lib: Refactor common detection of missed interrupts

As we have the same function in a few places to read the
debugfs/i915_ring_missed_irq file, move it to the core.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

lib/igt_gt.c

@@ -501,3 +501,35 @@ void igt_clflush_range(void *addr, int size)
 		asm volatile("clflush %0" : "+m" (*(volatile char *)p));
 	asm volatile("mfence" ::: "memory");
 }
+
+/**
+ * intel_detect_and_clear_missed_irq:
+ * @fd: open i915 drm file descriptor, used to quiesce the gpu
+ *
+ * This functions idles the GPU and then queries whether there has
+ * been a missed interrupt reported by the driver. Afterwards it
+ * clears the missed interrupt flag, in order to disable the timer
+ * fallback for the next test.
+ */
+unsigned intel_detect_and_clear_missed_interrupts(int fd)
+{
+	unsigned missed = 0;
+	FILE *file;
+
+	gem_quiescent_gpu(fd);
+
+	file = igt_debugfs_fopen("i915_ring_missed_irq", "r");
+	if (file) {
+		igt_assert(fscanf(file, "%x", &missed) == 1);
+		fclose(file);
+	}
+	if (missed) {
+		file = igt_debugfs_fopen("i915_ring_missed_irq", "w");
+		if (file) {
+			fwrite("0\n", 1, 2, file);
+			fclose(file);
+		}
+	}
+
+	return missed;
+}

lib/igt_gt.h

@@ -89,4 +89,6 @@ enum stop_ring_flags igt_get_stop_rings(void);
 int igt_setup_clflush(void);
 void igt_clflush_range(void *addr, int size);
 
+unsigned intel_detect_and_clear_missed_interrupts(int fd);
+
 #endif /* IGT_GT_H */

tests/gem_concurrent_all.c

@@ -755,26 +755,6 @@ static struct igt_hang_ring rcs_hang(void)
 	return igt_hang_ring(fd, I915_EXEC_RENDER);
 }
 
-static void check_gpu(void)
-{
-	unsigned missed_irq = 0;
-	FILE *file;
-
-	gem_quiescent_gpu(fd);
-
-	file = igt_debugfs_fopen("i915_ring_missed_irq", "r");
-	if (file) {
-		fscanf(file, "%x", &missed_irq);
-		fclose(file);
-	}
-	file = igt_debugfs_fopen("i915_ring_missed_irq", "w");
-	if (file) {
-		fwrite("0\n", 1, 2, file);
-		fclose(file);
-	}
-	igt_assert_eq(missed_irq, 0);
-}
-
 static void do_basic0(struct buffers *buffers,
 		      do_copy do_copy_func,
 		      do_hang do_hang_func)
@@ -1135,7 +1115,7 @@ static void run_single(struct buffers *buffers,
 		       do_hang do_hang_func)
 {
 	do_test_func(buffers, do_copy_func, do_hang_func);
-	check_gpu();
+	igt_assert_eq(intel_detect_and_clear_missed_interrupts(fd), 0);
 }
 
 static void run_interruptible(struct buffers *buffers,
@@ -1146,7 +1126,7 @@ static void run_interruptible(struct buffers *buffers,
 	for (pass = 0; pass < 10; pass++)
 		do_test_func(buffers, do_copy_func, do_hang_func);
 	pass = 0;
-	check_gpu();
+	igt_assert_eq(intel_detect_and_clear_missed_interrupts(fd), 0);
 }
 
 static void __run_forked(struct buffers *buffers,
@@ -1177,7 +1157,7 @@ static void __run_forked(struct buffers *buffers,
 	}
 
 	igt_waitchildren();
-	check_gpu();
+	igt_assert_eq(intel_detect_and_clear_missed_interrupts(fd), 0);
 
 	num_buffers = old_num_buffers;
 }
@@ -1473,6 +1453,7 @@ igt_main
 
 	igt_fixture {
 		fd = drm_open_driver(DRIVER_INTEL);
+		intel_detect_and_clear_missed_interrupts(fd);
 		devid = intel_get_drm_devid(fd);
 		gen = intel_gen(devid);
 		rendercopy = igt_get_render_copyfunc(devid);

tests/gem_ring_sync_loop.c

@@ -91,39 +91,16 @@ sync_loop(int fd)
 	gem_close(fd, object[0].handle);
 }
 
-static unsigned intel_detect_and_clear_missed_irq(int fd)
-{
-	unsigned missed = 0;
-	FILE *file;
-
-	gem_quiescent_gpu(fd);
-
-	file = igt_debugfs_fopen("i915_ring_missed_irq", "r");
-	if (file) {
-		igt_assert(fscanf(file, "%x", &missed) == 1);
-		fclose(file);
-	}
-	if (missed) {
-		file = igt_debugfs_fopen("i915_ring_missed_irq", "w");
-		if (file) {
-			fwrite("0\n", 1, 2, file);
-			fclose(file);
-		}
-	}
-
-	return missed;
-}
-
 igt_simple_main
 {
 	int fd;
 
 	fd = drm_open_driver(DRIVER_INTEL);
 	igt_require(gem_get_num_rings(fd) > 1);
-	intel_detect_and_clear_missed_irq(fd); /* clear before we begin */
+	intel_detect_and_clear_missed_interrupts(fd);
 
 	sync_loop(fd);
 
-	igt_assert_eq(intel_detect_and_clear_missed_irq(fd), 0);
+	igt_assert_eq(intel_detect_and_clear_missed_interrupts(fd), 0);
 	close(fd);
 }

tests/gem_sync.c

@@ -33,29 +33,6 @@ IGT_TEST_DESCRIPTION("Basic check of ring<->ring write synchronisation.");
  * Extremely efficient at catching missed irqs
  */
 
-static unsigned intel_detect_and_clear_missed_irq(int fd)
-{
-	unsigned missed = 0;
-	FILE *file;
-
-	gem_quiescent_gpu(fd);
-
-	file = igt_debugfs_fopen("i915_ring_missed_irq", "r");
-	if (file) {
-		igt_assert(fscanf(file, "%x", &missed) == 1);
-		fclose(file);
-	}
-	if (missed) {
-		file = igt_debugfs_fopen("i915_ring_missed_irq", "w");
-		if (file) {
-			fwrite("0\n", 1, 2, file);
-			fclose(file);
-		}
-	}
-
-	return missed;
-}
-
 static double gettime(void)
 {
 	static clockid_t clock = -1;
@@ -105,7 +82,7 @@ sync_ring(int fd, int ring, unsigned flags)
 	double start, elapsed;
 	unsigned long cycles;
 
-	intel_detect_and_clear_missed_irq(fd); /* clear before we begin */
+	intel_detect_and_clear_missed_interrupts(fd);
 
 	memset(&object, 0, sizeof(object));
 	object.handle = gem_create(fd, 4096);
@@ -130,7 +107,7 @@ sync_ring(int fd, int ring, unsigned flags)
 	igt_info("Completed %ld cycles: %.3f us\n", cycles, elapsed*1e6/cycles);
 
 	gem_close(fd, object.handle);
-	igt_assert_eq(intel_detect_and_clear_missed_irq(fd), 0);
+	igt_assert_eq(intel_detect_and_clear_missed_interrupts(fd), 0);
 }
 
 igt_main