[PATCH 6.4 221/234] Revert "drm/edid: Fix csync detailed mode parsing"

[Greg Kroah-Hartman]

From: Jani Nikula <jani.nikula at intel.com>

commit 50b6f2c8297793f7f3315623db78dcff85158e96 upstream.

This reverts commit ca62297b2085b5b3168bd891ca24862242c635a1.

Commit ca62297b2085 ("drm/edid: Fix csync detailed mode parsing") fixed
EDID detailed mode sync parsing. Unfortunately, there are quite a few
displays out there that have bogus (zero) sync field that are broken by
the change. Zero means analog composite sync, which is not right for
digital displays, and the modes get rejected. Regardless, it used to
work, and it needs to continue to work. Revert the change.

Rejecting modes with analog composite sync was the part that fixed the
gitlab issue 8146 [1]. We'll need to get back to the drawing board with
that.

[1] https://gitlab.freedesktop.org/drm/intel/-/issues/8146

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8789
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8930
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9044
Fixes: ca62297b2085 ("drm/edid: Fix csync detailed mode parsing")
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: dri-devel at lists.freedesktop.org
Cc: <stable at vger.kernel.org> # v6.4+
Signed-off-by: Jani Nikula <jani.nikula at intel.com>
Acked-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230815101907.2900768-1-jani.nikula@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 drivers/gpu/drm/drm_edid.c |   29 ++++++++---------------------
 include/drm/drm_edid.h     |   12 +++---------
 2 files changed, 11 insertions(+), 30 deletions(-)

--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3424,6 +3424,10 @@ static struct drm_display_mode *drm_mode
 			    connector->base.id, connector->name);
 		return NULL;
 	}
+	if (!(pt->misc & DRM_EDID_PT_SEPARATE_SYNC)) {
+		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Composite sync not supported\n",
+			    connector->base.id, connector->name);
+	}
 
 	/* it is incorrect if hsync/vsync width is zero */
 	if (!hsync_pulse_width || !vsync_pulse_width) {
@@ -3470,27 +3474,10 @@ static struct drm_display_mode *drm_mode
 	if (info->quirks & EDID_QUIRK_DETAILED_SYNC_PP) {
 		mode->flags |= DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC;
 	} else {
-		switch (pt->misc & DRM_EDID_PT_SYNC_MASK) {
-		case DRM_EDID_PT_ANALOG_CSYNC:
-		case DRM_EDID_PT_BIPOLAR_ANALOG_CSYNC:
-			drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Analog composite sync!\n",
-				    connector->base.id, connector->name);
-			mode->flags |= DRM_MODE_FLAG_CSYNC | DRM_MODE_FLAG_NCSYNC;
-			break;
-		case DRM_EDID_PT_DIGITAL_CSYNC:
-			drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Digital composite sync!\n",
-				    connector->base.id, connector->name);
-			mode->flags |= DRM_MODE_FLAG_CSYNC;
-			mode->flags |= (pt->misc & DRM_EDID_PT_HSYNC_POSITIVE) ?
-				DRM_MODE_FLAG_PCSYNC : DRM_MODE_FLAG_NCSYNC;
-			break;
-		case DRM_EDID_PT_DIGITAL_SEPARATE_SYNC:
-			mode->flags |= (pt->misc & DRM_EDID_PT_HSYNC_POSITIVE) ?
-				DRM_MODE_FLAG_PHSYNC : DRM_MODE_FLAG_NHSYNC;
-			mode->flags |= (pt->misc & DRM_EDID_PT_VSYNC_POSITIVE) ?
-				DRM_MODE_FLAG_PVSYNC : DRM_MODE_FLAG_NVSYNC;
-			break;
-		}
+		mode->flags |= (pt->misc & DRM_EDID_PT_HSYNC_POSITIVE) ?
+			DRM_MODE_FLAG_PHSYNC : DRM_MODE_FLAG_NHSYNC;
+		mode->flags |= (pt->misc & DRM_EDID_PT_VSYNC_POSITIVE) ?
+			DRM_MODE_FLAG_PVSYNC : DRM_MODE_FLAG_NVSYNC;
 	}
 
 set_size:
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -61,15 +61,9 @@ struct std_timing {
 	u8 vfreq_aspect;
 } __attribute__((packed));
 
-#define DRM_EDID_PT_SYNC_MASK              (3 << 3)
-# define DRM_EDID_PT_ANALOG_CSYNC          (0 << 3)
-# define DRM_EDID_PT_BIPOLAR_ANALOG_CSYNC  (1 << 3)
-# define DRM_EDID_PT_DIGITAL_CSYNC         (2 << 3)
-#  define DRM_EDID_PT_CSYNC_ON_RGB         (1 << 1) /* analog csync only */
-#  define DRM_EDID_PT_CSYNC_SERRATE        (1 << 2)
-# define DRM_EDID_PT_DIGITAL_SEPARATE_SYNC (3 << 3)
-#  define DRM_EDID_PT_HSYNC_POSITIVE       (1 << 1) /* also digital csync */
-#  define DRM_EDID_PT_VSYNC_POSITIVE       (1 << 2)
+#define DRM_EDID_PT_HSYNC_POSITIVE (1 << 1)
+#define DRM_EDID_PT_VSYNC_POSITIVE (1 << 2)
+#define DRM_EDID_PT_SEPARATE_SYNC  (3 << 3)
 #define DRM_EDID_PT_STEREO         (1 << 5)
 #define DRM_EDID_PT_INTERLACED     (1 << 7)