From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
BXT could change the CD2X divider synchronized with a single pipe.
So assuming the DE PLL frequency doesn't need to be changed, we could
change cdclk without shutting off the pipe (when only a single pipe is
enabled). In the meantime let's configure CDCLK_CTL for non-double
buffered CD2X update, although it shouldn't really matter as long as
the selected pipe is disabled when reprogramming the divider.
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_reg.h | 5 +++--
drivers/gpu/drm/i915/intel_display.c | 5 +++++
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 54ce0b105956..27a781260d33 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7566,14 +7566,15 @@ enum skl_disp_power_wells {
#define CDCLK_FREQ_540 (1<<26)
#define CDCLK_FREQ_337_308 (2<<26)
#define CDCLK_FREQ_675_617 (3<<26)
-#define CDCLK_FREQ_DECIMAL_MASK (0x7ff)
-
+#define BXT_CDCLK_CD2X_PIPE(pipe) ((pipe)<<20)
+#define BXT_CDCLK_CD2X_PIPE_NONE BXT_CDCLK_CD2X_PIPE(3)
#define BXT_CDCLK_CD2X_DIV_SEL_MASK (3<<22)
#define BXT_CDCLK_CD2X_DIV_SEL_1 (0<<22)
#define BXT_CDCLK_CD2X_DIV_SEL_1_5 (1<<22)
#define BXT_CDCLK_CD2X_DIV_SEL_2 (2<<22)
#define BXT_CDCLK_CD2X_DIV_SEL_4 (3<<22)
#define BXT_CDCLK_SSA_PRECHARGE_ENABLE (1<<16)
+#define CDCLK_FREQ_DECIMAL_MASK (0x7ff)
/* LCPLL_CTL */
#define LCPLL1_CTL _MMIO(0x46010)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 61133fdedc8d..39990bfe47f2 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5434,6 +5434,11 @@ static void broxton_set_cdclk(struct drm_i915_private *dev_priv, int cdclk)
DRM_ERROR("timeout waiting for DE PLL lock\n");
val = I915_READ(CDCLK_CTL);
+ /*
+ * FIXME if only the cd2x divider needs changing, it could be done
+ * without shutting off the pipe (if only one pipe is active).
+ */
+ val |= BXT_CDCLK_CD2X_PIPE_NONE;
val &= ~BXT_CDCLK_CD2X_DIV_SEL_MASK;
val |= divider;
/*
--
2.7.4
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