From: Sonika Jindal <sonika.jin...@intel.com>

v2: Reading DP_EDP_REV, only when DISPLAY_CONTROL_CAPABLE field is set 
(Satheesh)

v3: Moving the utility function to drm_dp_helper (Daniel)

Signed-off-by: Sonika Jindal <sonika.jindal at intel.com>
---
 drivers/gpu/drm/drm_dp_helper.c |   15 +++++++++++++++
 include/drm/drm_dp_helper.h     |    2 ++
 2 files changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 08e33b8..a54a760 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -768,3 +768,18 @@ void drm_dp_aux_unregister(struct drm_dp_aux *aux)
        i2c_del_adapter(&aux->ddc);
 }
 EXPORT_SYMBOL(drm_dp_aux_unregister);
+
+bool drm_dp_is_edp_v1_4(struct drm_dp_aux *aux, const u8 
dpcd[DP_RECEIVER_CAP_SIZE])
+{
+       uint8_t reg;
+
+       if (dpcd[DP_EDP_CONFIGURATION_CAP] &
+                DP_DPCD_DISPLAY_CONTROL_CAPABLE) {
+
+               if (drm_dp_dpcd_read(aux, DP_EDP_REV, &reg, 1))
+                       if (reg == 0x03)
+                               return true;
+       }
+       return false;
+}
+EXPORT_SYMBOL(drm_dp_is_edp_v1_4);
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 8edeed0..b017e1e 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -102,6 +102,8 @@

 #define DP_EDP_CONFIGURATION_CAP            0x00d   /* XXX 1.2? */
 #define DP_TRAINING_AUX_RD_INTERVAL         0x00e   /* XXX 1.2? */
+#define DP_DPCD_DISPLAY_CONTROL_CAPABLE     (1 << 3)
+#define DP_EDP_REV                          0x700

 /* Multiple stream transport */
 #define DP_FAUX_CAP                        0x020   /* 1.2 */
-- 
1.7.10.4

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