Read from DPCD receiver capability field for the following
features:
 - max TMDS clock rate
 - max bits per component
 - single or dual link support
 - high color depth support

Signed-off-by: Mika Kahola <mika.kahola at intel.com>
---
 drivers/gpu/drm/drm_dp_helper.c |  5 +++++
 include/drm/drm_dp_helper.h     | 14 ++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index c5bec6f..f5cf706 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -451,6 +451,11 @@ int drm_dp_bd(struct drm_dp_aux *aux, struct drm_dp_bd *bd)
                if (bd->type & DP_DS_PORT_TYPE_VGA) {
                        bd->dfp.vga.dot_clk = info[1] * 8 * 1000;
                        bd->dfp.vga.bpc = info[2] & DP_DS_VGA_MAX_BPC_MASK;
+               } else if (bd->type & DP_DS_PORT_TYPE_DVI) {
+                       bd->dfp.dvi.tmds_clk = info[1] * 2500;
+                       bd->dfp.dvi.bpc = info[2] & DP_DS_VGA_MAX_BPC_MASK;
+                       bd->dfp.dvi.dual_link = info[3] & DP_DS_DVI_DUAL_LINK;
+                       bd->dfp.dvi.hi_color_depth = info[3] & 
DP_DS_DVI_HI_COLOR_DEPTH;
                }
        }

diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index fe6cfdc..da82459 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -220,6 +220,9 @@
 # define DP_DS_VGA_10BPC                   1
 # define DP_DS_VGA_12BPC                   2
 # define DP_DS_VGA_16BPC                   3
+/* offset 3 for DVI dual link and high color depth */
+# define DP_DS_DVI_DUAL_LINK                (1<<1)
+# define DP_DS_DVI_HI_COLOR_DEPTH           (1<<2)

 /* link configuration */
 #define        DP_LINK_BW_SET                      0x100
@@ -810,6 +813,16 @@ struct drm_dp_vga {
 };

 /*
+ * DP to DVI
+ */
+struct drm_dp_dvi {
+       int tmds_clk;
+       uint8_t bpc;
+       bool dual_link;
+       bool hi_color_depth;
+};
+
+/*
  * Branch device
  */
 struct drm_dp_bd {
@@ -818,6 +831,7 @@ struct drm_dp_bd {
        bool hpd;
        union {
                struct drm_dp_vga vga;
+               struct drm_dp_dvi dvi;
        } dfp;
 };

-- 
1.9.1

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