Opening drm card may end up in loading kernel module. Take into
account forced driver set by IGT_FORCE_DRIVER and load that one.
If forced is in known ones, use function for loading it
otherwise load it only when requested was DRIVER_ANY. Special
case is VGEM which should alwayes be loaded as itself. It can

end up in not loading any module in case when igt test requested
specific one, for example i915 but forced is different.

Cc: Rob Clark <robdclark@gmail.com>
Cc: Rob Clark <robdclark@chromium.org>
Cc: Helen Koike <helen.koike@collabora.com>
Cc: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Signed-off-by: Kamil Konieczny <kamil.konieczny@linux.intel.com>
---
 lib/drmtest.c | 65 ++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 46 insertions(+), 19 deletions(-)

diff --git a/lib/drmtest.c b/lib/drmtest.c
index f0b97e362..b524a9eb3 100644
--- a/lib/drmtest.c
+++ b/lib/drmtest.c
@@ -221,6 +221,26 @@ struct _opened_device_path {
 	struct igt_list_head link;
 };
 
+static void modulename_to_chipset(const char *name, unsigned int *chip)
+{
+	if (!name)
+		return;
+
+	for (int start = 0, end = ARRAY_SIZE(modules) - 1; start < end; ) {
+		int mid = start + (end - start) / 2;
+		int ret = strcmp(modules[mid].module, name);
+
+		if (ret < 0) {
+			start = mid + 1;
+		} else if (ret > 0) {
+			end = mid;
+		} else {
+			*chip = modules[mid].bit;
+			break;
+		}
+	}
+}
+
 /*
  * Logs path of opened device. Device path opened for the first time is logged at info level,
  * subsequent opens (if any) are logged at debug level.
@@ -249,7 +269,7 @@ static int open_device(const char *name, unsigned int chipset)
 {
 	const char *forced;
 	char dev_name[16] = "";
-	int chip = DRIVER_ANY;
+	unsigned int chip = DRIVER_ANY;
 	int fd;
 
 	fd = open(name, O_RDWR);
@@ -266,18 +286,7 @@ static int open_device(const char *name, unsigned int chipset)
 		goto err;
 	}
 
-	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);
-		if (ret < 0) {
-			start = mid + 1;
-		} else if (ret > 0) {
-			end = mid;
-		} else {
-			chip = modules[mid].bit;
-			break;
-		}
-	}
+	modulename_to_chipset(dev_name, &chip);
 
 	if ((chipset & chip) == chip) {
 		log_opened_device_path(name);
@@ -361,16 +370,34 @@ static int __search_and_open(const char *base, int offset, unsigned int chipset,
 void drm_load_module(unsigned int chipset)
 {
 	static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+	const char *forced = forced_driver();
+	unsigned int chip = 0;
+	bool want_any = chipset == DRIVER_ANY;
+
+	if (forced) {
+		if (chipset == DRIVER_VGEM)
+			chip = DRIVER_VGEM; /* ignore forced */
+		else
+			modulename_to_chipset(forced, &chip);
+
+		chipset &= chip; /* forced can be in known modules */
+	}
 
 	pthread_mutex_lock(&mutex);
-	for (const struct module *m = modules; m->module; m++) {
-		if (chipset & m->bit) {
-			if (m->modprobe)
-				m->modprobe(m->module);
-			else
-				modprobe(m->module);
+	if (forced && chipset == 0) {
+		if (want_any)
+			modprobe(forced);
+	} else {
+		for (const struct module *m = modules; m->module; m++) {
+			if (chipset & m->bit) {
+				if (m->modprobe)
+					m->modprobe(m->module);
+				else
+					modprobe(m->module);
+			}
 		}
 	}
+
 	pthread_mutex_unlock(&mutex);
 	igt_devices_scan(true);
 }