From: Ville Syrjälä <ville.syrjala@linux.intel.com>
Date: Wed, 7 Oct 2015 19:08:24 +0000 (+0300)
Subject: drm/i915: Restore lost DPLL register write on gen2-4
X-Git-Tag: v4.2.6~70
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3b41bea2e6ee89b191e99fa7f9e8a576a93edd45;p=thirdparty%2Fkernel%2Fstable.git

drm/i915: Restore lost DPLL register write on gen2-4

commit 8e7a65aa70bcc1235a44e40ae0da5056525fe081 upstream.

We accidentally lost the initial DPLL register write in
1c4e02746147 drm/i915: Fix DVO 2x clock enable on 830M

The "three times for luck" hack probably saved us from a total
disaster. But anyway, bring the initial write back so that the
code actually makes some sense.

Reported-and-tested-by: Nick Bowler <nbowler@draconx.ca>
References: http://mid.gmane.org/CAN_QmVyMaArxYgEcVVsGvsMo7-6ohZr8HmF5VhkkL4i9KOmrhw@mail.gmail.com
Cc: Nick Bowler <nbowler@draconx.ca>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 107c6c0519fd8..fc4fd1b5b2c6e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1729,6 +1729,8 @@ static void i9xx_enable_pll(struct intel_crtc *crtc)
 			   I915_READ(DPLL(!crtc->pipe)) | DPLL_DVO_2X_MODE);
 	}
 
+	I915_WRITE(reg, dpll);
+
 	/* Wait for the clocks to stabilize. */
 	POSTING_READ(reg);
 	udelay(150);