Nouveau - Jan 2015 - [PATCH 1/11] ARM: tegra: add function to control the GPU rail clamp

On Wed, Jan 07, 2015 at 10:28:29PM +0800, Vince Hsu
wrote:
> On 04:08:52PM Jan 07, Peter De Schrijver wrote:
> > On Wed, Jan 07, 2015 at 02:27:10PM +0100, Thierry Reding wrote:
> > 
> > > > Yeah. I plan to have the information of all the clock client
of the
> > > > partitions and
> > > > the memory clients be defined statically in c source, e.g.
pmc-tegra124.c.
> > > > All modules can declare which domain they belong to in DT.
One domain can
> > > > be really power gated only when no module is awake. Note the
clock clients
> > > > of
> > > > one domain might not equal to the clocks of the module. The
reset is not
> > > > either.
> > > > So I don't get the clock and reset from module. How do
you think?
> > > 
> > > This whole situation is quite messy. The above sequence basically
means
> > > that drivers can't reset hardware modules because otherwise
they might
> > > race with the power domain code. It also means that we can't
powergate
> > 
> > The powerdomain framework won't call any powergating method as
long as a
> > module in the domain is still active. So as long as drivers don't
try to
> > reset the hw without having done a pm_runtime_get(), we shouldn't
have such
> > a race?
> Agree. And as long as the driver has the correct reset procedure, that
should
> be fine to occur between power ungating and gating sequences.
> 
> > 
> > > modules on demand because they might be in the same power domain
as one
> > > other module that's still busy.
> > > 
> > 
> > The powerdomain framework keeps track of which modules are active (by
hooking
> > into runtime pm) and won't try to shutdown a domain unless all
modules are
> > inactive.
> Yeah. By the way, that means we should start supporting runtime pm for all
> the modules to use generic power domain.
Indeed, that'll be a prerequisite before we can merge power domain
support. I do have a couple of local patches that add very rudimentary
runtime PM for various drivers. For starters we could probably just do
the

	pm_runtime_enable(...);
	pm_runtime_get_sync(...)

in the ->probe() and

	pm_runtime_put_sync(...);
	pm_runtime_disable(...);

in the ->remove() callbacks for those drivers. That's by no means
optimal but should get us pretty close to what we do now and still
support the generic power domains.

Thierry
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On 01/07/2015 10:48 PM, Thierry Reding wrote:
> * PGP Signed by an unknown key
>
> On Wed, Jan 07, 2015 at 10:28:29PM +0800, Vince Hsu wrote:
>> On 04:08:52PM Jan 07, Peter De Schrijver wrote:
>>> On Wed, Jan 07, 2015 at 02:27:10PM +0100, Thierry Reding wrote:
>>>
>>>>> Yeah. I plan to have the information of all the clock
client of the
>>>>> partitions and
>>>>> the memory clients be defined statically in c source, e.g.
pmc-tegra124.c.
>>>>> All modules can declare which domain they belong to in DT.
One domain can
>>>>> be really power gated only when no module is awake. Note
the clock clients
>>>>> of
>>>>> one domain might not equal to the clocks of the module. The
reset is not
>>>>> either.
>>>>> So I don't get the clock and reset from module. How do
you think?
>>>> This whole situation is quite messy. The above sequence
basically means
>>>> that drivers can't reset hardware modules because otherwise
they might
>>>> race with the power domain code. It also means that we
can't powergate
>>> The powerdomain framework won't call any powergating method as
long as a
>>> module in the domain is still active. So as long as drivers
don't try to
>>> reset the hw without having done a pm_runtime_get(), we
shouldn't have such
>>> a race?
>> Agree. And as long as the driver has the correct reset procedure, that
should
>> be fine to occur between power ungating and gating sequences.
>>
>>>> modules on demand because they might be in the same power
domain as one
>>>> other module that's still busy.
>>>>
>>> The powerdomain framework keeps track of which modules are active
(by hooking
>>> into runtime pm) and won't try to shutdown a domain unless all
modules are
>>> inactive.
>> Yeah. By the way, that means we should start supporting runtime pm for
all
>> the modules to use generic power domain.
> Indeed, that'll be a prerequisite before we can merge power domain
> support. I do have a couple of local patches that add very rudimentary
> runtime PM for various drivers. For starters we could probably just do
> the
>
> 	pm_runtime_enable(...);
> 	pm_runtime_get_sync(...)
>
> in the ->probe() and
>
> 	pm_runtime_put_sync(...);
> 	pm_runtime_disable(...);
>
> in the ->remove() callbacks for those drivers. That's by no means
> optimal but should get us pretty close to what we do now and still
> support the generic power domains.
Cool. Could you send me the patches?

Thanks,
Vince
>
> Thierry
>
> * Unknown Key
> * 0x7F3EB3A1

On Thu, Jan 08, 2015 at 12:25:18PM +0800, Vince Hsu
wrote:
> 
> On 01/07/2015 10:48 PM, Thierry Reding wrote:
> >* PGP Signed by an unknown key
> >
> >On Wed, Jan 07, 2015 at 10:28:29PM +0800, Vince Hsu wrote:
> >>On 04:08:52PM Jan 07, Peter De Schrijver wrote:
> >>>On Wed, Jan 07, 2015 at 02:27:10PM +0100, Thierry Reding wrote:
> >>>
> >>>>>Yeah. I plan to have the information of all the clock
client of the
> >>>>>partitions and
> >>>>>the memory clients be defined statically in c source,
e.g. pmc-tegra124.c.
> >>>>>All modules can declare which domain they belong to in
DT. One domain can
> >>>>>be really power gated only when no module is awake.
Note the clock clients
> >>>>>of
> >>>>>one domain might not equal to the clocks of the module.
The reset is not
> >>>>>either.
> >>>>>So I don't get the clock and reset from module. How
do you think?
> >>>>This whole situation is quite messy. The above sequence
basically means
> >>>>that drivers can't reset hardware modules because
otherwise they might
> >>>>race with the power domain code. It also means that we
can't powergate
> >>>The powerdomain framework won't call any powergating method
as long as a
> >>>module in the domain is still active. So as long as drivers
don't try to
> >>>reset the hw without having done a pm_runtime_get(), we
shouldn't have such
> >>>a race?
> >>Agree. And as long as the driver has the correct reset procedure,
that should
> >>be fine to occur between power ungating and gating sequences.
> >>
> >>>>modules on demand because they might be in the same power
domain as one
> >>>>other module that's still busy.
> >>>>
> >>>The powerdomain framework keeps track of which modules are
active (by hooking
> >>>into runtime pm) and won't try to shutdown a domain unless
all modules are
> >>>inactive.
> >>Yeah. By the way, that means we should start supporting runtime pm
for all
> >>the modules to use generic power domain.
> >Indeed, that'll be a prerequisite before we can merge power domain
> >support. I do have a couple of local patches that add very rudimentary
> >runtime PM for various drivers. For starters we could probably just do
> >the
> >
> >	pm_runtime_enable(...);
> >	pm_runtime_get_sync(...)
> >
> >in the ->probe() and
> >
> >	pm_runtime_put_sync(...);
> >	pm_runtime_disable(...);
> >
> >in the ->remove() callbacks for those drivers. That's by no
means
> >optimal but should get us pretty close to what we do now and still
> >support the generic power domains.
> Cool. Could you send me the patches?
Here are two examples:

	https://github.com/thierryreding/linux/commit/36b5c34f68edb8135b9afb3e62c7ce9a527d6793
	https://github.com/thierryreding/linux/commit/6a6145d9e0fcbd4f9599552181fc02f4606b6a0e

Thierry
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