[PATCH] drm/atomic: Convert a warning to dbg atomic printk

[Zack Rusin]

From: Zack Rusin <zackr at vmware.com>

By default each flip times out after 0.1 sec and a warning about the
time out is added to the kernel log. The warning is harmless because
there's another flip coming right after but it can quickly fill up
the log, e.g. missing 2 flips every second over a 24 hour span will
add about 172 thousand lines to the log.
Skip printing it by default and instead add it to the atomic drm debug
category. It can be trivially enabled via drm.debug=0x10 and it avoids
filling up logs by default.

This is particularly important on vm's where presentation might be CPU
bound and running multiple vm's or under a CPU heavy load can easily
lead to missing mutliple flips and any actual errors are often blamed
on this due to it being so prevalent in the logs.
Fixes a bunch of bugs reported to RedHat (1792515, 1884401, 1896139
and 1884401) and SUSE (210123) where people complain about having
their logs spammed by this message and blame various errors on it.

Signed-off-by: Zack Rusin <zackr at vmware.com>
---
 drivers/gpu/drm/drm_atomic_helper.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 9603193d2fa1..e88b4d83fd5c 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1566,8 +1566,8 @@ void drm_atomic_helper_wait_for_flip_done(struct drm_device *dev,
 
 		ret = wait_for_completion_timeout(&commit->flip_done, 10 * HZ);
 		if (ret == 0)
-			drm_err(dev, "[CRTC:%d:%s] flip_done timed out\n",
-				crtc->base.id, crtc->name);
+			drm_dbg_atomic(dev, "[CRTC:%d:%s] flip_done timed out\n",
+				       crtc->base.id, crtc->name);
 	}
 
 	if (old_state->fake_commit)
-- 
2.32.0