drm/i915/display: stop using BUG()

Avoid bringing the entire machine down even if there's a bug that
shouldn't happen, but won't corrupt the system either. Log them loudly
and limp on.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220531162527.1062319-1-jani.nikula@intel.com

drivers/gpu/drm/i915/display/intel_ddi.c

@@ -455,6 +455,9 @@ intel_ddi_transcoder_func_reg_val_get(struct intel_encoder *encoder,
 		temp |= TRANS_DDI_SELECT_PORT(port);
 
 	switch (crtc_state->pipe_bpp) {
+	default:
+		MISSING_CASE(crtc_state->pipe_bpp);
+		fallthrough;
 	case 18:
 		temp |= TRANS_DDI_BPC_6;
 		break;
@@ -467,8 +470,6 @@ intel_ddi_transcoder_func_reg_val_get(struct intel_encoder *encoder,
 	case 36:
 		temp |= TRANS_DDI_BPC_12;
 		break;
-	default:
-		BUG();
 	}
 
 	if (crtc_state->hw.adjusted_mode.flags & DRM_MODE_FLAG_PVSYNC)
@@ -478,6 +479,9 @@ intel_ddi_transcoder_func_reg_val_get(struct intel_encoder *encoder,
 
 	if (cpu_transcoder == TRANSCODER_EDP) {
 		switch (pipe) {
+		default:
+			MISSING_CASE(pipe);
+			fallthrough;
 		case PIPE_A:
 			/* On Haswell, can only use the always-on power well for
 			 * eDP when not using the panel fitter, and when not
@@ -494,9 +498,6 @@ intel_ddi_transcoder_func_reg_val_get(struct intel_encoder *encoder,
 		case PIPE_C:
 			temp |= TRANS_DDI_EDP_INPUT_C_ONOFF;
 			break;
-		default:
-			BUG();
-			break;
 		}
 	}
 

drivers/gpu/drm/i915/display/intel_display.c

@@ -500,6 +500,9 @@ void vlv_wait_port_ready(struct drm_i915_private *dev_priv,
 	i915_reg_t dpll_reg;
 
 	switch (dig_port->base.port) {
+	default:
+		MISSING_CASE(dig_port->base.port);
+		fallthrough;
 	case PORT_B:
 		port_mask = DPLL_PORTB_READY_MASK;
 		dpll_reg = DPLL(0);
@@ -513,8 +516,6 @@ void vlv_wait_port_ready(struct drm_i915_private *dev_priv,
 		port_mask = DPLL_PORTD_READY_MASK;
 		dpll_reg = DPIO_PHY_STATUS;
 		break;
-	default:
-		BUG();
 	}
 
 	if (intel_de_wait_for_register(dev_priv, dpll_reg,
@@ -3159,6 +3160,10 @@ static void i9xx_set_pipeconf(const struct intel_crtc_state *crtc_state)
 				    PIPECONF_DITHER_TYPE_SP;
 
 		switch (crtc_state->pipe_bpp) {
+		default:
+			/* Case prevented by intel_choose_pipe_bpp_dither. */
+			MISSING_CASE(crtc_state->pipe_bpp);
+			fallthrough;
 		case 18:
 			pipeconf |= PIPECONF_BPC_6;
 			break;
@@ -3168,9 +3173,6 @@ static void i9xx_set_pipeconf(const struct intel_crtc_state *crtc_state)
 		case 30:
 			pipeconf |= PIPECONF_BPC_10;
 			break;
-		default:
-			/* Case prevented by intel_choose_pipe_bpp_dither. */
-			BUG();
 		}
 	}
 
@@ -3466,6 +3468,10 @@ static void ilk_set_pipeconf(const struct intel_crtc_state *crtc_state)
 	val = 0;
 
 	switch (crtc_state->pipe_bpp) {
+	default:
+		/* Case prevented by intel_choose_pipe_bpp_dither. */
+		MISSING_CASE(crtc_state->pipe_bpp);
+		fallthrough;
 	case 18:
 		val |= PIPECONF_BPC_6;
 		break;
@@ -3478,9 +3484,6 @@ static void ilk_set_pipeconf(const struct intel_crtc_state *crtc_state)
 	case 36:
 		val |= PIPECONF_BPC_12;
 		break;
-	default:
-		/* Case prevented by intel_choose_pipe_bpp_dither. */
-		BUG();
 	}
 
 	if (crtc_state->dither)

drivers/gpu/drm/i915/display/intel_display_types.h

@@ -1798,13 +1798,14 @@ static inline enum dpio_channel
 vlv_dig_port_to_channel(struct intel_digital_port *dig_port)
 {
 	switch (dig_port->base.port) {
+	default:
+		MISSING_CASE(dig_port->base.port);
+		fallthrough;
 	case PORT_B:
 	case PORT_D:
 		return DPIO_CH0;
 	case PORT_C:
 		return DPIO_CH1;
-	default:
-		BUG();
 	}
 }
 
@@ -1812,13 +1813,14 @@ static inline enum dpio_phy
 vlv_dig_port_to_phy(struct intel_digital_port *dig_port)
 {
 	switch (dig_port->base.port) {
+	default:
+		MISSING_CASE(dig_port->base.port);
+		fallthrough;
 	case PORT_B:
 	case PORT_C:
 		return DPIO_PHY0;
 	case PORT_D:
 		return DPIO_PHY1;
-	default:
-		BUG();
 	}
 }
 
@@ -1826,13 +1828,14 @@ static inline enum dpio_channel
 vlv_pipe_to_channel(enum pipe pipe)
 {
 	switch (pipe) {
+	default:
+		MISSING_CASE(pipe);
+		fallthrough;
 	case PIPE_A:
 	case PIPE_C:
 		return DPIO_CH0;
 	case PIPE_B:
 		return DPIO_CH1;
-	default:
-		BUG();
 	}
 }