[PATCH v3 i-g-t] lib/drmtest: load forced module

[Kamil Konieczny]

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

Special case is VGEM which should always be loaded as itself.

v2: fixed typo, added r-b (Lukasz)
    rebase (Kamil)
v3: moved info about VGEM to end od description (Kamil)

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

diff --git a/lib/drmtest.c b/lib/drmtest.c
index c98754798..52b5a2020 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.
@@ -263,7 +283,7 @@ int __drm_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);
@@ -280,18 +300,7 @@ int __drm_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);
@@ -375,16 +384,34 @@ 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);
 }
-- 
2.42.0