[PATCH] drm/i915: Try to preserve the current shared_dpll for fastset on type-c ports

[Kandpal, Suraj]

> Subject: [PATCH] drm/i915: Try to preserve the current shared_dpll for fastset
> on type-c ports
> 
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Currently icl_compute_tc_phy_dplls() assumes that the active PLL will be the
> TC PLL (as opposed to the TBT PLL). The actual PLL will be selected during the
> modeset enable sequence, but we need to put *something* into the
> crtc_state->shared_dpll already during compute_config().
> 
> The downside of assuming one PLL or the other is that we'll fail to fastset if the
> assumption doesn't match what was in use previously. So let's instead keep
> the same PLL that was in use previously (assuming there was one). This should
> allow fastset to work again when using TBT PLL, at least in the steady state.
> 
> Now, assuming we want keep the same PLL may not be entirely correct either.
> But we should be covered by the typ-c link reset handling which will force a full

Small typo *type-c

> modeset by flagging connectors_changed=true which means the resulting
> modeset can't be converted into a fastset even if the full crtc state looks
> identical.
> 
> Cc: Imre Deak <imre.deak at intel.com>
> Cc: Suraj Kandpal <suraj.kandpal at intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

LGTM.
Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_dpll_mgr.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
> b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
> index ef57dad1a9cb..1008e18177c9 100644
> --- a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
> +++ b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
> @@ -3308,6 +3308,8 @@ static int icl_compute_tc_phy_dplls(struct
> intel_atomic_state *state,
>  	struct drm_i915_private *i915 = to_i915(state->base.dev);
>  	struct intel_crtc_state *crtc_state =
>  		intel_atomic_get_new_crtc_state(state, crtc);
> +	const struct intel_crtc_state *old_crtc_state =
> +		intel_atomic_get_old_crtc_state(state, crtc);
>  	struct icl_port_dpll *port_dpll =
>  		&crtc_state->icl_port_dplls[ICL_PORT_DPLL_DEFAULT];
>  	struct skl_wrpll_params pll_params = {}; @@ -3326,7 +3328,11 @@
> static int icl_compute_tc_phy_dplls(struct intel_atomic_state *state,
>  		return ret;
> 
>  	/* this is mainly for the fastset check */
> -	icl_set_active_port_dpll(crtc_state, ICL_PORT_DPLL_MG_PHY);
> +	if (old_crtc_state->shared_dpll &&
> +	    old_crtc_state->shared_dpll->info->id == DPLL_ID_ICL_TBTPLL)
> +		icl_set_active_port_dpll(crtc_state, ICL_PORT_DPLL_DEFAULT);
> +	else
> +		icl_set_active_port_dpll(crtc_state,
> ICL_PORT_DPLL_MG_PHY);
> 
>  	crtc_state->port_clock = icl_ddi_mg_pll_get_freq(i915, NULL,
>  							 &port_dpll-
> >hw_state);
> --
> 2.41.0