ALSA: hda - Fix noise problems on Thinkpad T440s
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=958504Reported-and-tested-by: Tim Hardeck <thardeck@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
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