The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 7f1052a8fa38df635ab0dc0e6025b64ab9834824 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@xxxxxxxxxxxxxxx>
Date: Tue, 26 Apr 2016 19:46:32 +0300
Subject: [PATCH] drm/i915: Update CDCLK_FREQ register on BDW after changing
cdclk frequency
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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
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>
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 0a2fd3000f94..fd19f57f0736 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7518,6 +7518,8 @@ enum skl_disp_power_wells {
#define TRANS_CLK_SEL_DISABLED (0x0<<29)
#define TRANS_CLK_SEL_PORT(x) (((x)+1)<<29)
+#define CDCLK_FREQ _MMIO(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 2f36414702fe..084edf78227c 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9682,6 +9682,8 @@ 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,
--
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