From: Jan Kiszka <jan.kiszka@siemens.com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>,
"Enrico Weigelt, metux IT consult" <lkml@metux.net>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Linus Walleij <linus.walleij@linaro.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Subject: Re: [PATCH 2/2] gpio: sch: Add interrupt support
Date: Fri, 26 Apr 2019 19:52:48 +0200 [thread overview]
Message-ID: <0e9b6e72-d7d8-6dea-4efa-4eb7c1a8e0c9@siemens.com> (raw)
In-Reply-To: <20190426174645.GB31161@Mani-XPS-13-9360>
On 26.04.19 19:46, Manivannan Sadhasivam wrote:
> On Fri, Apr 26, 2019 at 07:39:56PM +0200, Jan Kiszka wrote:
>> On 26.04.19 19:33, Manivannan Sadhasivam wrote:
>>> On Fri, Apr 26, 2019 at 08:20:19PM +0300, Andy Shevchenko wrote:
>>>> On Fri, Apr 26, 2019 at 7:05 PM Jan Kiszka <jan.kiszka@siemens.com> wrote:
>>>>>
>>>>> On 26.04.19 16:42, Enrico Weigelt, metux IT consult wrote:
>>>>>> On 26.04.19 15:36, Jan Kiszka wrote:
>>>>>>
>>>>>>> At the same time, there are no real alternatives - to my> knowledge - for the value it brings (various bindings) to simply
>>>>>> switch> the engine.
>>>>>> Which value exactly does that collection of crude wrappers and broken
>>>>>> attempts to buypass the kernel (driving gpios via /dev/mem *facepalm*)
>>>>>> provide ?
>>>>>
>>>>> Leaving that blunt hack aside:
>>>>>
>>>>> import mraa
>>>>>
>>>>> pin = mraa.Gpio(13)
>>>>> pin.dir(mraa.DIR_OUT)
>>>>> pin.write(1)
>>>>>
>>>>> And the same goes for nodejs, java and c++.
>>>>>
>>>>> Moreover, this allows you to abstract away where "Pin 13" actually came from on
>>>>> that board if the kernel changes (BSP -> upstream...) or the extension board or
>>>>> ...
>>>>
>>>> The problem here is opaque number. This has to be chip + *relative* pin number/
>>>> See this:
>>>> https://stackoverflow.com/questions/55532410/how-do-linux-gpio-numbers-get-their-values/55579640#55579640
>>>>
>>>
>>> But for platform like 96Boards we don't need controller specific lookup, these
>>> are all handled by the platform code [1] so that the users can use the standard
>>> pinout number to access GPIOs. For instance, pin 23 on the Low Speed expansion
>>> header is the GPIO for all 96Boards platform, so the user can access that pin
>>> using 23 itself in the application and it will run across all supported
>>> 96Boards.
>>
>> Can you ensure stable numbering when probing order changes, e.g. due to
>> adding an extension board?
>>
>
> Good point! For tackling this, I'm planning to introduce an API for accessing
> the GPIO by its line name. It will be tricky to implement but once done, it
> will serve.
Whatever is stable and handy. As cited in the other thread, I played with the
device path as well, see [1][2]. Feel free to pick what what is useful, I will
likely not have time to work on that soon again.
Jan
[1] https://github.com/siemens/mraa/commit/034d787eea1a5b201ea77a6549ffc0bdbc3b776d
[2] https://github.com/siemens/mraa/commit/6fd8a3c27764718c1e62a4938a6dc88819c3f65f
--
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux
next prev parent reply other threads:[~2019-04-26 17:53 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-18 9:23 [PATCH 0/2] gpio: sch: Interrupt support Jan Kiszka
2019-04-18 9:23 ` [PATCH 1/2] gpio: sch: Remove write-only core_base Jan Kiszka
2019-04-23 11:09 ` Linus Walleij
2019-04-18 9:23 ` [PATCH 2/2] gpio: sch: Add interrupt support Jan Kiszka
2019-04-23 11:10 ` Linus Walleij
2019-04-24 7:58 ` Mika Westerberg
2019-04-24 8:12 ` Jan Kiszka
2019-04-24 8:18 ` Mika Westerberg
2019-04-24 8:25 ` Jan Kiszka
2019-04-24 8:42 ` Mika Westerberg
2019-04-24 9:36 ` Jan Kiszka
2019-04-24 9:45 ` Mika Westerberg
2019-04-24 9:48 ` Jan Kiszka
2019-04-24 10:01 ` Mika Westerberg
2019-04-24 10:19 ` Jan Kiszka
2019-04-24 10:33 ` Mika Westerberg
2019-04-24 10:39 ` Jan Kiszka
2019-04-24 10:46 ` Mika Westerberg
2019-04-24 12:41 ` Jan Kiszka
2019-04-24 13:13 ` Mika Westerberg
2019-04-24 14:24 ` Jan Kiszka
2019-04-24 15:33 ` Mika Westerberg
2019-04-26 13:06 ` Andy Shevchenko
2019-04-26 13:36 ` Jan Kiszka
2019-04-26 14:42 ` Enrico Weigelt, metux IT consult
2019-04-26 15:31 ` Manivannan Sadhasivam
2019-04-26 16:03 ` Jan Kiszka
2019-04-26 17:20 ` Andy Shevchenko
2019-04-26 17:33 ` Manivannan Sadhasivam
2019-04-26 17:39 ` Jan Kiszka
2019-04-26 17:46 ` Manivannan Sadhasivam
2019-04-26 17:52 ` Jan Kiszka [this message]
2019-04-26 17:56 ` Manivannan Sadhasivam
2019-04-26 17:44 ` Andy Shevchenko
2019-04-26 17:52 ` Manivannan Sadhasivam
2019-04-26 18:26 ` Andy Shevchenko
2019-04-26 17:37 ` Jan Kiszka
2019-04-29 11:09 ` Enrico Weigelt, metux IT consult
2019-05-16 12:20 ` Linus Walleij
2019-04-26 14:41 ` Linus Walleij
2019-04-26 15:44 ` Jan Kiszka
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