[PATCH] tests/intel/xe_configfs: Use available engine for ctx-restore subtests

[Nitin Gote <nitin.r.gote@intel.com>]

The ctx-restore-post-bb and ctx-restore-mid-bb subtests were hardcoded
to use the "rcs" engine class. Platforms without a render engine (e.g.
PVC, CRI) fail because the batch buffer is never injected into any
engine's LRC, causing register readback to fail.

Fix it by dynamically detecting an available engine, prefer render
("rcs") when available, otherwise fall back to compute ("ccs").
Every xe platform has at least one of these engine classes.
Remove the hardcoded "rcs" from test data and add the detected
engine name at runtime.

v4: Short igt_require_f message, add blank lines for readability (Kamil)
v3: Add break after the ccs for consistency, so the loop exits
    as soon as a usable engine is picked regardless of class
    iteration order (Stuart)
v2: Add igt_require_f(engine, "explanation\n") (Kamil)

Fixes: b6abdc26e01b ("tests/intel/xe_configfs: Check ctx_restore_post_bb")
Cc: Marcin Bernatowicz <marcin.bernatowicz@linux.intel.com>
Cc: Kamil Konieczny <kamil.konieczny@linux.intel.com>
Cc: Stuart Summers <stuart.summers@intel.com>
Reviewed-by: Kamil Konieczny <kamil.konieczny@linux.intel.com>
Signed-off-by: Nitin Gote <nitin.r.gote@intel.com>
---
 tests/intel/xe_configfs.c | 67 +++++++++++++++++++++++++++------------
 1 file changed, 47 insertions(+), 20 deletions(-)

diff --git a/tests/intel/xe_configfs.c b/tests/intel/xe_configfs.c
index 39762e030..e7c797eb7 100644
--- a/tests/intel/xe_configfs.c
+++ b/tests/intel/xe_configfs.c
@@ -265,11 +265,12 @@ static void test_ctx_restore_invalid(int configfs_device_fd, const char *type)
  * SUBTEST: ctx-restore-mid-bb
  * Description: Validate ctx_restore_mid_bb attribute
  */
-static void test_ctx_restore(int configfs_device_fd, const char *type)
+static void test_ctx_restore(int configfs_device_fd, const char *type,
+			     const char *engine)
 {
 	static const struct value {
 		const char *test;
-		const char *in;
+		const char *in[3];
 		const char *out;
 		uint32_t reg[4];
 		uint32_t reg_val[4];
@@ -280,41 +281,45 @@ static void test_ctx_restore(int configfs_device_fd, const char *type)
 		 * previous execution set a specific value in the HW
 		 */
 		{ .test = "cmd-single",
-		  .in = "rcs cmd 11000001 4F100 DEA0BEE0",
-		  .out = "rcs: 11000001 0004f100 dea0bee0\n",
+		  .in = { "cmd 11000001 4F100 DEA0BEE0" },
+		  .out = "11000001 0004f100 dea0bee0",
 		  .reg = { 0x4f100 },
 		  .reg_val = { 0xdea0bee0 },
 		},
 		{ .test = "cmd-single-multi-values",
-		  .in = "rcs cmd 11000003 4F100 DEA1BEE1 4F104 DEA2BEE2",
-		  .out = "rcs: 11000003 0004f100 dea1bee1 0004f104 dea2bee2\n",
+		  .in = { "cmd 11000003 4F100 DEA1BEE1 4F104 DEA2BEE2" },
+		  .out = "11000003 0004f100 dea1bee1 0004f104 dea2bee2",
 		  .reg = { 0x4f100, 0x4f104 },
 		  .reg_val = { 0xdea1bee1, 0xdea2bee2 },
 		},
 		{ .test = "cmd-multi",
-		  .in = "rcs cmd 11000001 4F100 DEA3BEE3\n"
-			"rcs cmd 11000001 4F104 DEA4BEE4",
-		  .out = "rcs: 11000001 0004f100 dea3bee3 11000001 0004f104 dea4bee4\n",
+		  .in = { "cmd 11000001 4F100 DEA3BEE3",
+			  "cmd 11000001 4F104 DEA4BEE4" },
+		  .out = "11000001 0004f100 dea3bee3 11000001 0004f104 dea4bee4",
 		  .reg = { 0x4f100, 0x4f104 },
 		  .reg_val = { 0xdea3bee3, 0xdea4bee4 },
 		},
 		{ .test = "reg-single",
-		  .in = "rcs reg 4F100 DEA5BEE5",
-		  .out = "rcs: 11000001 0004f100 dea5bee5\n",
+		  .in = { "reg 4F100 DEA5BEE5" },
+		  .out = "11000001 0004f100 dea5bee5",
 		  .reg = { 0x4f100 },
 		  .reg_val = { 0xdea5bee5 },
 		},
 		{ .test = "reg-multi",
-		  .in = "rcs reg 4F100 DEA6BEE6\n"
-			"rcs reg 4F104 DEA7BEE7",
-		  .out = "rcs: 11000001 0004f100 dea6bee6 11000001 0004f104 dea7bee7\n",
+		  .in = { "reg 4F100 DEA6BEE6",
+			  "reg 4F104 DEA7BEE7" },
+		  .out = "11000001 0004f100 dea6bee6 11000001 0004f104 dea7bee7",
 		  .reg = { 0x4f100, 0x4f104 },
 		  .reg_val = { 0xdea6bee6, 0xdea7bee7 },
 		},
 	};
+	char in[4096] = { };
+	char out[4096] = { };
 	char buf[4096] = { };
 	char file[64] = { };
 
+	igt_require_f(engine, "No render nor compute engine available\n");
+
 	snprintf(file, sizeof(file), "ctx_restore_%s_bb", type);
 
 	for (size_t i = 0; i < ARRAY_SIZE(values); i++) {
@@ -323,14 +328,20 @@ static void test_ctx_restore(int configfs_device_fd, const char *type)
 		igt_audio_driver_unload(NULL);
 		igt_kmod_unbind("xe", bus_addr);
 
+		for (int j = 0, off = 0; v->in[j]; j++)
+			off += snprintf(in + off, sizeof(in) - off, "%s %s\n",
+					engine, v->in[j]);
+
+		snprintf(out, sizeof(out), "%s: %s\n", engine, v->out);
+
 		igt_info("Test %s\n", v->test);
-		igt_debug("bb '%s'\n", v->in);
-		igt_assert(igt_sysfs_set(configfs_device_fd, file, v->in));
+		igt_debug("bb '%s'\n", in);
+		igt_assert(igt_sysfs_set(configfs_device_fd, file, in));
 
 		igt_assert(igt_sysfs_read(configfs_device_fd, file, buf,
 					  sizeof(buf) - 1));
-		if (strcmp(v->out, buf)) {
-			igt_debug("Expecting '%s' but found '%s'\n", v->out, buf);
+		if (strcmp(out, buf)) {
+			igt_debug("Expecting '%s' but found '%s'\n", out, buf);
 			igt_fail(IGT_EXIT_FAILURE);
 		}
 
@@ -368,12 +379,28 @@ int igt_main()
 	int fd, configfs_fd, configfs_device_fd;
 	uint32_t devid;
 	bool is_vf_device;
+	const char *engine = NULL;
 
 	igt_fixture() {
+		struct drm_xe_engine_class_instance *hwe;
+
 		fd = drm_open_driver(DRIVER_XE);
 		devid = intel_get_drm_devid(fd);
 		is_vf_device = intel_is_vf_device(fd);
 		set_bus_addr(fd);
+
+		xe_for_each_engine(fd, hwe) {
+			if (hwe->engine_class == DRM_XE_ENGINE_CLASS_RENDER) {
+				engine = "rcs";
+				break;
+			}
+
+			if (!engine && hwe->engine_class == DRM_XE_ENGINE_CLASS_COMPUTE) {
+				engine = "ccs";
+				break;
+			}
+		}
+
 		drm_close_driver(fd);
 
 		configfs_fd = igt_configfs_open("xe");
@@ -423,7 +450,7 @@ int igt_main()
 	igt_subtest("ctx-restore-post-bb") {
 		igt_skip_on_f(is_vf_device, "MMIO register readback not possible on VF\n");
 		configfs_device_fd = create_device_configfs_group(configfs_fd);
-		test_ctx_restore(configfs_device_fd, "post");
+		test_ctx_restore(configfs_device_fd, "post", engine);
 		close_configfs_group(configfs_fd, configfs_device_fd);
 	}
 
@@ -439,7 +466,7 @@ int igt_main()
 	igt_subtest("ctx-restore-mid-bb") {
 		igt_skip_on_f(is_vf_device, "MMIO register readback not possible on VF\n");
 		configfs_device_fd = create_device_configfs_group(configfs_fd);
-		test_ctx_restore(configfs_device_fd, "mid");
+		test_ctx_restore(configfs_device_fd, "mid", engine);
 		close_configfs_group(configfs_fd, configfs_device_fd);
 	}
 
-- 
2.50.1