[PATCH 18/15] drm/i915: Preserve VGACNTR bits from the BIOS

[ville.syrjala@linux.intel.com]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

My Fujistsu-Siemens Lifebook S6010 doesn't like to resume from
S3 unless VGACNTR has been restore to the original value. The BIOS
value in this case was 0x0124008E. Setting the "VGA disable" bit
doesn't interfere with the S3 resume fortunately.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h      | 2 ++
 drivers/gpu/drm/i915/intel_display.c | 8 +++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 10e9f68..c1862c8 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1541,6 +1541,8 @@ struct drm_i915_private {
 	/* used to control DVO 2x clock enable on 830M */
 	uint8_t dvo_pipes;
 
+	uint32_t bios_vgacntr;
+
 	/* Old dri1 support infrastructure, beware the dragons ya fools entering
 	 * here! */
 	struct i915_dri1_state dri1;
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 4004605..12f7e8c 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -11946,7 +11946,11 @@ static void i915_disable_vga(struct drm_device *dev)
 	vga_put(dev->pdev, VGA_RSRC_LEGACY_IO);
 	udelay(300);
 
-	I915_WRITE(vga_reg, VGA_DISP_DISABLE);
+	/*
+	 * Fujitsu-Siemens Lifebook S6010 (830) has problems resuming
+	 * from S3 without preserving (some of?) the other bits.
+	 */
+	I915_WRITE(vga_reg, dev_priv->bios_vgacntr | VGA_DISP_DISABLE);
 	POSTING_READ(vga_reg);
 }
 
@@ -12033,6 +12037,8 @@ void intel_modeset_init(struct drm_device *dev)
 	intel_cpu_pll_init(dev);
 	intel_shared_dpll_init(dev);
 
+	/* save the BIOS value before clobbering it */
+	dev_priv->bios_vgacntr = I915_READ(i915_vgacntrl_reg(dev));
 	/* Just disable it once at startup */
 	i915_disable_vga(dev);
 	intel_setup_outputs(dev);
-- 
1.8.5.5

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