Messages in this thread | | | Date | Mon, 23 May 2022 15:53:22 +0200 | Subject | Re: [PATCH 2/4] regulator: Add driver for MT6331 PMIC regulators | From | AngeloGioacchino Del Regno <> |
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Il 23/05/22 15:43, Mark Brown ha scritto: > On Mon, May 23, 2022 at 03:22:39PM +0200, AngeloGioacchino Del Regno wrote: >> Il 23/05/22 15:00, Mark Brown ha scritto: > >>> Right, my point here is that it looks awfully like the documentation >>> (this came from documentation I guess?) is including some extra bits >>> that get ignored in the voltage selection field here. That seems like a >>> weird choice somewhere along the line. > >> I wish I had a datasheet for these parts... > >> All of this comes from analyzing a running device on the downstream 3.4 kernel >> and on understanding the (not really readable) downstream kernel code... >> ..but yes, I agree on the fact that this seems to be a weird choice. > >> Ah, besides, I hooked up an oscilloscope to the VCAM_IO and I can see that the >> vreg really does react as expected upon setting the upper bits.. but since it >> still works without, we can safely ignore them, which makes us able to simplify >> the driver (as no custom code for that will be required) and, at the same time, >> avoid seeing a table of values repeated 4 times in a row. > > That seems safer in general if we don't know what those bits are doing - > it could be some kind of mode control or something. > >> ...so, the regulator will indeed shut itself off and clear either/both the QI_EN >> and/or its relative bit in the enable register... I've also just found hints of >> the latter (enable register being set to 0) downstream, so I'm sure that this is >> indeed right. > > That's still not quite the same thing as a status bit, if the regulator > disables itself then it won't try to turn itself back on. Note that the > core will fall back on using the enable state if there's no status op so > there's no need for this logic, you can just omit the status op and the > behaviour will be the same.
Ok then, I'll simply remove that!
Thanks, Angelo
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