[PATCH i-g-t v3] lib/drmtest: drop legacy path from filtered opens

[Kamil Konieczny]

For some multi-GPU tests user can check them on single-GPU board
with the help of repeating same card in --device option or
environment var IGT_DEVICE:

sudo IGT_DEVICE=pci:vendor=Intel,card=0\;pci:vendor=Intel,card=0 \
	build/tests/gem_basic --r multigpu-create-close

but is unable to use it due to current implementation of device
opening in function __drm_open_driver_another(). It will also
prevent restricting multiGPU test to only two cards on three or
four card board.

To allow this separate legacy opening path from filtered one and
do not fallback into legacy path when index for card exceeds
number of filtered devices. Use local opened fds table only for
legacy opens so that path is not affected.
When filters are used for multi-GPU tests user should provide all
of them needed for testing, this could be done with the help of
incrementing filters or with "card=all":

sudo IGT_DEVICE=pci:vendor=Intel,card=all \
	build/tests/gem_basic --r multigpu-create-close

v2: improving description, using filtered_count var (Janusz)
  changing drmtest: to lib/drmtest: (Kamil)
  adding Lukasz Laguna to Cc: (Kamil)
v3: for out-of-bound index print debug, not a warning (Kamil)

Cc: Arkadiusz Hiler <arek at hiler.eu>
Cc: Chris Wilson <chris.p.wilson at linux.intel.com>
Cc: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>
Cc: Lukasz Laguna <lukasz.laguna at intel.com>
Cc: Petri Latvala <adrinael at adrinael.net>
Cc: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
Signed-off-by: Kamil Konieczny <kamil.konieczny at linux.intel.com>
Reviewed-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
Reviewed-by: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>
---
 lib/drmtest.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/lib/drmtest.c b/lib/drmtest.c
index 52b5a2020..298cda2c5 100644
--- a/lib/drmtest.c
+++ b/lib/drmtest.c
@@ -481,13 +481,12 @@ static bool __get_card_for_nth_filter(int idx, struct igt_device_card *card)
  *
  * This function opens device in the following order:
  *
- * 1. when --device arguments are present:
+ * 1. when --device arguments are present or IGT_DEVICE env var is used:
  *   * device scanning is executed,
  *   * idx-th filter (starting with 0, filters are semicolon separated) is used
- *   * if there is no idx-th filter, goto 2
+ *   * if there is no idx-th filter fail with -1
  *   * first device maching the filter is selected
- *   * if it's already opened (for indexes = 0..idx-1) we fail with -1
- *   * otherwise open the device and return the fd
+ *   * open the device and return the fd
  *
  * 2. compatibility mode - open the first DRM device we can find that is not
  *    already opened for indexes 0..idx-1, searching up to 16 device nodes
@@ -526,12 +525,19 @@ static bool __get_card_for_nth_filter(int idx, struct igt_device_card *card)
  */
 int __drm_open_driver_another(int idx, int chipset)
 {
+	int filter_count = igt_device_filter_count();
 	int fd = -1;
 
-	if (chipset != DRIVER_VGEM && igt_device_filter_count() > idx) {
+	if (chipset != DRIVER_VGEM && filter_count) {
 		struct igt_device_card card;
 		bool found;
 
+		if (idx < 0 || idx >= filter_count) {
+			igt_debug("Cannot open, index out of bounds: %d, filter_count=%d\n",
+				 idx, filter_count);
+			return -1;
+		}
+
 		found = __get_card_for_nth_filter(idx, &card);
 
 		if (!found) {
@@ -542,19 +548,17 @@ int __drm_open_driver_another(int idx, int chipset)
 		if (!found || !strlen(card.card))
 			igt_warn("No card matches the filter! [%s]\n",
 				 igt_device_filter_get(idx));
-		else if (_is_already_opened(card.card, idx))
-			igt_warn("card maching filter %d is already opened\n", idx);
 		else
 			fd = __open_driver_exact(card.card, chipset);
 
 	} else {
 		/* no filter for device idx, let's open whatever is available */
 		fd = __open_driver("/dev/dri/card", 0, chipset, idx);
+		if (fd >= 0)
+			_set_opened_fd(idx, fd);
 	}
 
 	if (fd >= 0) {
-		_set_opened_fd(idx, fd);
-
 		/* Cache xe_device struct. */
 		if (is_xe_device(fd))
 			xe_device_get(fd);
-- 
2.42.0