + return info->id_irq;
>> + }
>> +
>> + ret = devm_request_threaded_irq(dev, info->id_irq, NULL,
>> + usb_irq_handler,
>> + IRQF_SHARED | IRQF_ONESHOT |
>> + IRQF_NO_SUSPEND,
>> + pdev->name, info);
use of IRQF_NO_SUSPEND is not recommended to be used together with IRQF_SHARED so
I'll remove IRQF_SHARED from here if we decide to stick with IRQF_NO_SUSPEND.
More on this below.
>> + if (ret < 0) {
>> + dev_err(dev, "failed to request handler for ID IRQ\n");
>> + return ret;
>> + }
>> +
>> + info->edev = devm_extcon_dev_allocate(dev, usb_extcon_cable);
>> + if (IS_ERR(info->edev)) {
>> + dev_err(dev, "failed to allocate extcon device\n");
>> + return -ENOMEM;
>> + }
>> +
>> + ret = devm_extcon_dev_register(dev, info->edev);
>> + if (ret < 0) {
>> + dev_err(dev, "failed to register extcon device\n");
>> + return ret;
>> + }
>> +
>> + platform_set_drvdata(pdev, info);
>
> I prefer to execute the device_init_wakeup() function as following
> for suspend/resume function:
> device_init_wakeup(&pdev->dev, 1);
>
>> +
>> + /* Perform initial detection */
>> + usb_extcon_detect_cable(&info->wq_detcable.work);
>> +
>> + return 0;
>> +}
>> +
>> +static int usb_extcon_remove(struct platform_device *pdev)
>> +{
>> + struct usb_extcon_info *info = platform_get_drvdata(pdev);
>> +
>> + cancel_delayed_work_sync(&info->wq_detcable);
>
> Need to add blank line.
>
>> + return 0;
>> +}
>> +
>> +#ifdef CONFIG_PM_SLEEP
>> +static int usb_extcon_suspend(struct device *dev)
>> +{
>> + struct usb_extcon_info *info = dev_get_drvdata(dev);
>> +
>> + enable_irq_wake(info->id_irq);
>
> I prefer to use device_may_wakeup() function for whether
> executing enable_irq_wake() or not. Also, The disable_irq()
> in the suspend function would prevent us from discarding interrupt
> before wakeup from suspend completely.
>
I need more clarification here.
If we are going to use enable_irq_wake() here then what is the point of IRQF_NO_SUSPEND?
>From Documentation/power/suspend-and-interrupts.txt I see that interrupts marked
as IRQF_NO_SUSPEND should not be configured for system wakeup using enable_irq_wake().
what is your preference?
Is it good enough to not use IRQF_NO_SUSPEND but use enable_irq_wake() instead to
enable system wakeup for that IRQ.
> if (device_may_wakeup(dev))
> enable_irq_wake(info->id_irq);
> disable_irq(info->id_irq);
why do we need to disable irq here? How will the system wakeup if IRQ is disabled?
>
>
>> + return 0;
>> +}
>> +
<snip>
cheers,
-roger
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