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Date: Fri, 30 Jan 2015 09:06:07 +0900
From: Chanwoo Choi <cw00.choi@...sung.com>
To: Roger Quadros <rogerq@...com>
Cc: myungjoo.ham@...sung.com, balbi@...com, tony@...mide.com,
george.cherian@...com, nsekhar@...com, devicetree@...r.kernel.org,
linux-usb@...r.kernel.org, linux-omap@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/7] extcon: usb-gpio: Introduce gpio usb extcon driver
Hi Roger,
On 01/29/2015 08:26 PM, Roger Quadros wrote:
> Chanwoo,
>
> On 29/01/15 03:49, Chanwoo Choi wrote:
>> Hi Roger,
>>
>> We need to discuss one point about 'id_irqwake'.
>> I don't recommend to use 'id_irqwake' field.
>>
>> And I catch build warning by using "select" keywork in Kconfig.
>> It is my wrong guide of "select" keyword. So, I'll change it
>> as 'depends on' keyword.
>>
>> Looks good to me except for 'id_irqwake'.
>> I'll apply this patch on 3.21 queue after completing this discussion.
>>
>> On 01/28/2015 09:15 PM, Roger Quadros 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>
>>> ---
>>> v3:
>>> - removed IRQF_NO_SUSPEND flag. Added IRQF_TRIGGER_RISING and
>>> IRQF_TRIGGER_FALLING
>>> - Added disable_irq() to suspend() and enable_irq() to resume()
>>>
>>> .../devicetree/bindings/extcon/extcon-usb-gpio.txt | 18 ++
>>> drivers/extcon/Kconfig | 7 +
>>> drivers/extcon/Makefile | 1 +
>>> drivers/extcon/extcon-usb-gpio.c | 233 +++++++++++++++++++++
>>> 4 files changed, 259 insertions(+)
>>> create mode 100644 Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
>>> create mode 100644 drivers/extcon/extcon-usb-gpio.c
>>>
>>> diff --git a/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt b/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
>>> new file mode 100644
>>> index 0000000..85fe6b0
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt
>>> @@ -0,0 +1,18 @@
>>> +USB GPIO Extcon device
>>> +
>>> +This is a virtual device used to generate USB cable states from the USB ID pin
>>> +connected to a GPIO pin.
>>> +
>>> +Required properties:
>>> +- compatible: Should be "linux,extcon-usb-gpio"
>>> +- id-gpio: gpio for USB ID pin. See gpio binding.
>>> +
>>> +Example:
>>> + extcon_usb1 {
>>> + compatible = "linux,extcon-usb-gpio";
>>> + id-gpio = <&gpio6 1 GPIO_ACTIVE_HIGH>;
>>> + }
>>> +
>>> + &omap_dwc3_1 {
>>> + extcon = <&extcon_usb1>;
>>> + };
>>> diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
>>> index 6a1f7de..fd11536 100644
>>> --- a/drivers/extcon/Kconfig
>>> +++ b/drivers/extcon/Kconfig
>>> @@ -93,4 +93,11 @@ config EXTCON_SM5502
>>> Silicon Mitus SM5502. The SM5502 is a USB port accessory
>>> detector and switch.
>>>
>>> +config EXTCON_USB_GPIO
>>> + tristate "USB GPIO extcon support"
>>> + select GPIOLIB
>>
>> I catch the build warning if using 'select' instead of 'depends on' as following:
>> It is my wrong guide to you. So, I'll modify it by using "depends on" as your original patch.
>
> OK. Thanks.
>
>>
>> make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- zImage -j 8
>> scripts/kconfig/conf --silentoldconfig Kconfig
>> drivers/gpio/Kconfig:34:error: recursive dependency detected!
>> drivers/gpio/Kconfig:34: symbol GPIOLIB is selected by EXTCON_USB_GPIO
>> drivers/extcon/Kconfig:96: symbol EXTCON_USB_GPIO depends on EXTCON
>> drivers/extcon/Kconfig:1: symbol EXTCON is selected by CHARGER_MANAGER
>> drivers/power/Kconfig:316: symbol CHARGER_MANAGER depends on POWER_SUPPLY
>> drivers/power/Kconfig:1: symbol POWER_SUPPLY is selected by HID_SONY
>> drivers/hid/Kconfig:670: symbol HID_SONY depends on NEW_LEDS
>> drivers/leds/Kconfig:8: symbol NEW_LEDS is selected by BCMA_DRIVER_GPIO
>> drivers/bcma/Kconfig:75: symbol BCMA_DRIVER_GPIO depends on GPIOLIB
>>
>>> + help
>>> + Say Y here to enable GPIO based USB cable detection extcon support.
>>> + Used typically if GPIO is used for USB ID pin detection.
>>> +
>>> endif # MULTISTATE_SWITCH
>>> diff --git a/drivers/extcon/Makefile b/drivers/extcon/Makefile
>>> index 0370b42..6a08a98 100644
>>> --- a/drivers/extcon/Makefile
>>> +++ b/drivers/extcon/Makefile
>>> @@ -12,3 +12,4 @@ obj-$(CONFIG_EXTCON_MAX8997) += extcon-max8997.o
>>> obj-$(CONFIG_EXTCON_PALMAS) += extcon-palmas.o
>>> obj-$(CONFIG_EXTCON_RT8973A) += extcon-rt8973a.o
>>> obj-$(CONFIG_EXTCON_SM5502) += extcon-sm5502.o
>>> +obj-$(CONFIG_EXTCON_USB_GPIO) += extcon-usb-gpio.o
>>> diff --git a/drivers/extcon/extcon-usb-gpio.c b/drivers/extcon/extcon-usb-gpio.c
>>> new file mode 100644
>>> index 0000000..99a58b2
>>> --- /dev/null
>>> +++ b/drivers/extcon/extcon-usb-gpio.c
>>> @@ -0,0 +1,233 @@
>>> +/**
>>> + * drivers/extcon/extcon-usb-gpio.c - USB GPIO extcon driver
>>> + *
>>> + * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
>>> + * Author: Roger Quadros <rogerq@...com>
>>> + *
>>> + * This program is free software; you can redistribute it and/or modify
>>> + * it under the terms of the GNU General Public License version 2 as
>>> + * published by the Free Software Foundation.
>>> + *
>>> + * This program is distributed in the hope that it will be useful,
>>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>>> + * GNU General Public License for more details.
>>> + */
>>> +
>>> +#include <linux/extcon.h>
>>> +#include <linux/init.h>
>>> +#include <linux/interrupt.h>
>>> +#include <linux/irq.h>
>>> +#include <linux/kernel.h>
>>> +#include <linux/module.h>
>>> +#include <linux/of_gpio.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/workqueue.h>
>>> +
>>> +#define USB_GPIO_DEBOUNCE_MS 20 /* ms */
>>> +
>>> +struct usb_extcon_info {
>>> + struct device *dev;
>>> + struct extcon_dev *edev;
>>> +
>>> + struct gpio_desc *id_gpiod;
>>> + int id_irq;
>>> + bool id_irqwake; /* ID wakeup enabled flag */
>>
>> Do you really think id_irqwake is necessary?
>> I think it is not necessary.
>
> I will explain below why it is necessary.
>
>>
>>> +
>>> + unsigned long debounce_jiffies;
>>> + struct delayed_work wq_detcable;
>>> +};
>>> +
>>> +/* List of detectable cables */
>>> +enum {
>>> + EXTCON_CABLE_USB = 0,
>>> + EXTCON_CABLE_USB_HOST,
>>> +
>>> + EXTCON_CABLE_END,
>>> +};
>>> +
>>> +static const char *usb_extcon_cable[] = {
>>> + [EXTCON_CABLE_USB] = "USB",
>>> + [EXTCON_CABLE_USB_HOST] = "USB-Host",
>>> + NULL,
>>> +};
>>> +
>>
>> [snip]
>>
>>> +
>>> +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);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +#ifdef CONFIG_PM_SLEEP
>>> +static int usb_extcon_suspend(struct device *dev)
>>> +{
>>> + struct usb_extcon_info *info = dev_get_drvdata(dev);
>>> +
>>> + if (device_may_wakeup(dev))
>>> + if (!enable_irq_wake(info->id_irq))
>>> + info->id_irqwake = true;
>>> +
>>
>> You can simplify this code as following without 'id_irqwake':
>>
>> if (device_may_wakeup(dev))
>> enable_irq_wake(info->id_irq);
>
> enable_irq_wake() can fail. And if it does we need to keep track of it
> to prevent unbalanced disable_irq_wake() call in resume().
> That's the reason I've added the id_irqwake flag in struct usb_extcon_info.
It is not proper solution using id_irqwake. If fail to execute enable_irq_wake(),
usb_extcon_suspend() function have to return error immediately.
>
>>
>>> + /*
>>> + * We don't want to process any IRQs after this point
>>> + * as GPIOs used behind I2C subsystem might not be
>>> + * accessible until resume completes. So disable IRQ.
>>> + */
>>> + disable_irq(info->id_irq);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int usb_extcon_resume(struct device *dev)
>>> +{
>>> + struct usb_extcon_info *info = dev_get_drvdata(dev);
>>> +
>>> + if (info->id_irqwake) {
>>> + disable_irq_wake(info->id_irq);
>>> + info->id_irqwake = false;
>>> + }
>>
>> ditto.
>>
>> if (device_may_wakeup(dev))
>> disable_irq_wake(info->id_irq);
>>
>>> +
>>> + enable_irq(info->id_irq);
>>> +
>>> + return 0;
>>> +}
>>> +#endif
>>> +
>>> +static SIMPLE_DEV_PM_OPS(usb_extcon_pm_ops,
>>> + usb_extcon_suspend, usb_extcon_resume);
>>> +
>>> +static struct of_device_id usb_extcon_dt_match[] = {
>>> + { .compatible = "linux,extcon-usb-gpio", },
>>> + { /* sentinel */ }
>>> +};
>>> +MODULE_DEVICE_TABLE(of, usb_extcon_dt_match);
>>> +
>>> +static struct platform_driver usb_extcon_driver = {
>>> + .probe = usb_extcon_probe,
>>> + .remove = usb_extcon_remove,
>>> + .driver = {
>>> + .name = "extcon-usb-gpio",
>>> + .pm = &usb_extcon_pm_ops,
>>> + .of_match_table = usb_extcon_dt_match,
>>> + },
>>> +};
>>> +
>>> +module_platform_driver(usb_extcon_driver);
>>> +
>>> +MODULE_AUTHOR("Roger Quadros <rogerq@...com>");
>>> +MODULE_DESCRIPTION("USB GPIO extcon driver");
>>> +MODULE_LICENSE("GPL v2");
Thanks,
Chanwoo
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