[Intel-gfx] [RFC PATCH i-g-t] lib/i915/perf: Fix non-card0 processing

[Janusz Krzysztofik]

IGT i915/perf library functions now always operate on sysfs perf
attributes of card0 device node, no matter which DRM device fd a user
passes.  The intention was to always switch to primary device node if
a user passes a render device node fd, but that breaks handling of
non-card0 devices.

Instead of forcibly using DRM device minor number 0 when opening a
device sysfs area, convert device minor number of a user passed device
fd to the minor number of respective primary (cardX) device node.

Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>
---
 lib/i915/perf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/i915/perf.c b/lib/i915/perf.c
index 56d5c0b3a..336824df7 100644
--- a/lib/i915/perf.c
+++ b/lib/i915/perf.c
@@ -376,8 +376,8 @@ open_master_sysfs_dir(int drm_fd)
 	if (fstat(drm_fd, &st) || !S_ISCHR(st.st_mode))
                 return -1;
 
-        snprintf(path, sizeof(path), "/sys/dev/char/%d:0",
-                 major(st.st_rdev));
+        snprintf(path, sizeof(path), "/sys/dev/char/%d:%d",
+                 major(st.st_rdev), minor(st.st_rdev) & ~128);
 
 	return open(path, O_DIRECTORY);
 }
-- 
2.25.1