From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
commit a04e23d42a1ce5d5f421692bb1c7e9352832819d upstream
Update CDCLK_FREQ on BDW after changing the cdclk frequency. Not sure
if this is a late addition to the spec, or if I simply overlooked this
step when writing the original code.
This is what Bspec has to say about CDCLK_FREQ:
"Program this field to the CD clock frequency minus one. This is used to
generate a divided down clock for miscellaneous timers in display."
And the "Broadwell Sequences for Changing CD Clock Frequency" section
clarifies this further:
"For CD clock 337.5 MHz, program 337 decimal.
For CD clock 450 MHz, program 449 decimal.
For CD clock 540 MHz, program 539 decimal.
For CD clock 675 MHz, program 674 decimal."
Cc: <stable@xxxxxxxxxxxxxxx> # v4.4
Cc: Mika Kahola <mika.kahola@xxxxxxxxx>
Fixes: b432e5cfd5e9 ("drm/i915: BDW clock change support")
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/1461689194-6079-2-git-send-email-ville.syrjala@xxxxxxxxxxxxxxx
Reviewed-by: Mika Kahola <mika.kahola@xxxxxxxxx>
(cherry picked from commit 7f1052a8fa38df635ab0dc0e6025b64ab9834824)
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_reg.h | 2 ++
drivers/gpu/drm/i915/intel_display.c | 2 ++
2 files changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 7e461dca564c..9ed9f6dde86f 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7357,6 +7357,8 @@ enum skl_disp_power_wells {
#define TRANS_CLK_SEL_DISABLED (0x0<<29)
#define TRANS_CLK_SEL_PORT(x) (((x)+1)<<29)
+#define CDCLK_FREQ 0x46200
+
#define TRANSA_MSA_MISC 0x60410
#define TRANSB_MSA_MISC 0x61410
#define TRANSC_MSA_MISC 0x62410
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index afa81691163d..5ed9881785ef 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9669,6 +9669,8 @@ static void broadwell_set_cdclk(struct drm_device *dev, int cdclk)
sandybridge_pcode_write(dev_priv, HSW_PCODE_DE_WRITE_FREQ_REQ, data);
mutex_unlock(&dev_priv->rps.hw_lock);
+ I915_WRITE(CDCLK_FREQ, DIV_ROUND_CLOSEST(cdclk, 1000) - 1);
+
intel_update_cdclk(dev);
WARN(cdclk != dev_priv->cdclk_freq,
--
2.7.4
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