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-rw-r--r--drivers/gpu/drm/i915/intel_sdvo.c40
1 files changed, 39 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
index 62d22ae4a1d1..e3b7a7ee39cb 100644
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -1929,6 +1929,41 @@ static const struct drm_encoder_funcs intel_sdvo_enc_funcs = {
.destroy = intel_sdvo_enc_destroy,
};
+static void
+intel_sdvo_guess_ddc_bus(struct intel_sdvo *sdvo)
+{
+ uint16_t mask = 0;
+ unsigned int num_bits;
+
+ /* Make a mask of outputs less than or equal to our own priority in the
+ * list.
+ */
+ switch (sdvo->controlled_output) {
+ case SDVO_OUTPUT_LVDS1:
+ mask |= SDVO_OUTPUT_LVDS1;
+ case SDVO_OUTPUT_LVDS0:
+ mask |= SDVO_OUTPUT_LVDS0;
+ case SDVO_OUTPUT_TMDS1:
+ mask |= SDVO_OUTPUT_TMDS1;
+ case SDVO_OUTPUT_TMDS0:
+ mask |= SDVO_OUTPUT_TMDS0;
+ case SDVO_OUTPUT_RGB1:
+ mask |= SDVO_OUTPUT_RGB1;
+ case SDVO_OUTPUT_RGB0:
+ mask |= SDVO_OUTPUT_RGB0;
+ break;
+ }
+
+ /* Count bits to find what number we are in the priority list. */
+ mask &= sdvo->caps.output_flags;
+ num_bits = hweight16(mask);
+ /* If more than 3 outputs, default to DDC bus 3 for now. */
+ if (num_bits > 3)
+ num_bits = 3;
+
+ /* Corresponds to SDVO_CONTROL_BUS_DDCx */
+ sdvo->ddc_bus = 1 << num_bits;
+}
/**
* Choose the appropriate DDC bus for control bus switch command for this
@@ -1948,7 +1983,10 @@ intel_sdvo_select_ddc_bus(struct drm_i915_private *dev_priv,
else
mapping = &(dev_priv->sdvo_mappings[1]);
- sdvo->ddc_bus = 1 << ((mapping->ddc_pin & 0xf0) >> 4);
+ if (mapping->initialized)
+ sdvo->ddc_bus = 1 << ((mapping->ddc_pin & 0xf0) >> 4);
+ else
+ intel_sdvo_guess_ddc_bus(sdvo);
}
static bool