On Fri, May 29, 2026 at 03:15:03PM +0100, Daniel Thompson wrote: > On Fri, May 29, 2026 at 02:50:43PM +0200, Neil Armstrong wrote: > > On 5/29/26 12:35, Daniel Thompson wrote: > > > On Fri, May 29, 2026 at 12:16:07PM +0200, Neil Armstrong wrote: > > So it's not really 2 regulators, and having regulators means the enable > > signal can be shared and would have regulator characteristics which it > > hasn't. > > Agreed. If the EN pin is merely use as an enable and voltage reference > then it are not two regulators. > > However, it is also *not* vddio-supply and enable-gpios. We don't need > the board design to check this. The pinout diagram in the datasheet > should be sufficient! > > If you have to activate vddio-supply for the backlight to work on the > board are you sure you don't just have a misnamed vdd-supply that needs > to be taken care of? That would make much more sense given the datasheet.
After posting this I figured there is another possibility. If the host GPIO pin is not capable of delivering the 1mA requires by the chip then the board designer would have to add a buffer and that buffer would need a power supply... and that power supply could, in pinciple, be switchable. However if that were the case then I don't think the power supply for the buffer would belong in the bindings for the sy7758 so I'm afraid whichever way I turn it I can't make vddio-supply make sense. Daniel.
