From: b.brezillon@overkiz•com (boris brezillon)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC PATCH alt 4/4] pinctrl: at91: rework debounce configuration
Date: Mon, 16 Sep 2013 19:18:37 +0200 [thread overview]
Message-ID: <52373D6D.4010109@overkiz.com> (raw)
In-Reply-To: <523734B2.6050208@wwwdotorg.org>
Hello Stephen,
On 16/09/2013 18:41, Stephen Warren wrote:
> On 09/14/2013 01:08 AM, boris brezillon wrote:
>> Hello Stephen,
>>
>> Le 14/09/2013 00:40, Stephen Warren a ?crit :
>>> On 09/13/2013 01:53 AM, Boris BREZILLON wrote:
>>>> AT91 SoCs do not support per pin debounce time configuration.
>>>> Instead you have to configure a debounce time which will be used for all
>>>> pins of a given bank (PIOA, PIOB, ...).
> ...
>>>> Required properties for pin configuration node:
> ...
>>>> -DEBOUNCE_VAL (0x3fff << 17): debounce val.
>>> This change would break the DT ABI since it removes a feature that's
>>> already present.
> ...
>>> I suppose it's still up to the Atmel maintainers to decide whether this
>>> is appropriate, or whether the impact to out-of-tree DT files would be
>>> problematic.
>>>
>>> Assuming the DT ABI can be broken, I think I'd prefer to do so, rather
>>> than take "non-alt" patch 4/4, since a per-pin DEBOUNCE_VAL clearly
>>> doesn't correctly model the HW, assuming the patch description is
>>> correct. I don't think arguments re: the generic pinconf debounce
>>> property hold; if the Linux-specific/internal generic property doesn't
>>> apply, the DT binding should not be bent to adjust to it, but should
>>> rather still represent the HW itself.
>> What about the last point in my list: "reconfigure debounce after
>> startup" ?
>>
>> Here is an example that may be problematic:
>>
>> Let's say you have one device using multiple configuration of pins
>> ("default", "xxx", "yyy").
>> The "default" config needs a particular debounce time on a given pin and
>> the "xxx" and "yyy"
>> configs need different debounce time on the same pin.
>>
>> How would you solve this with this patch approach ?
> Each state has a different pin configuration node, and hence can specify
> a different debounce value. This patch has no impact on that (it just
> changes whether the state-specific node specifies the debounce value in
> a single standalone property, or encodes it into each entry in the pins
> property, all within the same node).
Actually it does: this patch removes the debounce time setting option from
the pin config description. The only thing you can do is enable or
disable the
debounce filter.
The atmel,default-debounce-div property is not part of the pin group (or
pin state)
node, it is a global property you define for the whole pinctrl
controller (pinctrl node
property):
pinctrl {
atmel,default-debounce-div=<100 /* PIOA div <=> ~3 ms */
50 /* PIOB
div */
...>;
function {
group {
atmel,pins=<...>;
};
};
};
I can get the debounce time option in a separate property (as you're
suggesting):
pinctrl {
function {
group {
atmel,debounce=<1000>; /* debounce in usec */
atmel,pins=<...>;
};
};
};
but it won't solve the primary issue, that is all the pin on a given
bank (PIOA1 PIOA2, ...)
share the same debounce time.
Please tell me if I misunderstood your suggestion.
Best Regards,
Boris
next prev parent reply other threads:[~2013-09-16 17:18 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-13 7:43 [RFC PATCH 0/4] pinctrl: at91: various fixes Boris BREZILLON
2013-09-13 7:45 ` [RFC PATCH 1/4] pinctrl: at91: fix typos Boris BREZILLON
2013-09-14 16:45 ` Jean-Christophe PLAGNIOL-VILLARD
2013-09-27 12:10 ` Linus Walleij
2013-09-13 7:47 ` [RFC PATCH 2/4] pinctrl: at91: fix sam9x5 debounce/deglitch functions Boris BREZILLON
2013-09-14 16:49 ` Jean-Christophe PLAGNIOL-VILLARD
2013-09-27 12:12 ` Linus Walleij
2013-09-13 7:49 ` [RFC PATCH 3/4] pinctrl: at91: improve pinconf_set/get function robustness Boris BREZILLON
2013-09-14 16:55 ` Jean-Christophe PLAGNIOL-VILLARD
2013-09-13 7:51 ` [RFC PATCH 4/4] pinctrl: at91: check for debounce time conflicts Boris BREZILLON
2013-09-13 7:53 ` [RFC PATCH alt 4/4] pinctrl: at91: rework debounce configuration Boris BREZILLON
2013-09-13 22:40 ` Stephen Warren
2013-09-14 7:08 ` boris brezillon
2013-09-16 16:41 ` Stephen Warren
2013-09-16 17:18 ` boris brezillon [this message]
2013-09-16 18:14 ` Stephen Warren
2013-09-14 16:31 ` Jean-Christophe PLAGNIOL-VILLARD
2013-09-14 16:37 ` Jean-Christophe PLAGNIOL-VILLARD
2013-09-15 6:21 ` boris brezillon
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