Hi George,
On 08/29/2013 10:45 PM, George Cherian wrote:
> Hi Chanwoo,
>
>
> On 8/29/2013 5:42 PM, Chanwoo Choi wrote:
> [big snip ]
>>>> I tested various development board based on Samsung Exynos series SoC.
>>>> Although some gpio of Exynos series SoC set high state(non zero, 1) as
>>>> default value,
>>>> this gpio state could mean off state, disconnected or un-powered state
>>>> according to gpio.
>>>> Of course, above explanation about specific gpio don't include all gpios.
>>>> This is meaning that there is possibility.
>>> okay then how about adding a flag for inverted logic too. something like
>>> this
>>>
>>> if(of_property_read_bool(np,"inverted_gpio))
>>> gpio_usbvid->gpio_inv = 1;
>>> And always check on this before deciding?
> Is this fine ?
OK.
But, as Stephen commented on other mail, you should use proper DT helper
function.
>>>
>>>>>> Second,
>>>>>> gpio_usbvid_set_initial_state() dertermine both "USB-HOST" and "USB"
>>>>>> cable state at same time
>>>>>> in 'case ID_DETCT' according to 'gpio_usbvid->id_gpio'. But, I think
>>>>>> that other extcon devices
>>>>>> would not control both "USB-HOST" and "USB" cable state at same time.
>>>>>>
>>>>>> Other extcon devices would support either "USB-HOST" or "USB" cable.
>>>>> The driver has 2 configurations.
>>>>> 1) supports implementations with both VBUS and ID pin are routed via
>>>>> gpio's for swicthing roles(compatible gpio-usb-vid).
>>>> As you explained about case 1, it is only used on dra7x SoC.
>>> No gpio-usb-id is used in dra7xx. dra7xx has got only ID pin routed via
>>> gpio.
>>>> Other SoC could not wish to control both "USB-HOST" and "USB" cable at
>>>> same time.
> I could'nt actually parse this. You meant since the id_irq_handler handles
> both USB and USB-HOST cable
> its not proper?
It's not proper in general case. The generic driver must guarantee all of
extcon device using gpio.
As far as I know, the generic driver cannot direclty control gpio pin and get
value from gpio pin.
Almost device driver including in kernel/drivers control gpio pin on specific
device driver
instead of generic driver.
>> I need your answer about above my opinion for other SoC.
> So how about this, I have removed the dra7x specific stuffs (gpio-usb-id)
>
> static void gpio_usbvid_set_initial_state(struct gpio_usbvid *gpio_usbvid)
> {
> int id_current, vbus_current;
>
> id_current = gpio_get_value_cansleep(gpio_usbvid->id_gpio);
> if (!!id_current == ID_FLOAT)
> extcon_set_cable_state(&gpio_usbvid->edev, "USB-HOST", false);
> else
> extcon_set_cable_state(&gpio_usbvid->edev, "USB-HOST", true);
>
> vbus_current = gpio_get_value_cansleep(gpio_usbvid->vbus_gpio);
> if (!!vbus_current == VBUS_ON)
> extcon_set_cable_state(&gpio_usbvid->edev, "USB", true);
> else
> extcon_set_cable_state(&gpio_usbvid->edev, "USB", false);
> }
>
> and the irq handlers like this
>
> static irqreturn_t id_irq_handler(int irq, void *data)
> {
> struct gpio_usbvid *gpio_usbvid = (struct gpio_usbvid *)data;
> int id_current;
>
> id_current = gpio_get_value_cansleep(gpio_usbvid->id_gpio);
> if (id_current == ID_GND)
> extcon_set_cable_state(&gpio_usbvid->edev, "USB-HOST", true);
> else
> extcon_set_cable_state(&gpio_usbvid->edev, "USB-HOST", false);
> return IRQ_HANDLED;
> }
>
> static irqreturn_t vbus_irq_handler(int irq, void *data)
> {
> struct gpio_usbvid *gpio_usbvid = (struct gpio_usbvid *)data;
> int vbus_current;
>
> vbus_current = gpio_get_value_cansleep(gpio_usbvid->vbus_gpio);
> if (vbus_current == VBUS_OFF)
> extcon_set_cable_state(&gpio_usbvid->edev, "USB", false);
> else
> extcon_set_cable_state(&gpio_usbvid->edev, "USB", true);
>
> return IRQ_HANDLED;
> }
I know your intention dividing interrupt handler for each cable.
But I don't think this driver must guarantee all of extcon device using gpio.
For example,
below three SoC wish to detect USB/USB-HOST cable with each different methods.
"SoC A" wish to detect USB/USB-HOST cable through only one gpio pin.
"SoC B" wish to detect USB/USB-HOST cable through ADC value instead of gpio pin.
"SoC C" wish to detect USB/USB-HOST cable through two gpio pin because USB
connected on gpio an USB-HOST connected on another.
In addition,
if "SoC A/C" wish to write some data to own specific registers for proper
opeating,
Could we write some data to register on generic driver?
Finally,
"SoC D" wish to detect USB/USB-HOST/JIG cable through two gpio pin
- one gpio may detect either USB or USB-HOST and another may detect JIG cable
or one gpio may detect either USb or JIG and another may detect USB-HOST cable.
That way, there are many cases we cannot guarantee all of extcon devices.
I think this driver could support dra7x series SoC but as I mentioned,
this driver may not guarantee all of cases.
> [snip]
>>>> I have some confusion. I need additional your explanation.
>>>> Could this driver register only one interrupt handler either
>>>> id_irq_handler() or vbus_irq_handler()?
>>> If compatible == ID_DETECT, only one handler --> id_irq_handler() and it
>>> will handle both USB and USB-HOST
>>>> or
>>>> Could this driver register two interrupt handler both id_irq_handler() or
>>>> vbus_irq_handler()?
>>> If compatible == VBUS_ID_DETECT, 2 handlers --> id_irq_handler() will
>>> handle USB-HOST and vbus_irq_handler will handle USB.
>> As you mentioned, we cannot only control either USB or USB-HOST cable on
>> this extcon driver.
>> This extcon driver is only suitable dra7x SoC.
> Do you still feel its dra7x specific if i modify it as above?
I commented above about your modification.
>> Because id_irq_handler() control both "USB-HOST" and "USB" cable at same
>> time,
>> you need this setting order between "USB-HOST" and "USB" cable.
>>> yes
>> I think that the setting order between cables isn't general. It is specific
>> method for dra7x SoC.
> So if i remove that part then?
The setting order should be removed in generic driver.
>>>> Did you think that SoC should always connect either "USB-HOST" cable or
>>>> "USB" cable?
>>> No, even if a physical cable is not connected it should default to either
>>> USB-HOST or USB
>> It isn't general.
>>
>> If physical cable isn't connected to extcon device, the state both USB-HOST
>> and USB cable
>> should certainly be zero. Because The extcon consumer driver could set
>> proper operation
>> according to cable state.
> okay
>>
>>>
>>>> I don't know this case except for dra7x SoC. So, I think it has dependency
>>>> on specific SoC.
>> I need your answer about above my opinion.
> Hope i could answer you :-)
>>>> and can't agree as generic extcon gpio driver.
>>
>
Thanks,
Chanwoo Choi
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