[PATCH i-g-t] tools/gputop: Fix engine columns with amdgpu

[Tvrtko Ursulin <tursulin@igalia.com>]

From: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>

Amdgpu kernel driver skips output of fdinfo keys for unused engines. That
is completely legal but corrupts the column formatting in the current
code.

Fix it by simply treating change in detected engines used by a client
as trigger to re-emit a new header. This ensures columns are always
correctly aligned, albeit with a cost of potentially duplicating the
header for the same DRM minor.

This is considered good enough for a reference implementation. The
alternative would be to add some real per DRM minor state tracking which
sounds like an overkill, at least until gputop gains a nicer (any) UI.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
---
 tools/gputop.c | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/tools/gputop.c b/tools/gputop.c
index 71e28f43ee4c..76075c5dde8b 100644
--- a/tools/gputop.c
+++ b/tools/gputop.c
@@ -119,11 +119,36 @@ print_client_header(struct igt_drm_client *c, int lines, int con_w, int con_h,
 	return lines;
 }
 
+static bool
+engines_identical(const struct igt_drm_client *c,
+		  const struct igt_drm_client *pc)
+{
+	unsigned int i;
+
+	if (c->engines->num_engines != pc->engines->num_engines ||
+	    c->engines->max_engine_id != pc->engines->max_engine_id)
+		return false;
+
+	for (i = 0; i <= c->engines->max_engine_id; i++)
+		if (c->engines->capacity[i] != pc->engines->capacity[i] ||
+		    !!c->engines->names[i] != !!pc->engines->names[i] ||
+		    strcmp(c->engines->names[i], pc->engines->names[i]))
+			return false;
+
+	return true;
+}
 
 static bool
 newheader(const struct igt_drm_client *c, const struct igt_drm_client *pc)
 {
-	return !pc || c->drm_minor != pc->drm_minor;
+	return !pc || c->drm_minor != pc->drm_minor ||
+	       /*
+		* Below is a a hack for drivers like amdgpu which omit listing
+		* unused engines. Simply treat them as separate minors which
+		* will ensure the per-engine columns are correctly sized in all
+		* cases.
+		*/
+	       !engines_identical(c, pc);
 }
 
 static int
-- 
2.44.0