On 06/11/2023 22:36, Hugo Villeneuve wrote: > On Mon, 6 Nov 2023 21:39:42 +0100 > Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> wrote: > >> On 06/11/2023 19:57, Hugo Villeneuve wrote: >>> From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx> >>> >>> The following warning is shown when probing device: >>> >>> pca953x 1-0020: supply vcc not found, using dummy regulator >>> >>> Add fixed 3.3v regulator as vcc supply to silence the warning. >>> >> >> This is not really a warning. It's perfectly fine to use dummy >> regulator. Adding such fixed supply has sense in following cases: >> 1. Bindings require the supply, >> 2. This is in fact exactly that supply (verified on schematics). >> >> Best regards, >> Krzysztof > > Hi Krzysztof, > this is case #2, but looking more closely at the carrier board > (symphony) schematics, it is not exactly the "reg_3v3_fixed" supply I > mentioned in the patch, as "reg_3v3_fixed" is located on the SOM and > only powers SOM components. > > However, "reg_3v3_fixed", which is an always-on regulator (no software > enable control), is used as the enable input to a mosfet switch (Q2) on > the carrier board to generate the 3.3V (label BASE_PER_3V3 on the > schematics) used by all peripherals on that carrier board. > > I guess I could then define a new "always-on" regulator labeled as, > for example, base_per_3v3, and then assign the pca953x vcc-supply > property to it? I guess this could be the same supply, even if this is not 100% true. However it would be good if you put above explanation in the commit msg. Best regards, Krzysztof
