On Tue, Mar 17, 2009 at 11:15:06AM -0700, David Brownell wrote: > On Monday 16 March 2009, Mark Brown wrote: > > Devices that need to do things like set voltages are fairly likely to > > own the regulator but with devices that just need to ensure that they > > have their supplies enabled it's much more likely that the supplies will > > be shared. > Right. Do you have a model how such shared supplies would > coexist with the "enabled at boot time" model, and still > support being disabled? The drivers can essentially ignore the physical status of the regulator when they start, enabling when they need them and disabling when they're done. So long as at least one device has the regulator enabled the regulator will remain on but when the reference count drops to zero then the regulator will be disabled. This works well when the driver will be enabling the regulators at startup and then disabling them later on. It will also work well with a late_initcall which disables any unreferenced regulators - that should become the default at some future point (2.6.31 might be a good candiate here, I posted a patch the other day providing an implementation which warns if there are affected regulators and which machines can activate if they want). > My first thought is that the system designer should avoid > such boot_on modes. But that's not always going to work. Yes, that's not something that can realistically be achieved in the general case. Machines should probably avoid it but often people want to do things like bring LCDs up in the bootloader and providing graceful handover to the actual driver helps the user experience. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
