On Tue, 2021-05-25 at 13:36 +0200, Thierry Reding wrote: > On Mon, May 24, 2021 at 01:51:51PM +0800, Chunfeng Yun wrote: > > On Fri, 2021-05-21 at 15:20 +0200, Thierry Reding wrote: > > > On Wed, May 19, 2021 at 02:39:46PM +0800, Chunfeng Yun wrote: > > > > Vbus is already an optional supply, if the vbus-supply is not > > > > provided in DTS, will use a dummy regulator, > > > > > > That statement is not entirely correct. The dummy regulator is > > > substituted only if the supply is in fact not optional. The idea behind > > > that is to allow DTS files that don't specify all required regulators to > > > get away with it, based on the assumption that the supply is one of > > > those always-on supplies that are often not described in DTS. > > Yes, you are right. > > But from the point of result, it indeed can help to handle the absent > > regulator. > > > > > > > the warning log is as below: > > > > "supply vbus not found, using dummy regulator" > > > > > > And the reason why we get that warning is to point out that the DTS has > > > a bug and that it should be fixed (by adding a proper regulator to take > > > the place of the dummy). > > > > > > > This reverts commit 4ddf1ac79e5f082451cd549283d2eb7559ab6ca9. > > > > > > But if you read the description of that commit, the purpose of that > > > patch was in fact to make the supply completely optional in the case > > > where we already have the VBUS supply specified for the USB port that > > > the connector is parented to. > > Could you please give an example you mentioned? > > You can find examples of this in these: > > arch/arm64/boot/dts/nvidia/tegra210-p2597.dtsi > arch/arm64/boot/dts/nvidia/tegra210-p3450-0000.dts > arch/arm64/boot/dts/nvidia/tegra186-p2771-0000.dts > > > It seems prefer to provide vbus supply in connector instead of port > > according to dt-binding > > My recollection is that the above (or at least some of them) predate USB > connectors. > > It's possible that we could convert the above to have the VBUS supply > listed in the connector instead of the port. However, since we have to > preserve backwards compatibility with older device trees, we can't > revert the commit anyway. Got it, thanks a lot > > Thierry
