[igt-dev] [PATCH i-g-t v3] Add support for forcing a specific driver

[Petri Latvala]

This commit adds a new option for forcing the use of a specific driver
indicated via an environment variable.

v2 (Petri):
 - Use an environment variable instead of command line
 - Refactor the loop in __open_device
 - Don't try to load kernel modules

v3 (Petri):
 - Rebase and adjust to the driver loading changes

Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo at gmail.com>
Signed-off-by: Petri Latvala <petri.latvala at intel.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Arkadiusz Hiler <arkadiusz.hiler at intel.com>
Cc: gustavo at padovan.org
Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch> #v2
---
 lib/drmtest.c  | 32 ++++++++++++++++++++++++++++++++
 lib/drmtest.h  |  2 ++
 lib/igt_core.c |  5 +++++
 3 files changed, 39 insertions(+)

diff --git a/lib/drmtest.c b/lib/drmtest.c
index d2aa1c19..35914c50 100644
--- a/lib/drmtest.c
+++ b/lib/drmtest.c
@@ -123,6 +123,31 @@ static bool has_known_intel_chipset(int fd)
 	return true;
 }
 
+static char _forced_driver[16] = "";
+
+/**
+ * __set_forced_driver:
+ * @name: name of driver to forcibly use
+ *
+ * Set the name of a driver to use when calling #drm_open_driver with
+ * the #DRIVER_ANY flag.
+ */
+void __set_forced_driver(const char *name)
+{
+	if (!name)
+		igt_warn("No driver specified, keep default behaviour\n");
+
+	strncpy(_forced_driver, name, sizeof(_forced_driver) - 1);
+}
+
+static const char *forced_driver(void)
+{
+	if (_forced_driver[0])
+		return _forced_driver;
+
+	return NULL;
+}
+
 #define LOCAL_I915_EXEC_VEBOX	(4 << 0)
 /**
  * gem_quiescent_gpu:
@@ -212,6 +237,7 @@ static const struct module {
 
 static int open_device(const char *name, unsigned int chipset)
 {
+	const char *forced;
 	char dev_name[16] = "";
 	int chip = DRIVER_ANY;
 	int fd;
@@ -223,6 +249,12 @@ static int open_device(const char *name, unsigned int chipset)
 	if (__get_drm_device_name(fd, dev_name, sizeof(dev_name) - 1) == -1)
 		goto err;
 
+	forced = forced_driver();
+	if (forced && chipset == DRIVER_ANY && !strcmp(forced, dev_name)) {
+		igt_debug("Force option used: Using driver %s\n", dev_name);
+		return fd;
+	}
+
 	for (int start = 0, end = ARRAY_SIZE(modules) - 1; start < end; ){
 		int mid = start + (end - start) / 2;
 		int ret = strcmp(modules[mid].module, dev_name);
diff --git a/lib/drmtest.h b/lib/drmtest.h
index 96ee517e..8743b1bb 100644
--- a/lib/drmtest.h
+++ b/lib/drmtest.h
@@ -52,6 +52,8 @@
  */
 #define DRIVER_ANY 	~(DRIVER_VGEM)
 
+void __set_forced_driver(const char *name);
+
 /**
  * ARRAY_SIZE:
  * @arr: static array
diff --git a/lib/igt_core.c b/lib/igt_core.c
index 64883d64..50d6008f 100644
--- a/lib/igt_core.c
+++ b/lib/igt_core.c
@@ -647,6 +647,11 @@ static void common_init_env(void)
 	igt_frame_dump_path = getenv("IGT_FRAME_DUMP_PATH");
 
 	stderr_needs_sentinel = getenv("IGT_SENTINEL_ON_STDERR") != NULL;
+
+	env = getenv("IGT_FORCE_DRIVER");
+	if (env) {
+		__set_forced_driver(env);
+	}
 }
 
 static int common_init(int *argc, char **argv,
-- 
2.19.1