diff mbox series

[14/37] drm/i915/dg1: Initialize RAWCLK properly

Message ID 20200521003803.18936-15-lucas.demarchi@intel.com (mailing list archive)
State New, archived
Headers show
Series Introduce DG1 | expand

Commit Message

Lucas De Marchi May 21, 2020, 12:37 a.m. UTC 
From: Matt Roper <matthew.d.roper@intel.com>

DG1 always uses a 38.4 MHz rawclk rather and we don't need to read
fuse straps like on CNP+. frequencies on CNP+.  Note that register bits
associated with this frequency confusingly use 37 for the divider field
rather than 38 as you might expect.

For simplicity, let's just assume that this 38.4 MHz frequency will hold
true for other future platforms with "fake" PCH south displays and that
the CNP-style behavior will remain for other platforms with a real PCH.

Bspec: 49950
Bspec: 49309
Cc: Aditya Swarup <aditya.swarup@intel.com>
Cc: Clinton Taylor <Clinton.A.Taylor@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
---
 drivers/gpu/drm/i915/display/intel_cdclk.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
index 9419a4724357..567c36fc9fd7 100644
--- a/drivers/gpu/drm/i915/display/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
@@ -2659,6 +2659,19 @@  void intel_update_cdclk(struct drm_i915_private *dev_priv)
 		               DIV_ROUND_UP(dev_priv->cdclk.hw.cdclk, 1000));
 }
 
+static int dg1_rawclk(struct drm_i915_private *i915)
+{
+	/*
+	 * DG1 always uses a 38.4 MHz rawclk.  The bspec tells us
+	 * "Program Numerator=2, Denominator=4, Divider=37 decimal."
+	 */
+	intel_de_write(i915, PCH_RAWCLK_FREQ,
+		       CNP_RAWCLK_DEN(4) | CNP_RAWCLK_DIV(37) |
+		       ICP_RAWCLK_NUM(2));
+
+	return 38400;
+}
+
 static int cnp_rawclk(struct drm_i915_private *dev_priv)
 {
 	u32 rawclk;
@@ -2767,6 +2780,8 @@  u32 intel_read_rawclk(struct drm_i915_private *dev_priv)
 {
 	u32 freq;
 
+	if (INTEL_PCH_TYPE(dev_priv) >= PCH_DG1)
+		freq = dg1_rawclk(dev_priv);
 	if (INTEL_PCH_TYPE(dev_priv) >= PCH_CNP)
 		freq = cnp_rawclk(dev_priv);
 	else if (HAS_PCH_SPLIT(dev_priv))