drm/i915: Skip modifying PCH DREF if not changing clock sources
Modifying the clock sources (via the DREF control on the PCH) is a slow multi-stage process as we need to let the clocks stabilise between each stage. If we are not actually changing the clock sources, then we can return early. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Jani Nikula <jani.nikula@intel.com> [danvet: Appease checkpatch by deleting a space after a ~] Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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@ -4701,7 +4701,7 @@ static void ironlake_init_pch_refclk(struct drm_device *dev)
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struct drm_i915_private *dev_priv = dev->dev_private;
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struct drm_mode_config *mode_config = &dev->mode_config;
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struct intel_encoder *encoder;
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u32 temp;
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u32 val, final;
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bool has_lvds = false;
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bool has_cpu_edp = false;
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bool has_pch_edp = false;
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@ -4744,70 +4744,109 @@ static void ironlake_init_pch_refclk(struct drm_device *dev)
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* PCH B stepping, previous chipset stepping should be
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* ignoring this setting.
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*/
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temp = I915_READ(PCH_DREF_CONTROL);
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/* Always enable nonspread source */
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temp &= ~DREF_NONSPREAD_SOURCE_MASK;
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val = I915_READ(PCH_DREF_CONTROL);
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/* As we must carefully and slowly disable/enable each source in turn,
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* compute the final state we want first and check if we need to
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* make any changes at all.
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*/
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final = val;
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final &= ~DREF_NONSPREAD_SOURCE_MASK;
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if (has_ck505)
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temp |= DREF_NONSPREAD_CK505_ENABLE;
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final |= DREF_NONSPREAD_CK505_ENABLE;
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else
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temp |= DREF_NONSPREAD_SOURCE_ENABLE;
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final |= DREF_NONSPREAD_SOURCE_ENABLE;
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final &= ~DREF_SSC_SOURCE_MASK;
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final &= ~DREF_CPU_SOURCE_OUTPUT_MASK;
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final &= ~DREF_SSC1_ENABLE;
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if (has_panel) {
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temp &= ~DREF_SSC_SOURCE_MASK;
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temp |= DREF_SSC_SOURCE_ENABLE;
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final |= DREF_SSC_SOURCE_ENABLE;
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if (intel_panel_use_ssc(dev_priv) && can_ssc)
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final |= DREF_SSC1_ENABLE;
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if (has_cpu_edp) {
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if (intel_panel_use_ssc(dev_priv) && can_ssc)
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final |= DREF_CPU_SOURCE_OUTPUT_DOWNSPREAD;
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else
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final |= DREF_CPU_SOURCE_OUTPUT_NONSPREAD;
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} else
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final |= DREF_CPU_SOURCE_OUTPUT_DISABLE;
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} else {
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final |= DREF_SSC_SOURCE_DISABLE;
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final |= DREF_CPU_SOURCE_OUTPUT_DISABLE;
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}
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if (final == val)
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return;
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/* Always enable nonspread source */
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val &= ~DREF_NONSPREAD_SOURCE_MASK;
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if (has_ck505)
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val |= DREF_NONSPREAD_CK505_ENABLE;
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else
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val |= DREF_NONSPREAD_SOURCE_ENABLE;
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if (has_panel) {
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val &= ~DREF_SSC_SOURCE_MASK;
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val |= DREF_SSC_SOURCE_ENABLE;
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/* SSC must be turned on before enabling the CPU output */
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if (intel_panel_use_ssc(dev_priv) && can_ssc) {
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DRM_DEBUG_KMS("Using SSC on panel\n");
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temp |= DREF_SSC1_ENABLE;
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val |= DREF_SSC1_ENABLE;
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} else
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temp &= ~DREF_SSC1_ENABLE;
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val &= ~DREF_SSC1_ENABLE;
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/* Get SSC going before enabling the outputs */
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I915_WRITE(PCH_DREF_CONTROL, temp);
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I915_WRITE(PCH_DREF_CONTROL, val);
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POSTING_READ(PCH_DREF_CONTROL);
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udelay(200);
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temp &= ~DREF_CPU_SOURCE_OUTPUT_MASK;
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val &= ~DREF_CPU_SOURCE_OUTPUT_MASK;
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/* Enable CPU source on CPU attached eDP */
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if (has_cpu_edp) {
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if (intel_panel_use_ssc(dev_priv) && can_ssc) {
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DRM_DEBUG_KMS("Using SSC on eDP\n");
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temp |= DREF_CPU_SOURCE_OUTPUT_DOWNSPREAD;
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val |= DREF_CPU_SOURCE_OUTPUT_DOWNSPREAD;
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}
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else
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temp |= DREF_CPU_SOURCE_OUTPUT_NONSPREAD;
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val |= DREF_CPU_SOURCE_OUTPUT_NONSPREAD;
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} else
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temp |= DREF_CPU_SOURCE_OUTPUT_DISABLE;
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val |= DREF_CPU_SOURCE_OUTPUT_DISABLE;
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I915_WRITE(PCH_DREF_CONTROL, temp);
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I915_WRITE(PCH_DREF_CONTROL, val);
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POSTING_READ(PCH_DREF_CONTROL);
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udelay(200);
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} else {
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DRM_DEBUG_KMS("Disabling SSC entirely\n");
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temp &= ~DREF_CPU_SOURCE_OUTPUT_MASK;
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val &= ~DREF_CPU_SOURCE_OUTPUT_MASK;
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/* Turn off CPU output */
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temp |= DREF_CPU_SOURCE_OUTPUT_DISABLE;
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val |= DREF_CPU_SOURCE_OUTPUT_DISABLE;
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I915_WRITE(PCH_DREF_CONTROL, temp);
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I915_WRITE(PCH_DREF_CONTROL, val);
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POSTING_READ(PCH_DREF_CONTROL);
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udelay(200);
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/* Turn off the SSC source */
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temp &= ~DREF_SSC_SOURCE_MASK;
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temp |= DREF_SSC_SOURCE_DISABLE;
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val &= ~DREF_SSC_SOURCE_MASK;
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val |= DREF_SSC_SOURCE_DISABLE;
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/* Turn off SSC1 */
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temp &= ~ DREF_SSC1_ENABLE;
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val &= ~DREF_SSC1_ENABLE;
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I915_WRITE(PCH_DREF_CONTROL, temp);
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I915_WRITE(PCH_DREF_CONTROL, val);
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POSTING_READ(PCH_DREF_CONTROL);
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udelay(200);
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}
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BUG_ON(val != final);
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}
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/* Sequence to enable CLKOUT_DP for FDI usage and configure PCH FDI I/O. */
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