[PATCH 1/1] drm/nv40: add LVDS table quirk for Dell Latitude D620

[Andy Whitcroft]

From: Ben Skeggs <bskeggs at redhat.com>

Should fix:
 https://bugzilla.redhat.com/show_bug.cgi?id=505132
 https://bugzilla.redhat.com/show_bug.cgi?id=543091
 https://bugzilla.redhat.com/show_bug.cgi?id=530425
 https://bugs.edge.launchpad.net/ubuntu/+source/xserver-xorg-video-nouveau/
 +bug/539730

Signed-off-by: Ben Skeggs <bskeggs at redhat.com>
(cherry picked from commit 8af36117e23bc36c34d0d25484f7b9de021b51bc git://cgit.freedesktop.org/nouveau/linux-2.6)

BugLink: http://bugs.launchpad.net/bugs/539730
Signed-off-by: Andy Whitcroft <apw at canonical.com>
---
 drivers/gpu/drm/nouveau/nouveau_bios.c |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_bios.c b/drivers/gpu/drm/nouveau/nouveau_bios.c
index 0e9cd1d..5480c14 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bios.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bios.c
@@ -3668,6 +3668,21 @@ int nouveau_bios_parse_lvds_table(struct drm_device *dev, int pxclk, bool *dl, b
 		break;
 	}
 
+	/* Dell Latitude D620 reports a too-high value for the dual-link
+	 * transition freq, causing us to program the panel incorrectly.
+	 *
+	 * It doesn't appear the VBIOS actually uses its transition freq
+	 * (90000kHz), instead it uses the "Number of LVDS channels" field
+	 * out of the panel ID structure (http://www.spwg.org/).
+	 *
+	 * For the moment, a quirk will do :)
+	 */
+	if ((dev->pdev->device == 0x01d7) &&
+	    (dev->pdev->subsystem_vendor == 0x1028) &&
+	    (dev->pdev->subsystem_device == 0x01c2)) {
+		bios->fp.duallink_transition_clk = 80000;
+	}
+
 	/* set dual_link flag for EDID case */
 	if (pxclk && (chip_version < 0x25 || chip_version > 0x28))
 		bios->fp.dual_link = (pxclk >= bios->fp.duallink_transition_clk);
-- 
1.7.0