On 27/10/2023 11:09, Wolfram Sang wrote: > On Fri, Oct 27, 2023 at 04:31:03PM +1300, Chris Packham wrote: >> Add bus-reset-gpios and bus-reset-duration-us properties to the >> marvell,mv64xxx-i2c binding. These can be used to describe hardware >> where a common reset GPIO is connected to all downstream devices on and >> I2C bus. This reset will be asserted then released before the downstream >> devices on the bus are probed. >> >> Signed-off-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx> >> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> > > Krzysztof, are you fine with this change? Actually no. NAK. Not because of the naming, but because the new name triggered some new paths in my brain which brought the point - this is old problem of power sequencing of children. I believe this must be solved in more generic way. First - generic for all I2C devices. Second - generic also matching other buses/subsystems, which have similar problem. We did it for USB (onboard USB), MMC (unloved MMC power sequence) and now we are doing it for PCIe and few others (Cc: Abel) https://lpc.events/event/17/contributions/1507/ Current solution is heavily limited. What about regulators? What about buses having 2 reset lines (still the same bus)? What about sequence? Best regards, Krzysztof
