drm/i915: Clear the repeater bit on HDCP disable

On HDCP disable, clear the repeater bit. This ensures if we connect a
non-repeater sink after a repeater, the bit is in the state we expect.

Fixes: ee5e5e7a ("drm/i915: Add HDCP framework + base implementation")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ramalingam C <ramalingam.c@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: intel-gfx@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v4.17+
Reviewed-by: Ramalingam C <ramalingam.c@intel.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200818153910.27894-3-sean@poorly.run
(cherry picked from commit 2cc0c7b5)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/display/intel_hdcp.c

@@ -795,6 +795,7 @@ static int _intel_hdcp_disable(struct intel_connector *connector)
 	struct intel_hdcp *hdcp = &connector->hdcp;
 	enum port port = dig_port->base.port;
 	enum transcoder cpu_transcoder = hdcp->cpu_transcoder;
+	u32 repeater_ctl;
 	int ret;
 
 	drm_dbg_kms(&dev_priv->drm, "[%s:%d] HDCP is being disabled...\n",
@@ -810,6 +811,11 @@ static int _intel_hdcp_disable(struct intel_connector *connector)
 		return -ETIMEDOUT;
 	}
 
+	repeater_ctl = intel_hdcp_get_repeater_ctl(dev_priv, cpu_transcoder,
+						   port);
+	intel_de_write(dev_priv, HDCP_REP_CTL,
+		       intel_de_read(dev_priv, HDCP_REP_CTL) & ~repeater_ctl);
+
 	ret = hdcp->shim->toggle_signalling(dig_port, false);
 	if (ret) {
 		drm_err(&dev_priv->drm, "Failed to disable HDCP signalling\n");