[Intel-gfx] [V2 3/4] drm/i915/dsi/xelpd: Disable DC states in Video mode

[Kulkarni, Vandita]

> -----Original Message-----
> From: Deak, Imre <imre.deak at intel.com>
> Sent: Saturday, October 23, 2021 1:53 AM
> To: Kulkarni, Vandita <vandita.kulkarni at intel.com>
> Cc: intel-gfx at lists.freedesktop.org; Nikula, Jani <jani.nikula at intel.com>;
> Roper, Matthew D <matthew.d.roper at intel.com>;
> ville.syrjala at linux.intel.com
> Subject: Re: [V2 3/4] drm/i915/dsi/xelpd: Disable DC states in Video mode
> 
> On Tue, Oct 19, 2021 at 08:44:34PM +0530, Vandita Kulkarni wrote:
> > MIPI DSI transcoder cannot be in video mode to support any of the
> > display C states.
> >
> > Bspec: 49195 (For DC*co DSI transcoders cannot be in video mode)
> > Bspec: 49193 (Hardware does not support DC5 or DC6 with MIPI DSI
> > enabled)
> > Bspec: 49188 (desc of DSI_DCSTATE_CTL talks about cmd mode PM control
> 
> So none of the DC states (except DC6v which the driver doesn't support) are
> supported in DSI video mode and DC3co is supported in command mode.
> The selection between video vs. command mode happens using a VBT flag
> and I can't see anything that would prevent using command mode on XELPD.
> If the support for it is missing, should it be disabled explicitly or at least a
> notice printed that DC states are not yet supported?

Since we haven't enabled and tried dsi cmd mode on xelpd and in DC3co DMC
Would monitor the idleness of the transcoder, until that is enabled, we can disable
Cmd mode for now.
Will send out a patch to disable cmd mode on xelpd, as it would by default depend on
Vbt like you have mentioned above.

Thanks,
Vandita
 
> 
> > v2: Align to the power domain ordering (Jani)
> >     Add bspec references (Imre)
> >
> > Signed-off-by: Vandita Kulkarni <vandita.kulkarni at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display_power.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c
> > b/drivers/gpu/drm/i915/display/intel_display_power.c
> > index d88da0d0f05a..b989ddd3d023 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_power.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display_power.c
> > @@ -3106,6 +3106,7 @@ 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_PORT_DSI) |		\
> >  	BIT_ULL(POWER_DOMAIN_INIT))
> >
> >  #define XELPD_AUX_IO_D_XELPD_POWER_DOMAINS
> 	BIT_ULL(POWER_DOMAIN_AUX_D_XELPD)
> > --
> > 2.32.0
> >