On 14/12/16 21:22, Peter Rosin wrote: > On 2016-12-14 18:54, Jon Hunter wrote: ... >> Hmmm ... looking closer at the schematics I see a power-MOSFET in the >> path of the ACOK to the Tegra and it looks like this could be inverting >> the signal! Seems this was not caught when the code was submitted. This >> should have been described in the device-tree somewhere :-( > > That's what I suspected... > > Ok, I expect the ship has sailed and that it's too late to actually fix > this up with active-low in various Tegra dts files and removing the negation > in the code, without causing ripples and regressions? Because that would > be the clean fix! Yes, unfortunately it has sailed as we cannot break compatibility AFAIK. However, that said, I am not 100% certain for cases where there is a bug like this. I did double check this morning and verified that the gpio is low when the charger is connected and so it is inverted. > One other thing to possibly do is add a new binding that is not negated, > and perhaps named after the pin in the data-sheet, i.e. ti,acok-gpios, > and deprecate ti,ac-detect-gpios. But that's no fun as it leaves a bunch of > compat code that wastes space and some lucky person has to maintain it. > > Perhaps the best thing to do is to just re-document ti,ac-detect-gpios > to be the inverse of what is currently described, i.e. to be AC absence > instead of AC presence? But that feels like giving up and it isn't really > nice from a device-tree point of view either, but I guess those points are > fairly accademic? Or are there any non-Linux users of this binding? How are > these things handled when they pop up elsewhere? I guess that ideally the polarity should have been specified correctly by the gpio property, but even this looks wrong for Tegra as it is GPIO_ACTIVE_HIGH and not LOW. The only other option is to add another property called something like 'ti,ac-detect-override-pol' to specify the polarity you want. To be honest, I am not sure how this type of thing is normally handled. So probably best to put together a patch with whatever option you feel best and explain why this is needed and see what the dev-tree folks say. Cheers Jon -- nvpublic -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
