Messages in this thread | | | Date | Tue, 11 Dec 2012 13:49:05 -0700 | From | Stephen Warren <> | Subject | Re: [PATCH 2/2] pinctrl: skip deferral of hogs |
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On 12/11/2012 06:36 AM, Linus Walleij wrote: > From: Linus Walleij <linus.walleij@linaro.org> > > Up until now, as hogs were always taken at the end of the > pin control device registration, it didn't cause any problem. > But when starting to hog pins from the device core it will > cause deferral of the pin controller device itself since the > default pin fetch is done *before* the device probes, so > let's fix this annoyance (which is also aesthetically ugly).
I guess this is OK, although I can't quite get over the feeling of it being a bit of a hack.
The issue is IIUC that the driver core is going to call pinctrl_get() for any device before it's probed, and if it succeeds it will select the default state, but this patch deliberately fails the pinctrl_get() for a pin controller, and hence relies on pinctrl_register() making a second attempt at pinctrl_get(), and also activating the default state there. That's a bit of duplication and rather asymmetric.
That all said, I don't really see what we can do better, so I won't object!
Oh, one comment on the patch. It returns -ENODEV as soon as any hog is seen. Just in case someone does something wierd, shouldn't it accumulate the "worst-case" return value and not return early? Consider a pin controller whose mapping table entries contain both hogs, /and/ entries that use a different pin controller. That's a little contrived, but trivial to actually do. As such, I think we want something more like:
ret = 0 for every mapping table entry: if can't find pinctrl device: if map entry is a hog: # Requiring defer is a worst case, so defer the return! ret = -ENODEV else: # This is worst-case, so can return now return -EPROBE_DEFER if ret: cleanup return ret
That way, if a mapping table entry requiring defer comes after a hog, we'll still return the correct value.
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