Hi, On Fri, Jul 7, 2023 at 3:32 AM Doug Anderson <dianders@xxxxxxxxxx> wrote: > > Hi, > > On Mon, Jul 3, 2023 at 10:07 PM Cong Yang > <yangcong5@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > From power on/off sequence for panel data sheet[1], T2 timing VSP to VSN > > needs 1ms delay when power on, and VSN to VSP also needs 1ms delay when > > power off. Some pmic may not be able to adjust the delay internally, so > > let's add a delay between avdd/avee regulator gpio to meet the timing of > > panel. > > Unless I'm mistaken, all of this is best handled via regulator > constraints in the device tree. See the file: > > Documentation/devicetree/bindings/regulator/regulator.yaml > > Specifically, any delays related to actually ramping up / down the > regulator can be specified in the device tree. Nominally, you could > argue that the 1 ms delay actually _does_ belong in the driver, but > IMO the 1 ms number there is really just there because someone thought > it was weird to specify a delay of 0 ms. Given that you already need > remp delays in the device tree, it feels OK to me to just include the > 1 ms there. The regulator device tree has only the power on attribute "regulator-enable-ramp-delay", not has power off attribute. The regulator delay looks more like the HW voltage requirement of the power ic itself, and I just want to meet the panel spec requirement. I add regulator-enable-ramp-delay in dts he can also meet my requirement, but I have no way to control the power off delays. Thanks Doug. > > -Doug
