Messages in this thread | | | From | Andy Shevchenko <> | Date | Fri, 29 Jun 2018 18:29:45 +0300 | Subject | Re: [PATCH 0/5] pinctrl_gpio_get_direction & ingenic fixes |
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On Thu, Jun 28, 2018 at 10:11 PM, Paul Cercueil <paul@crapouillou.net> wrote: > Le mer. 27 juin 2018 à 19:18, Andy Shevchenko <andy.shevchenko@gmail.com> a > écrit : >> On Wed, Jun 27, 2018 at 2:48 PM, Paul Cercueil <paul@crapouillou.net> >> wrote:
>> I dunno what Linus would going to say about this, but I would like to >> see a schematics for this piece of IP.
> ftp://ftp.ingenic.com/SOC/JZ4780/JZ4780_pm.pdf
I'm not sure you referred to a proper document "Mobile Application Processor. Programming Manual"
I didn't find quickly what I'm looking for. Care to point me out to the page number? Thanks!
>> Even if GPIO and pin muxing has only one set of buffers to indicate >> input or output (same registers in use) it's a GPIO driver business to >> get direction from GPIO part of IP. > > > If I follow that logic it's also a GPIO driver business to set the direction > of a GPIO, right? Truth is the pinctrl subsystem takes care of that. So why > have "set direction" and no "get direction"?
Because it's a pin muxing business depending on the function chosen.
It solely depends on a schematic. For the example, everyone knows that MOSI is out always, otherwise SPI function would not work. .get_direction() has useful meaning only for GPIO function. (This is my understanding from electrical configuration of buffers).
>> Looking into the existing code I would rather say that >> pinctrl-ingenic.c should incorporate gpio-ingenic.c as they are >> (partially) sharing same registers. >> To ->get_direction() implementation it's pretty straight forward, just >> read necessary registers in the gpio-ingenic.c directly. No need to >> have pin control or pin muxing to be involved.
> Sure, it'd be pretty straightforward to do it from the GPIO driver, but I'd > still like to hear Linus' point of view about this.
Sure.
> As for merging pinctrl-ingenic.c and gpio-ingenic.c... I wouldn't disagree > more, > even if they share registers, they belong to different subsystems. Besides, > your platform might need the pinctrl driver but not the GPIO one, or you > might > want to provide the GPIO driver as a loadable module, etc.
It was just my observation, I'm not a maintainer of that code nor author, so, up to you how to proceed.
-- With Best Regards, Andy Shevchenko
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