[RFC 06/13] drm/dp: Read eDP version from DPCD

[Thierry Reding <thierry.reding@gmail.com>]

From: Thierry Reding <treding@nvidia.com>

If the sink support eDP, read the eDP revision from it's DPCD.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 drivers/gpu/drm/drm_dp_helper.c | 30 +++++++++++++++++++++++++++++-
 include/drm/drm_dp_helper.h     |  1 +
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 1fe181525604..c711b690508b 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -295,7 +295,7 @@ EXPORT_SYMBOL(drm_dp_dpcd_read_link_status);
  */
 int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link)
 {
-	u8 values[7];
+	u8 values[16], value;
 	int err;
 
 	memset(link, 0, sizeof(*link));
@@ -323,6 +323,34 @@ int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link)
 	if (values[6] & DP_SET_ANSI_8B10B)
 		link->capabilities |= DP_LINK_CAP_ANSI_8B10B;
 
+	if (values[13] & DP_ALTERNATE_SCRAMBLER_RESET_CAP) {
+		err = drm_dp_dpcd_readb(aux, DP_EDP_DPCD_REV, &value);
+		if (err < 0)
+			return err;
+
+		switch (value) {
+		case DP_EDP_11:
+			link->edp = 0x11;
+			break;
+
+		case DP_EDP_12:
+			link->edp = 0x12;
+			break;
+
+		case DP_EDP_13:
+			link->edp = 0x13;
+			break;
+
+		case DP_EDP_14:
+			link->edp = 0x14;
+			break;
+
+		default:
+			DRM_ERROR("unsupported eDP version: %02x\n", value);
+			break;
+		}
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL(drm_dp_link_probe);
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 9e70ea8b907d..f9e7f484a225 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -749,6 +749,7 @@ int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
 
 struct drm_dp_link {
 	unsigned char revision;
+	unsigned char edp;
 	unsigned int rate;
 	unsigned int num_lanes;
 	unsigned long capabilities;
-- 
2.4.5

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