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-rw-r--r--drivers/gpu/drm/i915/i915_reg.h1
-rw-r--r--drivers/gpu/drm/i915/intel_display.c8
2 files changed, 9 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 9ee9481..e8f1d42 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -5005,6 +5005,7 @@ enum skl_disp_power_wells {
#define SWF0(i) (dev_priv->info.display_mmio_offset + 0x70410 + (i) * 4)
#define SWF1(i) (dev_priv->info.display_mmio_offset + 0x71410 + (i) * 4)
#define SWF3(i) (dev_priv->info.display_mmio_offset + 0x72414 + (i) * 4)
+#define SWF_ILK(i) (0x4F000 + (i) * 4)
/* Pipe B */
#define _PIPEBDSL (dev_priv->info.display_mmio_offset + 0x71000)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 2e51642..ccf06faa 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5734,6 +5734,14 @@ int skl_sanitize_cdclk(struct drm_i915_private *dev_priv)
uint32_t cdctl = I915_READ(CDCLK_CTL);
int freq = dev_priv->skl_boot_cdclk;
+ /*
+ * check if the pre-os intialized the display
+ * There is SWF18 scratchpad register defined which is set by the
+ * pre-os which can be used by the OS drivers to check the status
+ */
+ if ((I915_READ(SWF_ILK(0x18)) & 0x00FFFFFF) == 0)
+ goto sanitize;
+
/* Is PLL enabled and locked ? */
if (!((lcpll1 & LCPLL_PLL_ENABLE) && (lcpll1 & LCPLL_PLL_LOCK)))
goto sanitize;
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