Lenovo Thinkpad T440s suffers from constant background noises, and it
seems to be a generic hardware issue on this model:
https://forums.lenovo.com/t5/ThinkPad-T400-T500-and-newer-T/T440s-speaker-noise/td-p/1339883
As the noise comes from the analog loopback path, disabling the path
is the easy workaround.
Also, the machine gives significant cracking noises at PM suspend. A
workaround found by trial-and-error is to disable the shutup callback
currently used for ALC269-variant.
This patch addresses these noise issues by introducing a new fixup
chain. Although the same workaround might be applicable to other
Thinkpad models, it's applied only to T440s (17aa:220c) in this patch,
so far, just to be safe (you chicken!). As a compromise, a new model
option string "tp440" is provided now, though, so that owners of other
Thinkpad models can test it more easily.
Bugzilla: https://bugzilla.opensuse.org/show_bug.cgi?id=958504
Reported-and-tested-by: Tim Hardeck <thardeck@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
9a81123048