drm/amd/display: Restore ALLM support in HDMI vsif

[Why]
Support for triggering ALLM in modern TVs is missing.

When HDMI vsif was added in 2019:
commit 3c2381b ("drm/amd/display: add support for VSIP info packet")
it was improperly handeled as HDMI actually has two separate vsifs. The
implementation was based on H14b-vsif and ALLM bit was messing it up
because H14b-vsif doesn't support ALLM. It was later removed in:
commit 75f77aa ("drm/amd/display: Send H14b-VSIF specified in HDMI")

ALLM is supported by hf-vsif (HDMI Forum) instead.

[How]
Add proper logic to construct either h14b-vsif or hf-vsif based on
required capabilities. Currently, only ALLM from hf-vsif is supported.

Turns out, hf-vsif is almost identical to h14b-vsif, BUT has additional
two bytes of data after OUI. First byte is static and seems like
a version supported by leftover define. Second byte consists of 3D and
ALLM bits.

Implement logic to offset 3D data if building hf-vsif.

Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@gmail.com>

Author: Lawstorant

drivers/gpu/drm/amd/display/modules/info_packet/info_packet.c

@@ -49,7 +49,10 @@ enum vsc_packet_revision {
 };
 
 #define HDMI_INFOFRAME_TYPE_VENDOR 0x81
-#define HF_VSIF_VERSION 1
+#define HDMI_INFOFRAME_LENGTH_MASK 0x1F
+#define HF_VSIF_VERSION  1
+#define HF_VSIF_3D_BIT   0
+#define HF_VSIF_ALLM_BIT 1
 
 // VTEM Byte Offset
 #define VTEM_PB0		0
@@ -496,73 +499,105 @@ void mod_build_vsc_infopacket(const struct dc_stream_state *stream,
 	}
 }
 
+static bool is_hdmi_vic_mode(const struct dc_stream_state *stream)
+{
+	if (stream->timing.hdmi_vic == 0)
+		return false;
+
+	if (stream->timing.h_total < 3840 ||
+	    stream->timing.v_total < 2160)
+		return false;
+
+	/* 3D/ALLM forces HDMI VIC -> CTA VIC translation */
+	if (stream->view_format != VIEW_3D_FORMAT_NONE)
+		return false;
+
+	if (stream->link->local_sink->edid_caps.allm)
+		return false;
+
+	return true;
+}
+
 /**
  *  mod_build_hf_vsif_infopacket - Prepare HDMI Vendor Specific info frame.
  *                                 Follows HDMI Spec to build up Vendor Specific info frame
+ *                                 Conforms to h14b-vsif or hf-vsif based on the capabilities
  *
  *  @stream:      contains data we may need to construct VSIF (i.e. timing_3d_format, etc.)
  *  @info_packet: output structure where to store VSIF
  */
 void mod_build_hf_vsif_infopacket(const struct dc_stream_state *stream,
 		struct dc_info_packet *info_packet)
 {
-		unsigned int length = 5;
 		bool hdmi_vic_mode = false;
+		bool allm = false;
+		bool stereo = false;
 		uint8_t checksum = 0;
-		uint32_t i = 0;
+		uint8_t offset = 0;
+		uint8_t i = 0;
+		uint8_t length = 5;
+		uint32_t oui = HDMI_IEEE_OUI;
 		enum dc_timing_3d_format format;
 
 		info_packet->valid = false;
+
 		format = stream->timing.timing_3d_format;
 		if (stream->view_format == VIEW_3D_FORMAT_NONE)
 			format = TIMING_3D_FORMAT_NONE;
+		stereo = format != TIMING_3D_FORMAT_NONE;
+		hdmi_vic_mode = is_hdmi_vic_mode(stream);
 
-		if (stream->timing.hdmi_vic != 0
-				&& stream->timing.h_total >= 3840
-				&& stream->timing.v_total >= 2160
-				&& format == TIMING_3D_FORMAT_NONE)
-			hdmi_vic_mode = true;
-
-		if ((format == TIMING_3D_FORMAT_NONE) && !hdmi_vic_mode)
+		if (!stereo && !hdmi_vic_mode && !allm)
 			return;
 
-		info_packet->sb[1] = 0x03;
-		info_packet->sb[2] = 0x0C;
-		info_packet->sb[3] = 0x00;
+		if (allm)
+			oui = HDMI_FORUM_IEEE_OUI;
 
-		if (format != TIMING_3D_FORMAT_NONE)
-			info_packet->sb[4] = (2 << 5);
+		info_packet->sb[1] = oui & 0xFF;
+		info_packet->sb[2] = (oui >> 8) & 0xFF;
+		info_packet->sb[3] = (oui >> 16) & 0xFF;
 
-		else if (hdmi_vic_mode)
-			info_packet->sb[4] = (1 << 5);
+		if (oui == HDMI_FORUM_IEEE_OUI) {
+			offset = 2;
+			length += 2;
+			info_packet->sb[4] = HF_VSIF_VERSION;
+			info_packet->sb[5] = stereo << HF_VSIF_3D_BIT;
+			info_packet->sb[5] |= allm << HF_VSIF_ALLM_BIT;
+		}
 
-		switch (format) {
-		case TIMING_3D_FORMAT_HW_FRAME_PACKING:
-		case TIMING_3D_FORMAT_SW_FRAME_PACKING:
-			info_packet->sb[5] = (0x0 << 4);
-			break;
+		if (stereo) {
+			info_packet->sb[4 + offset] = (2 << 5);
 
-		case TIMING_3D_FORMAT_SIDE_BY_SIDE:
-		case TIMING_3D_FORMAT_SBS_SW_PACKED:
-			info_packet->sb[5] = (0x8 << 4);
-			length = 6;
-			break;
+			switch (format) {
+			case TIMING_3D_FORMAT_HW_FRAME_PACKING:
+			case TIMING_3D_FORMAT_SW_FRAME_PACKING:
+				info_packet->sb[5 + offset] = (0x0 << 4);
+				break;
 
-		case TIMING_3D_FORMAT_TOP_AND_BOTTOM:
-		case TIMING_3D_FORMAT_TB_SW_PACKED:
-			info_packet->sb[5] = (0x6 << 4);
-			break;
+			case TIMING_3D_FORMAT_SIDE_BY_SIDE:
+			case TIMING_3D_FORMAT_SBS_SW_PACKED:
+				info_packet->sb[5 + offset] = (0x8 << 4);
+				++length;
+				break;
 
-		default:
-			break;
-		}
+			case TIMING_3D_FORMAT_TOP_AND_BOTTOM:
+			case TIMING_3D_FORMAT_TB_SW_PACKED:
+				info_packet->sb[5 + offset] = (0x6 << 4);
+				break;
 
-		if (hdmi_vic_mode)
+			default:
+				break;
+			}
+
+		/* Doesn't need the offset as it can't be used with hf-vsif */
+		} else if (hdmi_vic_mode) {
+			info_packet->sb[4] = (1 << 5);
 			info_packet->sb[5] = stream->timing.hdmi_vic;
+		}
 
 		info_packet->hb0 = HDMI_INFOFRAME_TYPE_VENDOR;
 		info_packet->hb1 = 0x01;
-		info_packet->hb2 = (uint8_t) (length);
+		info_packet->hb2 = length & HDMI_INFOFRAME_LENGTH_MASK;
 
 		checksum += info_packet->hb0;
 		checksum += info_packet->hb1;