drm/radeon: fix speaker allocation setup

commit 49104038 upstream.

If the sad_count is 0, set the hw to stereo and change
the error message to a warn.  A lot of monitors don't
set the speaker allocation block.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/gpu/drm/radeon/dce3_1_afmt.c

@@ -49,8 +49,8 @@ static void dce3_2_afmt_write_speaker_allocation(struct drm_encoder *encoder)
 
 	sad_count = drm_edid_to_speaker_allocation(radeon_connector->edid, &sadb);
 	if (sad_count < 0) {
-		DRM_ERROR("Couldn't read Speaker Allocation Data Block: %d\n", sad_count);
-		return;
+		DRM_DEBUG("Couldn't read Speaker Allocation Data Block: %d\n", sad_count);
+		sad_count = 0;
 	}
 
 	/* program the speaker allocation */

drivers/gpu/drm/radeon/dce6_afmt.c

@@ -174,9 +174,9 @@ void dce6_afmt_write_speaker_allocation(struct drm_encoder *encoder)
 	}
 
 	sad_count = drm_edid_to_speaker_allocation(radeon_connector->edid, &sadb);
-	if (sad_count <= 0) {
-		DRM_ERROR("Couldn't read Speaker Allocation Data Block: %d\n", sad_count);
-		return;
+	if (sad_count < 0) {
+		DRM_DEBUG("Couldn't read Speaker Allocation Data Block: %d\n", sad_count);
+		sad_count = 0;
 	}
 
 	/* program the speaker allocation */

drivers/gpu/drm/radeon/evergreen_hdmi.c

@@ -118,9 +118,9 @@ static void dce4_afmt_write_speaker_allocation(struct drm_encoder *encoder)
 	}
 
 	sad_count = drm_edid_to_speaker_allocation(radeon_connector->edid, &sadb);
-	if (sad_count <= 0) {
-		DRM_ERROR("Couldn't read Speaker Allocation Data Block: %d\n", sad_count);
-		return;
+	if (sad_count < 0) {
+		DRM_DEBUG("Couldn't read Speaker Allocation Data Block: %d\n", sad_count);
+		sad_count = 0;
 	}
 
 	/* program the speaker allocation */