[PATCH] drm/radeon/kms: fix legacy LVDS mode computation

[Jerome Glisse]

From: John Doe <glisse at ned.localdomain>

Compute downscaled mode timing like DDX does on legacy hw.
With this patch it's now possible to use non native laptop
panel resolution. Tested on M7 (7500) laptop.

Cc: <stable at kernel.org>
Signed-off-by: Jerome Glisse <jglisse at redhat.com>
---
 drivers/gpu/drm/radeon/radeon_legacy_encoders.c |   23 ++++++++++++++++++++++-
 1 files changed, 22 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_legacy_encoders.c b/drivers/gpu/drm/radeon/radeon_legacy_encoders.c
index 2441cca..0d78f5b 100644
--- a/drivers/gpu/drm/radeon/radeon_legacy_encoders.c
+++ b/drivers/gpu/drm/radeon/radeon_legacy_encoders.c
@@ -219,6 +219,8 @@ static bool radeon_legacy_mode_fixup(struct drm_encoder *encoder,
 	struct radeon_encoder *radeon_encoder = to_radeon_encoder(encoder);
 	struct drm_device *dev = encoder->dev;
 	struct radeon_device *rdev = dev->dev_private;
+	unsigned hsync_width, vsync_width;
+	unsigned hover, vover, hblank, vblank;
 
 	/* adjust pm to upcoming mode change */
 	radeon_pm_compute_clocks(rdev);
@@ -237,8 +239,27 @@ static bool radeon_legacy_mode_fixup(struct drm_encoder *encoder,
 		adjusted_mode->crtc_hdisplay = mode->hdisplay;
 		adjusted_mode->crtc_vdisplay = mode->vdisplay;
 		adjusted_mode->base.id = mode_id;
+		hblank = native_mode->htotal - native_mode->hdisplay;
+		vblank = native_mode->vtotal - native_mode->vdisplay;
+		hover = native_mode->hsync_start - native_mode->hdisplay;
+		vover = native_mode->vsync_start - native_mode->vdisplay;
+		hsync_width = native_mode->hsync_end - native_mode->hsync_start;
+		vsync_width = native_mode->vsync_end - native_mode->vsync_start;
+		adjusted_mode->crtc_hsync_start = mode->hdisplay + hover;
+		adjusted_mode->crtc_hsync_end = adjusted_mode->crtc_hsync_start + hsync_width;
+		adjusted_mode->crtc_htotal = mode->hdisplay + hblank;
+		adjusted_mode->crtc_vsync_start = mode->vdisplay + vover;
+		adjusted_mode->crtc_vsync_end = adjusted_mode->crtc_vsync_start + vsync_width;
+		adjusted_mode->crtc_vtotal = mode->vdisplay + vblank;
+		adjusted_mode->crtc_hblank_start = mode->hdisplay;
+		adjusted_mode->crtc_vblank_start = mode->vdisplay;
+		adjusted_mode->hsync_start = adjusted_mode->crtc_hsync_start;
+		adjusted_mode->hsync_end = adjusted_mode->crtc_hsync_end;
+		adjusted_mode->htotal = adjusted_mode->crtc_htotal;
+		adjusted_mode->vsync_start = adjusted_mode->crtc_vsync_start;
+		adjusted_mode->vsync_end = adjusted_mode->crtc_vsync_end;
+		adjusted_mode->vtotal = adjusted_mode->crtc_vtotal;
 	}
-
 	return true;
 }
 
-- 
1.7.0.1