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[02/12] drm/i915: Fix 852GM/GMV cdclk

Message ID 1429170058-15158-3-git-send-email-mika.kahola@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Mika Kahola April 16, 2015, 7:40 a.m. UTC 
From: Ville Syrjälä <ville.syrjala@linux.intel.com>

It seems 852GM/GMV uses a different HPLLCC encoding than the other
85x platforms. For 852GM/GMV cdclk is always 133MHz. Try to detect that
using the PCI revision (sinc the device ID seems useless for that). I'm
not at all sure this is a good idea, but according to the specs it
should work.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

v2: Rebased to the latest

Signed-off-by: Mika Kahola <mika.kahola@intel.com>

Author:    Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 8 ++++++++
 1 file changed, 8 insertions(+)
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Patch

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 71123c7..7afde69 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6305,6 +6305,14 @@  static int i85x_get_display_clock_speed(struct drm_device *dev)
 {
 	u16 hpllcc = 0;
 
+	/*
+	 * 852GM/852GMV only supports 133 MHz and the HPLLCC
+	 * encoding is different :(
+	 * FIXME is this the right way to detect 852GM/852GMV?
+	 */
+	if (dev->pdev->revision == 0x1)
+		return 133333;
+
 	pci_bus_read_config_word(dev->pdev->bus,
 				 PCI_DEVFN(0, 3), HPLLCC, &hpllcc);