linux-kernel - Re: [PATCH 6/9] ARM: tegra: Export tegra_powergate_power

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Date:	Thu, 19 Jun 2014 11:36:12 +0300
From:	Peter De Schrijver <pdeschrijver@...dia.com>
To:	Stephen Warren <swarren@...dotorg.org>
CC:	Thierry Reding <thierry.reding@...il.com>,
	Mikko Perttunen <mperttunen@...dia.com>,
	"tj@...nel.org" <tj@...nel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"linux-ide@...r.kernel.org" <linux-ide@...r.kernel.org>
Subject: Re: [PATCH 6/9] ARM: tegra: Export tegra_powergate_power_on

On Thu, Jun 19, 2014 at 10:02:35AM +0200, Peter De Schrijver wrote:
> On Wed, Jun 18, 2014 at 05:37:54PM +0200, Stephen Warren wrote:
> > On 06/18/2014 06:18 AM, Peter De Schrijver wrote:
> > > On Tue, Jun 17, 2014 at 11:51:20PM +0200, Thierry Reding wrote:
> > >> * PGP Signed by an unknown key
> > >>
> > >> On Tue, Jun 17, 2014 at 05:01:46PM +0300, Peter De Schrijver wrote:
> > >>> On Tue, Jun 17, 2014 at 02:13:15PM +0200, Thierry Reding wrote:
> > >>>>> Old Signed by an unknown key
> > >>>>
> > >>>> On Mon, Jun 16, 2014 at 04:01:02PM -0600, Stephen Warren wrote:
> > >>>>> On 06/04/2014 05:32 AM, Mikko Perttunen wrote:
> > >>>>>> This symbol needs to be exported to power on rails without using
> > >>>>>> tegra_powergate_sequence_power_up. tegra_powergate_sequence_power_up
> > >>>>>> cannot be used in situations where the driver wants to handle clocking
> > >>>>>> by itself.
> > >>>>>
> > >>>>> Thierry, are you OK with this change?
> > >>>>
> > >>>> I would've preferred tegra_powergate_sequence_power_up() to be used
> > >>>
> > >>> I don't think the current tegra_powergate_sequence_power_up() API is very well
> > >>> defined though. I don't think the clocks and resets required by the sequence
> > >>> should be provided by the driver. For one, there can be several clocks and
> > >>> resets that need to be controlled for a single domain.
> > >>
> > >> Do you have any suggestions for what the API should look like? Even if
> > >> we plan to move to some different API, I think there's some advantage in
> > >> using it consistently if for no other reason than to make it easier to
> > >> replace occurrences later on.
> > >>
> > > 
> > > I think the API should only have the domain ID as input so:
> > > 
> > > int tegra_powerdomain_on(int id) 
> > > 
> > > /*
> > >  * Prerequisites: domain is off
> > >  * Result: domain is on, clocks of the modules in the domain are off, modules are in reset
> > >  */
> > > 
> > > int tegra_powerdomain_off(int id)
> > > 
> > > /*
> > >  * Prerequisites: all clocks of the modules in the domain are off
> > >  * result: domain is off
> > >  */
> > 
> > That doesn't make sense; the PMC doesn't have access to the clock and
> > reset IDs - that's why the API requires them to be passed in.
> > 
> 
> We should make driver look them up by name then. It doesn't make sense to

I mean the PMC driver here.
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