On Mon, Jul 21, 2014 at 03:09:29PM +0800, Vince Hsu wrote: > > On 07/17/2014 07:01 PM, Thierry Reding wrote: > >* PGP Signed by an unknown key > > > >On Thu, Jul 17, 2014 at 12:01:56PM +0300, Peter De Schrijver wrote: > >>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: > >>>>>Old 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. > >Oh, great. More interdependencies... > Some domains depend on others. Can we take this into account? I'm not aware of any dependencies. Can you point me at the relevant section in the TRM? Thierry
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