On 11/02/2015 06:40 PM, Jani Nikula wrote:
On Mon, 02 Nov 2015, Shobhit Kumar <shobhit.kumar@xxxxxxxxx> wrote:
SWF18 is set if the display has been intialized by the pre-os. It
also gives what configuration is enabled on which pipe. The DPLL and
CDCLK verification checks can fail as the pre-os does initialize the
DPLL for Audio codec initialization. So fisrt check if SWF18 is set and
then follow through with other DPLL and CDCLK verification.
Can we universally trust all bios/gop/bootloader/whatnot to have
initialized this? What if it's not set?
As per my discussion with gop team, this has been enabled in main stream
for quite sometime including VLV, CHT, BDW, SKL+ and is common for
GOP/VBIOS across chrome/windows/android. So yes I think we can
universally trust as of now.
Regards
Shobhit
BR,
Jani.
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Signed-off-by: Shobhit Kumar <shobhit.kumar@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_reg.h | 3 +++
drivers/gpu/drm/i915/intel_display.c | 8 ++++++++
2 files changed, 11 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 9ee9481..bd476ff 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -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)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 103cacb..0ecb35c 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -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;
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