[igt-dev] [PATCH i-g-t] lib/kms: warn if we commit without outputs

[Daniel Vetter]

With the high-level helpers requiring outputs there's not point
in silently ignoring issues anymore. Complain about that if it
ever happens.

This reverts

commit 212b71372bfbb73663d872df31118d6b396ada4f
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Fri Sep 14 21:03:38 2018 +0100

    lib/kms: Skip no-op display updates

which created an in my opinion serious API issue by silently dropping
possible errors on the floor. Instead of silently second guess what
the test might have wanted to do in the absence of display outputs
it's much better to be explicit, and enforce that.

v2: Improve commit message.

v3: Switch to an assert and update comments, to make it clear this is
igt_display api abuse (Arek).

Cc: Antonio Argenziano <antonio.argenziano at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Arkadiusz Hiler <arkadiusz.hiler at intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com> (v2)
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 lib/igt_kms.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index 7214101e2696..73cea75d19f0 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -3292,8 +3292,8 @@ static int do_display_commit(igt_display_t *display,
 	enum pipe pipe;
 	LOG_INDENT(display, "commit");
 
-	if (!display->n_pipes || !display->n_outputs)
-		return 0; /* nothing to do */
+	/* someone managed to bypass igt_display_require, catch them */
+	assert(display->n_pipes && display->n_outputs);
 
 	igt_display_refresh(display);
 
@@ -3345,8 +3345,8 @@ int igt_display_try_commit_atomic(igt_display_t *display, uint32_t flags, void *
 {
 	int ret;
 
-	if (!display->n_pipes || !display->n_outputs)
-		return 0; /* nothing to do */
+	/* someone managed to bypass igt_display_require, catch them */
+	assert(display->n_pipes && display->n_outputs);
 
 	LOG_INDENT(display, "commit");
 
-- 
2.19.1