@@ -5006,6 +5006,9 @@ enum skl_disp_power_wells {
#define SWF1(i) (dev_priv->info.display_mmio_offset + 0x71410 + (i) * 4)
#define SWF3(i) (dev_priv->info.display_mmio_offset + 0x72414 + (i) * 4)
+/* VBIOS flag for display initialized status */
+#define GEN6_SWF18 (dev_priv->info.display_mmio_offset + 0x4F060)
+
/* Pipe B */
#define _PIPEBDSL (dev_priv->info.display_mmio_offset + 0x71000)
#define _PIPEBCONF (dev_priv->info.display_mmio_offset + 0x71008)
@@ -5761,6 +5761,14 @@ 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(GEN6_SWF18) & 0x00FFFF) == 0)
+ goto sanitize;
+
/* Is PLL enabled and locked ? */
if (!((lcpll1 & LCPLL_PLL_ENABLE) && (lcpll1 & LCPLL_PLL_LOCK)))
goto sanitize;
SWF18 is set if the display has been intialized by the pre-os. It also gives what configuration is enabled on which pipe. In skl_sanitize_cdclk, the DPLL sanity check can pass even if GOP/VBIOS is not loaded as BIOS enables DPLL for integrated audio codec related programming. So fisrt check if SWF18 is set and then follow through with other DPLL and CDCLK verification. If not set then for sure we need to sanitize the cdclock. v2: Update the commit message for clarity (Siva) Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com> --- drivers/gpu/drm/i915/i915_reg.h | 3 +++ drivers/gpu/drm/i915/intel_display.c | 8 ++++++++ 2 files changed, 11 insertions(+)