drm/edid: detect SCDC support in HF-VSDB

This patch does following:
- Adds a new structure (drm_hdmi_info) in drm_display_info.
  This structure will be used to save and indicate if sink
  supports advanced HDMI 2.0 features
- Adds another structure drm_scdc within drm_hdmi_info, to
  reflect scdc support and capabilities in connected HDMI 2.0 sink.
- Checks the HF-VSDB block for presence of SCDC, and marks it
  in scdc structure
- If SCDC is present, checks if sink is capable of generating
  SCDC read request, and marks it in scdc structure.

V2: Addressed review comments
  Thierry:
  - Fix typos in commit message and make abbreviation consistent
    across the commit message.
  - Change structure object name from hdmi_info -> hdmi
  - Fix typos and abbreviations in description of structure drm_hdmi_info
    end the description with a full stop.
  - Create a structure drm_scdc, and keep all information related to SCDC
    register set (supported, read request supported) etc in it.

  Ville:
  - Change rr -> read_request
  - Call drm_detect_scrambling function drm_parse_hf_vsdb so that all
    of HF-VSDB parsing can be kept in same function, in incremental
    patches.

V3: Rebase.
V4: Rebase.
V5: Rebase.
V6: Addressed review comments from Ville
  - Add clock rate calculations for 1/10 and 1/40 ratios
  - Remove leftovers from old patchset
V7: Added R-B from Jose.
V8: Rebase.
V9: Rebase.
V10: Rebase.

Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1489404244-16608-5-git-send-email-shashank.sharma@intel.com

1 files changed, 32 insertions, 1 deletions

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index d6f16c02afb5..99144f879a4f 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -37,6 +37,7 @@
 #include <drm/drm_edid.h>
 #include <drm/drm_encoder.h>
 #include <drm/drm_displayid.h>
+#include <drm/drm_scdc_helper.h>
 
 #include "drm_crtc_internal.h"
 
@@ -3817,13 +3818,43 @@ EXPORT_SYMBOL(drm_default_rgb_quant_range);
 static void drm_parse_hdmi_forum_vsdb(struct drm_connector *connector,
 				 const u8 *hf_vsdb)
 {
-	struct drm_hdmi_info *hdmi = &connector->display_info.hdmi;
+	struct drm_display_info *display = &connector->display_info;
+	struct drm_hdmi_info *hdmi = &display->hdmi;
 
 	if (hf_vsdb[6] & 0x80) {
 		hdmi->scdc.supported = true;
 		if (hf_vsdb[6] & 0x40)
 			hdmi->scdc.read_request = true;
 	}
+
+	/*
+	 * All HDMI 2.0 monitors must support scrambling at rates > 340 MHz.
+	 * And as per the spec, three factors confirm this:
+	 * * Availability of a HF-VSDB block in EDID (check)
+	 * * Non zero Max_TMDS_Char_Rate filed in HF-VSDB (let's check)
+	 * * SCDC support available (let's check)
+	 * Lets check it out.
+	 */
+
+	if (hf_vsdb[5]) {
+		/* max clock is 5000 KHz times block value */
+		u32 max_tmds_clock = hf_vsdb[5] * 5000;
+		struct drm_scdc *scdc = &hdmi->scdc;
+
+		if (max_tmds_clock > 340000) {
+			display->max_tmds_clock = max_tmds_clock;
+			DRM_DEBUG_KMS("HF-VSDB: max TMDS clock %d kHz\n",
+				display->max_tmds_clock);
+		}
+
+		if (scdc->supported) {
+			scdc->scrambling.supported = true;
+
+			/* Few sinks support scrambling for cloks < 340M */
+			if ((hf_vsdb[6] & 0x8))
+				scdc->scrambling.low_rates = true;
+		}
+	}
 }
 
 static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,