[PATCH 1/6] drm/i915: Warn if a pipe is enabled with a bogus port

[Damien Lespiau <damien.lespiau@intel.com>]

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.lespiau@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