drm/dp_mst: Move test_calc_pbn_mode() into an actual selftest

Yes, apparently we've been testing this for every single driver load for
quite a long time now. At least that means our PBN calculation is solid!

Anyway, introduce self tests for MST and move this into there.

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-5-lyude@redhat.com

drivers/gpu/drm/drm_dp_mst_topology.c

@@ -47,7 +47,6 @@
  */
 static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
 				  char *buf);
-static int test_calc_pbn_mode(void);
 
 static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port);
 
@@ -3578,30 +3577,6 @@ int drm_dp_calc_pbn_mode(int clock, int bpp)
 }
 EXPORT_SYMBOL(drm_dp_calc_pbn_mode);
 
-static int test_calc_pbn_mode(void)
-{
-	int ret;
-	ret = drm_dp_calc_pbn_mode(154000, 30);
-	if (ret != 689) {
-		DRM_ERROR("PBN calculation test failed - clock %d, bpp %d, expected PBN %d, actual PBN %d.\n",
-				154000, 30, 689, ret);
-		return -EINVAL;
-	}
-	ret = drm_dp_calc_pbn_mode(234000, 30);
-	if (ret != 1047) {
-		DRM_ERROR("PBN calculation test failed - clock %d, bpp %d, expected PBN %d, actual PBN %d.\n",
-				234000, 30, 1047, ret);
-		return -EINVAL;
-	}
-	ret = drm_dp_calc_pbn_mode(297000, 24);
-	if (ret != 1063) {
-		DRM_ERROR("PBN calculation test failed - clock %d, bpp %d, expected PBN %d, actual PBN %d.\n",
-				297000, 24, 1063, ret);
-		return -EINVAL;
-	}
-	return 0;
-}
-
 /* we want to kick the TX after we've ack the up/down IRQs. */
 static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr)
 {
@@ -3979,8 +3954,6 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
 	if (!mgr->proposed_vcpis)
 		return -ENOMEM;
 	set_bit(0, &mgr->payload_mask);
-	if (test_calc_pbn_mode() < 0)
-		DRM_ERROR("MST PBN self-test failed\n");
 
 	mst_state = kzalloc(sizeof(*mst_state), GFP_KERNEL);
 	if (mst_state == NULL)

drivers/gpu/drm/selftests/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
 test-drm_modeset-y := test-drm_modeset_common.o test-drm_plane_helper.o \
                       test-drm_format.o test-drm_framebuffer.o \
-		      test-drm_damage_helper.o
+		      test-drm_damage_helper.o test-drm_dp_mst_helper.o
 
 obj-$(CONFIG_DRM_DEBUG_SELFTEST) += test-drm_mm.o test-drm_modeset.o test-drm_cmdline_parser.o

drivers/gpu/drm/selftests/drm_modeset_selftests.h

@@ -32,3 +32,4 @@ selftest(damage_iter_damage_one_intersect, igt_damage_iter_damage_one_intersect)
 selftest(damage_iter_damage_one_outside, igt_damage_iter_damage_one_outside)
 selftest(damage_iter_damage_src_moved, igt_damage_iter_damage_src_moved)
 selftest(damage_iter_damage_not_visible, igt_damage_iter_damage_not_visible)
+selftest(dp_mst_calc_pbn_mode, igt_dp_mst_calc_pbn_mode)

drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Test cases for for the DRM DP MST helpers
+ */
+
+#include <drm/drm_dp_mst_helper.h>
+#include <drm/drm_print.h>
+
+#include "test-drm_modeset_common.h"
+
+int igt_dp_mst_calc_pbn_mode(void *ignored)
+{
+	int pbn, i;
+	const struct {
+		int rate;
+		int bpp;
+		int expected;
+	} test_params[] = {
+		{ 154000, 30, 689 },
+		{ 234000, 30, 1047 },
+		{ 297000, 24, 1063 },
+	};
+
+	for (i = 0; i < ARRAY_SIZE(test_params); i++) {
+		pbn = drm_dp_calc_pbn_mode(test_params[i].rate,
+					   test_params[i].bpp);
+		FAIL(pbn != test_params[i].expected,
+		     "Expected PBN %d for clock %d bpp %d, got %d\n",
+		     test_params[i].expected, test_params[i].rate,
+		     test_params[i].bpp, pbn);
+	}
+
+	return 0;
+}

drivers/gpu/drm/selftests/test-drm_modeset_common.h

@@ -39,5 +39,6 @@ int igt_damage_iter_damage_one_intersect(void *ignored);
 int igt_damage_iter_damage_one_outside(void *ignored);
 int igt_damage_iter_damage_src_moved(void *ignored);
 int igt_damage_iter_damage_not_visible(void *ignored);
+int igt_dp_mst_calc_pbn_mode(void *ignored);
 
 #endif