[Intel-gfx] [PATCH] drm/i915: Tolerate bogus DPLL selection

[Karthik B S]

On 3/11/2021 1:13 AM, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Let's check that we actually found the PLL before doing the
> port_clock readout, just in case the hardware is severly
> misprogramming by the previous guy. Not sure the hw would
> even survive such misprogramming without hanging but no
> real harm in checking anyway.
>
> Cc: Karthik B S <karthik.b.s at intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Looks good to me.

Reviewed-by: Karthik B S <karthik.b.s at intel.com>

> ---
>   drivers/gpu/drm/i915/display/intel_ddi.c | 17 +++++++++++++----
>   1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index ba83682e1d3e..64a952db8528 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -3716,6 +3716,9 @@ void intel_ddi_get_clock(struct intel_encoder *encoder,
>   	struct icl_port_dpll *port_dpll = &crtc_state->icl_port_dplls[port_dpll_id];
>   	bool pll_active;
>   
> +	if (drm_WARN_ON(&i915->drm, !pll))
> +		return;
> +
>   	port_dpll->pll = pll;
>   	pll_active = intel_dpll_get_hw_state(i915, pll, &port_dpll->hw_state);
>   	drm_WARN_ON(&i915->drm, !pll_active);
> @@ -3754,16 +3757,17 @@ static void icl_ddi_combo_get_config(struct intel_encoder *encoder,
>   	intel_ddi_get_config(encoder, crtc_state);
>   }
>   
> -static void icl_ddi_tc_get_config(struct intel_encoder *encoder,
> -				  struct intel_crtc_state *crtc_state)
> +static void icl_ddi_tc_get_clock(struct intel_encoder *encoder,
> +				 struct intel_crtc_state *crtc_state,
> +				 struct intel_shared_dpll *pll)
>   {
>   	struct drm_i915_private *i915 = to_i915(encoder->base.dev);
>   	enum icl_port_dpll_id port_dpll_id;
>   	struct icl_port_dpll *port_dpll;
> -	struct intel_shared_dpll *pll;
>   	bool pll_active;
>   
> -	pll = icl_ddi_tc_get_pll(encoder);
> +	if (drm_WARN_ON(&i915->drm, !pll))
> +		return;
>   
>   	if (intel_get_shared_dpll_id(i915, pll) == DPLL_ID_ICL_TBTPLL)
>   		port_dpll_id = ICL_PORT_DPLL_DEFAULT;
> @@ -3783,7 +3787,12 @@ static void icl_ddi_tc_get_config(struct intel_encoder *encoder,
>   	else
>   		crtc_state->port_clock = intel_dpll_get_freq(i915, crtc_state->shared_dpll,
>   							     &crtc_state->dpll_hw_state);
> +}
>   
> +static void icl_ddi_tc_get_config(struct intel_encoder *encoder,
> +				  struct intel_crtc_state *crtc_state)
> +{
> +	icl_ddi_tc_get_clock(encoder, crtc_state, icl_ddi_tc_get_pll(encoder));
>   	intel_ddi_get_config(encoder, crtc_state);
>   }
>