[Intel-gfx] [PATCH 2/2] drm/i915/skl: Implementation of SKL display power well support

[Damien Lespiau]

On Wed, Feb 04, 2015 at 04:20:28PM +0200, Imre Deak wrote:
> On ke, 2015-02-04 at 13:53 +0000, Damien Lespiau wrote:
> > On Tue, Feb 03, 2015 at 01:06:31AM +0200, Imre Deak wrote:
> > > > +static struct i915_power_well skl_power_wells[] = {
> > > > +	{
> > > > +		.name = "always-on",
> > > > +		.always_on = 1,
> > > > +		.domains = SKL_DISPLAY_ALWAYS_ON_POWER_DOMAINS,
> > > > +		.ops = &i9xx_always_on_power_well_ops,
> > > > +	},
> > > > +	{
> > > > +		.name = "power well 1",
> > > > +		.domains = SKL_DISPLAY_POWERWELL_1_POWER_DOMAINS,
> > > > +		.ops = &skl_power_well_ops,
> > > > +		.data = SKL_DISP_PW_1,
> > > > +	},
> > 
> > snip
> > 
> > > > +	{
> > > > +		.name = "MISC IO power well",
> > > > +		.domains = SKL_DISPLAY_MISC_IO_POWER_DOMAINS,
> > > > +		.ops = &skl_power_well_ops,
> > > > +		.data = SKL_DISP_PW_MISC_IO,
> > > > +	}
> > > 
> > > Again, since the recent bspec change the misc IO power well should be
> > > enabled before anything else, so it needs to be listed before "power
> > > well 1" on the list.
> > 
> > So this one was causing problems. When I try to enabled MISC IO before
> > PW1, the request times out. Enabling MISC IO just right after PW1 seems
> > to work fine though.
> 
> Ok. Bspec doesn't say anything about the ordering between PW1 and MISC
> IO, just that you have to enable them together and wait for PG1 fuse
> afterwards. How about then moving the MISC IO power well right after PW1
> in the list and wait for the PG1 fuse after enabling MISC IO?
 
I think we can even set the 2 requests in the same write and it should
do the right thing (and so merge the two power wells). That's really a
detail though and as the current code it seems to work, I'll leave such
refinements for later/if needed.

-- 
Damien