On Thu, Mar 18, 2010 at 09:57:06AM -0700, Kevin Hilman wrote: > Greg KH <gregkh@xxxxxxx> writes: > > > On Wed, Mar 17, 2010 at 04:18:15PM -0700, Kevin Hilman wrote: > >> When runtime PM for platform_bus was added, it allowed for platforms > >> to customize the runtime PM methods since they are defined as weak > >> symbols. > >> > >> This patch allows platforms to also extend the system PM methods with > >> custom hooks so runtime PM and system PM extensions can be managed > >> together by custom platform-specific code. > > > > Wow, that's scary, I didn't realize that was done for the runtime stuff. > > > > What would you be replacing these functions with for your platform that > > would require it to be in arch-specific code? > > I'm basically copying the existing functions and extending them with > platform-specific code to manage device clocks and other PM HW state. > IOW, I still call the drivers PM methods, but also take care of some > platform specific PM HW management. This is just like the runtime PM > hooks: platform-specific code + calling drivers runtime PM methods. > > On my platform (TI OMAP), the code to handle device PM is common for > all devices, so for runtime PM, I'm taking care of it at the bus > level. At the hardware level, there's really no difference between > runtime and system PM, so I want to take advantage of the same > platform specific code for system PM > > Initially, rather than making the system PM methods themselves weak, I > added some weak hooks that could be overridden instead (see test patch > below). The problem with that is that it is not as flexible if you > want to run some custom code before and/or after calling the drivers > PM methods. To be more flexible, using this approach, we'd probably > need pre- and post- hooks to be used before and after the driver's PM > methods are called. Rather than add all these hooks, I decided it was > cleaner to just allow override of the primary methods themselves, > which parallels the runtime PM approach. Ok, that sounds reasonable for now. I'll queue it up for .35. thanks, greg k-h _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
