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SubjectRe: [PATCH 1/2] pinctrl: palmas: do not abort pin configuration for BIAS_DEFAULT
On Friday 27 September 2013 09:36 PM, Stephen Warren wrote:
> On 09/27/2013 07:30 AM, Laxman Dewangan wrote:
>> On Thursday 26 September 2013 09:08 PM, Stephen Warren wrote:
>>> On 09/26/2013 06:48 AM, Laxman Dewangan wrote:
>>>> Recent movement of all configurations of pin in the single call of
>>>> pin_config_set(), it is aborting configuration if BIAS_PULL_PIN_DEFAULT
>>>> is selected as return of configuration.
>>>>
>>>> The original idea was to just avoid any update on register for pull
>>>> up/down
>>>> configuration if this option is selected.
>>> That doesn't sound correct. If a config option is specified in DT or the
>>> mapping table, it should be applied to HW. If someone doesn't want a
>>> particular config option applied, then it simply shouldn't be mentioned
>>> in DT or the mapping table.
>>>
>>> IIUC, BIAS_DEFAULT should be used only on HW where there is a concept of
>>> a true default bias, and in that case, that is what should be applied.
>>>
>> Hmm.. When I added the PIN_DEFAULT, I just though that do not update
>> anything in the register and implemented like that.
>> There is nothing "default" option in HW.
> The description of that pinconfig option is:
>
>> 7970cb77 (Heiko Stübner 2013-06-06 16:44:25 +0200 43) * @PIN_CONFIG_BIAS_PULL_PIN_DEFAULT: the pin will be pulled up or down based
>> 70637a6d (Heiko Stübner 2013-06-25 14:55:42 +0200 44) * on embedded knowledge of the controller hardware, like current mux
>> 70637a6d (Heiko Stübner 2013-06-25 14:55:42 +0200 45) * function. The pull direction and possibly strength too will normally
>> 70637a6d (Heiko Stübner 2013-06-25 14:55:42 +0200 46) * be decided completely inside the hardware block and not be readable
>> 70637a6d (Heiko Stübner 2013-06-25 14:55:42 +0200 47) * from the kernel side.
>> 5ca3353b (Linus Walleij 2013-06-16 12:43:06 +0200 48) * If the argument is != 0 pull up/down is enabled, if it is 0, the
>> 5ca3353b (Linus Walleij 2013-06-16 12:43:06 +0200 49) * configuration is ignored. The proper way to disable it is to use
>> 5ca3353b (Linus Walleij 2013-06-16 12:43:06 +0200 50) * @PIN_CONFIG_BIAS_DISABLE.
> If the HW doesn't support any concept of a default pull, I think the
> driver shouldn't support that option; it should return an error if asked
> to program it.

Yes, I will remove this option as I have not seen default option for pins.

>
>
> But what made you come across this issue? Is some pin mapping table or
> DT pinctrl node actually using that value? If so, then presumably that
> needs to be fixed, as well as removing driver support for that option.

When referring the code for the AMSAS3722 pincontrol driver, I just
found that it is breaking the earlier code.

Removing this option makes more reasonable here and will post the next
patch.

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