Messages in this thread | | | Date | Fri, 31 Oct 2014 10:40:42 -0700 | From | Sören Brinkmann <> | Subject | Re: [PATCH RFC v2 8/8] ARM: zynq: DT: Add pinctrl information |
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On Fri, 2014-10-31 at 06:36PM +0100, Linus Walleij wrote: > On Fri, Oct 31, 2014 at 5:57 PM, Sören Brinkmann > <soren.brinkmann@xilinx.com> wrote: > > On Fri, 2014-10-31 at 09:17AM +0100, Linus Walleij wrote: > > >> Again it seems to be a sequencing problem. And device tree is > >> not good at sequences, therefore all states should be self-contained. > > > > I agree, but how would I define a pin with pull-up enabled and > > tri-state disabled - assume the pin is currently in a random state that > > can have those things set/not set arbitrarily. > > I was more thinking as everything you don't enable explicitly > in a state is per definition disabled. > > So if you are in state A and tri-state is enabled there and you > move to state B where pull-up is enabled, then tri-state should > be disabled, since it is not explicitly enabled. > > > I can't put bias-disable in DT since it would potentially disable both > > and the pull-up enable would have only a transient effect. > > Well look at the callback from the core: > > int (*pin_config_set) (struct pinctrl_dev *pctldev, > unsigned pin, > unsigned long *configs, > unsigned num_configs); > > You get all configs in an array. The driver can walk over the list and > make informed decisions on what to do *BEFORE* poking any registers. > > Avoiding transients as you describe is part of why the callback > looks as it does. This is why every driver has its own for-loop.
Okay, I guess that is possible. I find usage of the arguments more elegant since it is more explicit and reduces code in the driver, but I suspect it should work.
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