Hi all,
commit 92c177b7947d9c889ea7b024871445015ea74221
Author: Lyude
Date: Wed Feb 22 16:34:53 2017 -0500
drm/radeon/dp_auxch: Ratelimit aux transfer debug messages
does more harm than good in my opinion. Since this commit, I see
several occurrences of the following message in my kernel log daily:
radeon_dp_aux_transfer_native: 74 callbacks suppressed
I never got to see the "callback" in question though, not even once, as
this is a debug message which is off by default. Before the change, I
would not get any such message in the kernel log (as I would expect
when everything works as intended.)
Does this debug message really have any practical value? If not, the
easiest solution would be to simply drop it:
--- a/drivers/gpu/drm/radeon/radeon_dp_auxch.c
+++ b/drivers/gpu/drm/radeon/radeon_dp_auxch.c
@@ -168,8 +168,10 @@ radeon_dp_aux_transfer_native(struct drm
goto done;
}
if (tmp & AUX_RX_ERROR_FLAGS) {
- DRM_DEBUG_KMS_RATELIMITED("dp_aux_ch flags not zero: %08x\n",
- tmp);
+ /*
+ * aux transfers always fail with non-zero status flags when
+ * there's nothing connected on the port
+ */
ret = -EIO;
goto done;
}
I can resend this as a formal patch if you agree with this solution.
The actual cause of the problem is that ___ratelimit() prints its
message at KERN_WARNING level regardless of the level of the message
being suppressed. This makes ratelimiting debug, info or notice
messages awkward. Looks like a design overlook to me, maybe it should
be fixed, but that's a much bigger and intrusive change than the
proposal above.
--
Jean Delvare
SUSE L3 Support
