Messages in this thread | | | Date | Mon, 9 Jun 2008 19:09:00 +0200 (CEST) | From | Guennadi Liakhovetski <> | Subject | Re: [RFC] generic GPIO parameter API |
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On Mon, 9 Jun 2008, Mark Brown wrote:
> On Mon, Jun 09, 2008 at 06:23:50PM +0200, Guennadi Liakhovetski wrote: > > On Thu, 5 Jun 2008, David Brownell wrote: > > > On Monday 02 June 2008, Guennadi Liakhovetski wrote: > > > > > as far as I understand, the current GPIO API only presents very basic GPIO > > > > functionality: direction and level reading and writing. Whereas many GPIO > > > > controllers have many further configurable parameters: pull-ups and > > > > pull-downs, drive strength, slew rate, etc. > > > > Not at all how I'd describe it. Those omitted mechanisms are part > > > of pin configuration, in the same way as function multiplexing is. > > > (That is, assigning a given pin for use as a GPIO, vs hooking it up > > > to an I2C, MMC, SPI, LCD, I2S, or memory controller.) > > > Yes, on the one hand you're right, this belongs to pin-configuration. But, > > otoh, will anyone ever want to change these parameters on non-generic > > pins? And should this be allowed? Whereas for GPIOs it clearly makes a > > They do get configured like that - for example, most I2S devices are > able to operate as both clock masters and clock slaves. Often this > accomplished (at least in part) by configuring the relevant pins as > inputs or outputs.
The primary purpose of the GPIO-parameter proposal was to allow to configure these parameters from the user-space over sysfs by extending the gpio-sysfs patch. And I2S master / slave operation should not be switchable over sysfs, should it?
Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer
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