On Mon, Dec 13, 2021 at 2:25 PM Jerome Brunet <jbrunet@xxxxxxxxxxxx> wrote: > > > On Mon 13 Dec 2021 at 19:50, "rong.chen@xxxxxxxxxxx" <rong.chen@xxxxxxxxxxx> wrote: > > > Hello, > > If 3.3V always-on power source for vmmc is supplied by hardware boards fixed, don't need regulator in software, so .dts unnecessary the link between regulator > > and MMC controller vmmc/vqmmc. > > Controllable or not, your vmmc/vqmmc regulators should be described in > DT. I agree with Jerome. Here are the two reasons why I think that it's best to describe these regulators in device-tree: - device-tree is there to describe the hardware. It's especially useful for non-discoverable information (USB and PCI IDs are discoverable examples), for example: voltage supply of an MMC controller, UART IRQ line, ... - reviewing board.dts would be a lot harder if we rely on defaults (defaults which cannot be described in a device-tree schema). For meson-g12a-radxa-zero.dts this means we could omit the vmmc/vqmmc regulators for the SD card slot but we need them for the eMMC (because vqmmc is fixed at 1.8V). Best regards, Martin
