patches.baytrail/0124-drm-i915-set-proper-DPIO-post-divider-for-VGA-on-VLV.patch

From 412c0089d9c529c571dc103885b206841d856db9 Mon Sep 17 00:00:00 2001
From: Jesse Barnes <jbarnes@virtuousgeek.org>
Date: Thu, 2 May 2013 10:48:09 -0700
Subject: drm/i915: set proper DPIO post divider for VGA on VLV v4

Supposedly we should use the DAC divider for <300MHz pixel clocks, but as
that doesn't actually work as well as the high freq divider here in
practice, just use the high freq divider all the time.

v2: remove unconditional write (Jesse)
    check for pixel rate properly (Jesse)
v3: give up, the DAC divider apparently doesn't work, and low res modes
    work ok (Jesse)
    remove debug msg (Jesse)

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit 7df5080bc7f3e3fba9cddac71133ed52864c40be)
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 745bcca57db6..b13dc43725da 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4474,10 +4474,13 @@ static void vlv_update_pll(struct intel_crtc *crtc)
 	mdiv |= ((bestp1 << DPIO_P1_SHIFT) | (bestp2 << DPIO_P2_SHIFT));
 	mdiv |= ((bestn << DPIO_N_SHIFT));
 	mdiv |= (1 << DPIO_K_SHIFT);
-	if (intel_pipe_has_type(&crtc->base, INTEL_OUTPUT_HDMI) ||
-	    intel_pipe_has_type(&crtc->base, INTEL_OUTPUT_EDP) ||
-	    intel_pipe_has_type(&crtc->base, INTEL_OUTPUT_DISPLAYPORT))
-		mdiv |= (DPIO_POST_DIV_HDMIDP << DPIO_POST_DIV_SHIFT);
+
+	/*
+	 * Post divider depends on pixel clock rate, DAC vs digital (and LVDS,
+	 * but we don't support that).
+	 * Note: don't use the DAC post divider as it seems unstable.
+	 */
+	mdiv |= (DPIO_POST_DIV_HDMIDP << DPIO_POST_DIV_SHIFT);
 	intel_dpio_write(dev_priv, DPIO_DIV(pipe), mdiv);
 
 	mdiv |= DPIO_ENABLE_CALIBRATION;
-- 
1.8.5.rc3