[PATCH] drm/i915/hdcp: Handle HDCP Line Rekeying for HDCP 1.4

[Suraj Kandpal]

TRANS_DDI_FUNC_CTL asks us to disable hdcp line rekeying when not in
hdcp 2.2 and we are not using an hdmi transcoder and it need to be
enabled when we are using an HDMI transcoder to enable HDCP 1.4.
We use intel_de_rmw cycles to update TRANS_DDI_FUNC_CTL register so
we cannot depend on the value being 0 by default everytime which calls
for seprate handling of HDCP 1.4 case.

--v2
-Use the exising function and modify it based on a bool rather than
have a different function [Matt]

--v3
-No need for kzalloc [Jani]

--v4
-i915_reg_t should not be pointer [Jani]
-use rekey_bit to ensure when writing to reg everything is initialized

Bspec: 69964, 50493, 50054
Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
---
 drivers/gpu/drm/i915/display/intel_hdcp.c | 37 ++++++++++++++---------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
index 4e937fbba4d2..dbcdd1777fa3 100644
--- a/drivers/gpu/drm/i915/display/intel_hdcp.c
+++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
@@ -32,27 +32,32 @@
 #define HDCP2_LC_RETRY_CNT			3
 
 static void
-intel_hdcp_disable_hdcp_line_rekeying(struct intel_encoder *encoder,
-				      struct intel_hdcp *hdcp)
+intel_hdcp_adjust_hdcp_line_rekeying(struct intel_encoder *encoder,
+				     struct intel_hdcp *hdcp,
+				     bool enable)
 {
 	struct intel_display *display = to_intel_display(encoder);
+	i915_reg_t rekey_reg;
+	u32 rekey_bit = 0;
 
 	/* Here we assume HDMI is in TMDS mode of operation */
 	if (encoder->type != INTEL_OUTPUT_HDMI)
 		return;
 
-	if (DISPLAY_VER(display) >= 30)
-		intel_de_rmw(display,
-			     TRANS_DDI_FUNC_CTL(display, hdcp->cpu_transcoder),
-			     0, XE3_TRANS_DDI_HDCP_LINE_REKEY_DISABLE);
-	else if (IS_DISPLAY_VERx100_STEP(display, 1401, STEP_B0, STEP_FOREVER) ||
-		 IS_DISPLAY_VERx100_STEP(display, 2000, STEP_B0, STEP_FOREVER))
-		intel_de_rmw(display,
-			     TRANS_DDI_FUNC_CTL(display, hdcp->cpu_transcoder),
-			     0, TRANS_DDI_HDCP_LINE_REKEY_DISABLE);
-	else if (IS_DISPLAY_VERx100_STEP(display, 1400, STEP_D0, STEP_FOREVER))
-		intel_de_rmw(display, MTL_CHICKEN_TRANS(hdcp->cpu_transcoder),
-			     0, HDCP_LINE_REKEY_DISABLE);
+	if (DISPLAY_VER(display) >= 30) {
+		rekey_reg = TRANS_DDI_FUNC_CTL(display, hdcp->cpu_transcoder);
+		rekey_bit = XE3_TRANS_DDI_HDCP_LINE_REKEY_DISABLE;
+	} else if (IS_DISPLAY_VERx100_STEP(display, 1401, STEP_B0, STEP_FOREVER) ||
+		   IS_DISPLAY_VERx100_STEP(display, 2000, STEP_B0, STEP_FOREVER)) {
+		rekey_reg = TRANS_DDI_FUNC_CTL(display, hdcp->cpu_transcoder);
+		rekey_bit = TRANS_DDI_HDCP_LINE_REKEY_DISABLE;
+	} else if (IS_DISPLAY_VERx100_STEP(display, 1400, STEP_D0, STEP_FOREVER)) {
+		rekey_reg = MTL_CHICKEN_TRANS(hdcp->cpu_transcoder);
+		rekey_bit = HDCP_LINE_REKEY_DISABLE;
+	}
+
+	if (rekey_bit)
+		intel_de_rmw(display, rekey_reg, rekey_bit, enable ? 0 : rekey_bit);
 }
 
 static int intel_conn_to_vcpi(struct intel_atomic_state *state,
@@ -1049,6 +1054,8 @@ static int intel_hdcp1_enable(struct intel_connector *connector)
 		return ret;
 	}
 
+	intel_hdcp_adjust_hdcp_line_rekeying(connector->encoder, hdcp, true);
+
 	/* Incase of authentication failures, HDCP spec expects reauth. */
 	for (i = 0; i < tries; i++) {
 		ret = intel_hdcp_auth(connector);
@@ -2062,7 +2069,7 @@ static int _intel_hdcp2_enable(struct intel_atomic_state *state,
 		    connector->base.base.id, connector->base.name,
 		    hdcp->content_type);
 
-	intel_hdcp_disable_hdcp_line_rekeying(connector->encoder, hdcp);
+	intel_hdcp_adjust_hdcp_line_rekeying(connector->encoder, hdcp, false);
 
 	ret = hdcp2_authenticate_and_encrypt(state, connector);
 	if (ret) {
-- 
2.34.1