If TRANS_DDI_FUNC_CTL has been wrongly programmed with an incorrect
port, we are currently trying to read PORT_CLK_SEL(port) with an
initialized value.

Handle that case by returning PORT_CLK_SEL_NONE and warning about it.

Signed-off-by: Damien Lespiau <damien.lesp...@intel.com>

to add to first
---
 drivers/gpu/drm/i915/intel_ddi.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 56bb7cb..3b5838d 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1157,7 +1157,7 @@ static uint32_t intel_ddi_get_crtc_pll(struct 
drm_i915_private *dev_priv,
                                       enum pipe pipe)
 {
        uint32_t temp, ret;
-       enum port port;
+       enum port port = I915_MAX_PORTS;
        enum transcoder cpu_transcoder = intel_pipe_to_cpu_transcoder(dev_priv,
                                                                      pipe);
        int i;
@@ -1173,7 +1173,10 @@ static uint32_t intel_ddi_get_crtc_pll(struct 
drm_i915_private *dev_priv,
                                port = i;
        }
 
-       ret = I915_READ(PORT_CLK_SEL(port));
+       if (port == I915_MAX_PORTS)
+               ret = PORT_CLK_SEL_NONE;
+       else
+               ret = I915_READ(PORT_CLK_SEL(port));
 
        DRM_DEBUG_KMS("Pipe %c connected to port %c using clock 0x%08x\n",
                      pipe_name(pipe), port_name(port), ret);
@@ -1207,6 +1210,10 @@ void intel_ddi_setup_hw_pll_state(struct drm_device *dev)
                case PORT_CLK_SEL_WRPLL2:
                        dev_priv->ddi_plls.wrpll2_refcount++;
                        break;
+               case PORT_CLK_SEL_NONE:
+                       WARN(1, "Pipe %c enabled but no clock selected\n",
+                            pipe_name(pipe));
+                       break;
                }
        }
 }
-- 
1.7.7.5

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