drm/i915/ddi: Add more sanity check to the encoder HW readout

Check for reserved register field values and conflicting
transcoder->port mappings (both MST and non-MST mappings or multiple SST
mappings).

This is also needed for the next patch to determine if a port is in MST
mode during sanitization after HW readout.

Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Antonio Argenziano <antonio.argenziano@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Clint Taylor <Clinton.A.Taylor@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181107200836.10191-1-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index ab9a36c..abc5169 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -2005,24 +2005,24 @@ out:
        return ret;
 }
 
-bool intel_ddi_get_hw_state(struct intel_encoder *encoder,
-                           enum pipe *pipe)
+static void intel_ddi_get_encoder_pipes(struct intel_encoder *encoder,
+                                       u8 *pipe_mask, bool *is_dp_mst)
 {
        struct drm_device *dev = encoder->base.dev;
        struct drm_i915_private *dev_priv = to_i915(dev);
        enum port port = encoder->port;
        enum pipe p;
        u32 tmp;
-       bool ret;
+       u8 mst_pipe_mask;
+
+       *pipe_mask = 0;
+       *is_dp_mst = false;
 
        if (!intel_display_power_get_if_enabled(dev_priv,
                                                encoder->power_domain))
-               return false;
-
-       ret = false;
+               return;
 
        tmp = I915_READ(DDI_BUF_CTL(port));
-
        if (!(tmp & DDI_BUF_CTL_ENABLE))
                goto out;
 
@@ -2030,44 +2030,58 @@ bool intel_ddi_get_hw_state(struct intel_encoder *encoder,
                tmp = I915_READ(TRANS_DDI_FUNC_CTL(TRANSCODER_EDP));
 
                switch (tmp & TRANS_DDI_EDP_INPUT_MASK) {
+               default:
+                       MISSING_CASE(tmp & TRANS_DDI_EDP_INPUT_MASK);
+                       /* fallthrough */
                case TRANS_DDI_EDP_INPUT_A_ON:
                case TRANS_DDI_EDP_INPUT_A_ONOFF:
-                       *pipe = PIPE_A;
+                       *pipe_mask = BIT(PIPE_A);
                        break;
                case TRANS_DDI_EDP_INPUT_B_ONOFF:
-                       *pipe = PIPE_B;
+                       *pipe_mask = BIT(PIPE_B);
                        break;
                case TRANS_DDI_EDP_INPUT_C_ONOFF:
-                       *pipe = PIPE_C;
+                       *pipe_mask = BIT(PIPE_C);
                        break;
                }
 
-               ret = true;
-
                goto out;
        }
 
+       mst_pipe_mask = 0;
        for_each_pipe(dev_priv, p) {
-               enum transcoder cpu_transcoder = (enum transcoder) p;
+               enum transcoder cpu_transcoder = (enum transcoder)p;
 
                tmp = I915_READ(TRANS_DDI_FUNC_CTL(cpu_transcoder));
 
-               if ((tmp & TRANS_DDI_PORT_MASK) == TRANS_DDI_SELECT_PORT(port)) {
-                       if ((tmp & TRANS_DDI_MODE_SELECT_MASK) ==
-                           TRANS_DDI_MODE_SELECT_DP_MST)
-                               goto out;
+               if ((tmp & TRANS_DDI_PORT_MASK) != TRANS_DDI_SELECT_PORT(port))
+                       continue;
 
-                       *pipe = p;
-                       ret = true;
+               if ((tmp & TRANS_DDI_MODE_SELECT_MASK) ==
+                   TRANS_DDI_MODE_SELECT_DP_MST)
+                       mst_pipe_mask |= BIT(p);
 
-                       goto out;
-               }
+               *pipe_mask |= BIT(p);
        }
 
-       DRM_DEBUG_KMS("No pipe for ddi port %c found\n", port_name(port));
+       if (!*pipe_mask)
+               DRM_DEBUG_KMS("No pipe for ddi port %c found\n",
+                             port_name(port));
+
+       if (!mst_pipe_mask && hweight8(*pipe_mask) > 1) {
+               DRM_DEBUG_KMS("Multiple pipes for non DP-MST port %c (pipe_mask %02x)\n",
+                             port_name(port), *pipe_mask);
+               *pipe_mask = BIT(ffs(*pipe_mask) - 1);
+       }
+
+       if (mst_pipe_mask && mst_pipe_mask != *pipe_mask)
+               DRM_DEBUG_KMS("Conflicting MST and non-MST encoders for port %c (pipe_mask %02x mst_pipe_mask %02x)\n",
+                             port_name(port), *pipe_mask, mst_pipe_mask);
+       else
+               *is_dp_mst = mst_pipe_mask;
 
 out:
-       if (ret && IS_GEN9_LP(dev_priv)) {
+       if (*pipe_mask && IS_GEN9_LP(dev_priv)) {
                tmp = I915_READ(BXT_PHY_CTL(port));
                if ((tmp & (BXT_PHY_CMNLANE_POWERDOWN_ACK |
                            BXT_PHY_LANE_POWERDOWN_ACK |
@@ -2077,8 +2091,22 @@ out:
        }
 
        intel_display_power_put(dev_priv, encoder->power_domain);
+}
 
-       return ret;
+bool intel_ddi_get_hw_state(struct intel_encoder *encoder,
+                           enum pipe *pipe)
+{
+       u8 pipe_mask;
+       bool is_mst;
+
+       intel_ddi_get_encoder_pipes(encoder, &pipe_mask, &is_mst);
+
+       if (is_mst || !pipe_mask)
+               return false;
+
+       *pipe = ffs(pipe_mask) - 1;
+
+       return true;
 }
 
 static inline enum intel_display_power_domain