+Jens W On Thu, Mar 7, 2019 at 6:22 AM Aisheng Dong <aisheng.dong@xxxxxxx> wrote: > > Hi Rob, > > > > > I think Rob suggested that the SCU parent driver should instantiate > > > > the watchdog without explicit watchdog node. That would be possible, > > > > but it currently uses > > > > devm_of_platform_populate() to do the instantiation, and changing > > > > that would be a mess. Besides, it does sem to me that your suggested > > > > node would describe the hardware, so I am not sure I understand the > > reasoning. > > > > It would just be a call to create a platform device instead. How is that a mess? > > > > It's describing firmware. We have DT for describing h/w we've failed to make > > discoverable. We should not repeat that and just describe firmware in DT. > > Make the firmware discoverable! Though there are cases like firmware > > provided clocks where we still need something in DT, but this is not one of > > them. > > > > The watchdog node here in question actually is not using SCU firmware call. > Due to security requirement by SCU, watchdog can only be accessed in > security mode, for IMX case, via ARM Trust Firmware. That means the > watchdog used in Linux actually is using ARM SMC call and does not > depend SCU driver. So It would be strange for SCU driver to instantiate it. > > For this situation, do you think we can move watchdog out of scu node? > Maybe rename the compatible string like "fsl,imx8qxp-sip-watchdog" > because it's actually a watchdog serviced by ATF firmware. Yes, but that creates more questions. What exactly does ATF talk to for the watchdog? The SCU firmware? Maybe ATF should define and provide a standard watchdog interface? It is still a question of making the firmware discoverable rather than trying to describe the firmware in DT. Rob
