drm/i915: properly handle interlaced bit for sdvo dtd conversion

We've simply ignored this, which isn't too great. With this, interlaced
1080i works on my HDMI screen connected through sdvo. For no apparent
reason anything else still doesn't work as it should.

While at it, give these magic numbers in the dtd proper names and
add a comment that they match with EDID detailed timings.

v2: Actually use the right bit for interlaced.
Tested-by: NPeter Ross <pross@xvid.org>
Reviewed-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Cc: stable@vger.kernel.org
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_sdvo.c

@@ -783,10 +783,12 @@ static void intel_sdvo_get_dtd_from_mode(struct intel_sdvo_dtd *dtd,
 		((v_sync_len & 0x30) >> 4);
 
 	dtd->part2.dtd_flags = 0x18;
+	if (mode->flags & DRM_MODE_FLAG_INTERLACE)
+		dtd->part2.dtd_flags |= DTD_FLAG_INTERLACE;
 	if (mode->flags & DRM_MODE_FLAG_PHSYNC)
-		dtd->part2.dtd_flags |= 0x2;
+		dtd->part2.dtd_flags |= DTD_FLAG_HSYNC_POSITIVE;
 	if (mode->flags & DRM_MODE_FLAG_PVSYNC)
-		dtd->part2.dtd_flags |= 0x4;
+		dtd->part2.dtd_flags |= DTD_FLAG_VSYNC_POSITIVE;
 
 	dtd->part2.sdvo_flags = 0;
 	dtd->part2.v_sync_off_high = v_sync_offset & 0xc0;
@@ -820,9 +822,11 @@ static void intel_sdvo_get_mode_from_dtd(struct drm_display_mode * mode,
 	mode->clock = dtd->part1.clock * 10;
 
 	mode->flags &= ~(DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
-	if (dtd->part2.dtd_flags & 0x2)
+	if (dtd->part2.dtd_flags & DTD_FLAG_INTERLACE)
+		mode->flags |= DRM_MODE_FLAG_INTERLACE;
+	if (dtd->part2.dtd_flags & DTD_FLAG_HSYNC_POSITIVE)
 		mode->flags |= DRM_MODE_FLAG_PHSYNC;
-	if (dtd->part2.dtd_flags & 0x4)
+	if (dtd->part2.dtd_flags & DTD_FLAG_VSYNC_POSITIVE)
 		mode->flags |= DRM_MODE_FLAG_PVSYNC;
 }
 

drivers/gpu/drm/i915/intel_sdvo_regs.h

@@ -61,6 +61,11 @@ struct intel_sdvo_caps {
 	u16 output_flags;
 } __attribute__((packed));
 
+/* Note: SDVO detailed timing flags match EDID misc flags. */
+#define DTD_FLAG_HSYNC_POSITIVE (1 << 1)
+#define DTD_FLAG_VSYNC_POSITIVE (1 << 2)
+#define DTD_FLAG_INTERLACE	(1 << 7)
+
 /** This matches the EDID DTD structure, more or less */
 struct intel_sdvo_dtd {
 	struct {