On Thu, Jul 17, 2014 at 10:53:08AM +0200, Peter De Schrijver wrote: > On Wed, Jul 16, 2014 at 08:57:16PM +0200, Thierry Reding wrote: > > * PGP Signed by an unknown key > > > > On Wed, Jul 16, 2014 at 05:22:03PM +0200, Arnd Bergmann wrote: > > > On Wednesday 16 July 2014 17:14:29 Thierry Reding wrote: > > > > > > > > > > Ok, I'll have a look. I think when this becomes a separate driver, it > > > > > should also have its own header file, so maybe you can in the meantime > > > > > make it a local header file in mach-tegra until we have found a good > > > > > place for it. > > > > > > > > Why do you think it should be a separate header? We already have a > > > > couple in include/linux and I'm not sure it's useful to add even more. > > > > If anything I would've thought it made sense to move the content of the > > > > other headers into tegra-soc.h. > > > > > > I very much dislike the idea of having a per-vendor header file that > > > everything gets crammed into. We should try to have proper subsystems > > > and generic interfaces for these wherever possible. > > > > I completely agree. However spreading the SoC-specific functions across > > multiple header files isn't going to help. If we keep all the per-vendor > > APIs in one file it makes it easier to see what could still be moved off > > into a separate subsystem. > > > > Now for PMC specifically, we've investigated converting the powergate > > API to power domains. I don't think it will be possible to make that > > work. The issue is that there's a defined sequence that needs to be > > respected to make sure the device is powered up properly. That sequence > > involves the primary clock and reset of the device. It's been proposed > > to make these clocks available to the PMC driver so that it can control > > them, but then we can't make sure that clocks are really off if they > > need to be, since we have two drivers accessing them. The only way I see > > resets do not have reference counts, so they can be controlled by a > powerdomain driver without any problems. For clocks, there would only be > a problem for the module clocks if the drivers don't use runtime PM. If > we move all drivers to runtime PM, the clock control can move into the > powerdomain code and runtime PM will ensure domains are not turned off > with active modules. > > > to make that work reliably is by moving complete control of the > > powergate into drivers so that they can make sure clocks and resets are > > in the correct states. > > > > Which won't work if you have domains which contain several modules. We also need to control the memory clients in the domains using MC_CLIENT_HOTRESET_CTRL. Cheers, Peter. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
