Re: [Intel-gfx] [PATCH 3/4] drm/i915/dsi/xelpd: Disable DC states in Video mode

[Imre Deak <imre.deak@intel.com>]

On Tue, Oct 19, 2021 at 01:24:51PM +0300, Jani Nikula wrote:
> On Mon, 18 Oct 2021, Vandita Kulkarni <vandita.kulkarni@intel.com> wrote:
> > MIPI DSI transcoder cannot be in video mode to support any of the
> > display C states.
> 
> Imre, could you review this one please?
> 
> The added confusion is that POWER_DOMAIN_TRANSCODER_DSI_A and
> POWER_DOMAIN_TRANSCODER_DSI_C are never used anywhere and
> POWER_DOMAIN_TRANSCODER() does not take DSI transcoders into account.

<tl;dr>
You mean they are not listed in the power_domain->power_well mappings.
Those power domains don't use any power wells above PW#1. PW#0/1 is
handled "automatically" by DMC, so we don't have to toggle the power for
those manually. However they still need a runtime PM reference, since
whatever HW domain you want to use, the PCI device must be in the runtime
resumed state. This is ensured by the always-on power well, which every
domain has a dependency on.
<tl;dr>

The transcoder power domains are acquired in get_crtc_power_domains(),
doesn't the DSI encoder using the DSI_A/C transcoders?

Yes, POWER_DOMAIN_TRANSCODER is now broken wrt. DSI due to
POWER_DOMAIN_TRANSCODER_VDSC_PW2. So that would need to be moved after
the TRANSCODER_DSI_C. And the POWER_DOMAIN_TRANSCODER macro could be
also simplified afaics.

Otherwise this patch looks ok to me, just the bspec links would be good
to have here too.

> 
> > Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display_power.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
> > index 709569211c85..8406db5e573e 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_power.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display_power.c
> > @@ -3105,7 +3105,8 @@ intel_display_power_put_mask_in_set(struct drm_i915_private *i915,
> >  	BIT_ULL(POWER_DOMAIN_MODESET) |			\
> >  	BIT_ULL(POWER_DOMAIN_AUX_A) |			\
> >  	BIT_ULL(POWER_DOMAIN_AUX_B) |			\
> > -	BIT_ULL(POWER_DOMAIN_INIT))
> > +	BIT_ULL(POWER_DOMAIN_INIT)) |			\
> > +	BIT_ULL(POWER_DOMAIN_PORT_DSI)
> 
> Everywhere else POWER_DOMAIN_INIT is last in the list.
> 
> BR,
> Jani.
> 
> >  
> >  #define XELPD_AUX_IO_D_XELPD_POWER_DOMAINS	BIT_ULL(POWER_DOMAIN_AUX_D_XELPD)
> >  #define XELPD_AUX_IO_E_XELPD_POWER_DOMAINS	BIT_ULL(POWER_DOMAIN_AUX_E_XELPD)
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center