drm/i915: add DP test request handling

DPCD 1.1+ adds some automated test infrastructure support.  Add support
for reading the IRQ source and jumping to a test handling routine if
needed.  Subsequent patches will handle particular tests; this patch
just ACKs any requested tests by default.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Keith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/intel_dp.c

@@ -1776,6 +1776,27 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 	return false;
 }
 
+static bool
+intel_dp_get_sink_irq(struct intel_dp *intel_dp, u8 *sink_irq_vector)
+{
+	int ret;
+
+	ret = intel_dp_aux_native_read_retry(intel_dp,
+					     DP_DEVICE_SERVICE_IRQ_VECTOR,
+					     sink_irq_vector, 1);
+	if (!ret)
+		return false;
+
+	return true;
+}
+
+static void
+intel_dp_handle_test_request(struct intel_dp *intel_dp)
+{
+	/* NAK by default */
+	intel_dp_aux_native_write_1(intel_dp, DP_TEST_RESPONSE, DP_TEST_ACK);
+}
+
 /*
  * According to DP spec
  * 5.1.2:
@@ -1788,6 +1809,8 @@ intel_dp_get_dpcd(struct intel_dp *intel_dp)
 static void
 intel_dp_check_link_status(struct intel_dp *intel_dp)
 {
+	u8 sink_irq_vector;
+
 	if (intel_dp->dpms_mode != DRM_MODE_DPMS_ON)
 		return;
 
@@ -1806,6 +1829,20 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
 		return;
 	}
 
+	/* Try to read the source of the interrupt */
+	if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
+	    intel_dp_get_sink_irq(intel_dp, &sink_irq_vector)) {
+		/* Clear interrupt source */
+		intel_dp_aux_native_write_1(intel_dp,
+					    DP_DEVICE_SERVICE_IRQ_VECTOR,
+					    sink_irq_vector);
+
+		if (sink_irq_vector & DP_AUTOMATED_TEST_REQUEST)
+			intel_dp_handle_test_request(intel_dp);
+		if (sink_irq_vector & (DP_CP_IRQ | DP_SINK_SPECIFIC_IRQ))
+			DRM_DEBUG_DRIVER("CP or sink specific irq unhandled\n");
+	}
+
 	if (!intel_channel_eq_ok(intel_dp)) {
 		DRM_DEBUG_KMS("%s: channel EQ not ok, retraining\n",
 			      drm_get_encoder_name(&intel_dp->base.base));

include/drm/drm_dp_helper.h

@@ -153,6 +153,12 @@
 # define DP_PSR_CRC_VERIFICATION	    (1 << 2)
 # define DP_PSR_FRAME_CAPTURE		    (1 << 3)
 
+#define DP_DEVICE_SERVICE_IRQ_VECTOR	    0x201
+# define DP_REMOTE_CONTROL_COMMAND_PENDING  (1 << 0)
+# define DP_AUTOMATED_TEST_REQUEST	    (1 << 1)
+# define DP_CP_IRQ			    (1 << 2)
+# define DP_SINK_SPECIFIC_IRQ		    (1 << 6)
+
 #define DP_LANE0_1_STATUS		    0x202
 #define DP_LANE2_3_STATUS		    0x203
 # define DP_LANE_CR_DONE		    (1 << 0)
@@ -185,6 +191,25 @@
 # define DP_ADJUST_PRE_EMPHASIS_LANE1_MASK   0xc0
 # define DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT  6
 
+#define DP_TEST_REQUEST			    0x218
+# define DP_TEST_LINK_TRAINING		    (1 << 0)
+# define DP_TEST_LINK_PATTERN		    (1 << 1)
+# define DP_TEST_LINK_EDID_READ		    (1 << 2)
+# define DP_TEST_LINK_PHY_TEST_PATTERN	    (1 << 3) /* DPCD >= 1.1 */
+
+#define DP_TEST_LINK_RATE		    0x219
+# define DP_LINK_RATE_162		    (0x6)
+# define DP_LINK_RATE_27		    (0xa)
+
+#define DP_TEST_LANE_COUNT		    0x220
+
+#define DP_TEST_PATTERN			    0x221
+
+#define DP_TEST_RESPONSE		    0x260
+# define DP_TEST_ACK			    (1 << 0)
+# define DP_TEST_NAK			    (1 << 1)
+# define DP_TEST_EDID_CHECKSUM_WRITE	    (1 << 2)
+
 #define DP_SET_POWER                        0x600
 # define DP_SET_POWER_D0                    0x1
 # define DP_SET_POWER_D3                    0x2