From: Takashi Iwai <tiwai@suse.de>
Date: Thu, 26 Apr 2012 10:13:25 +0000 (+0200)
Subject: ALSA: hda - Check the dead HDMI audio controller by vga-switcheroo
X-Git-Tag: v3.5-rc1~83^2~3
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9121947d696df7ea259c0102e449da9621b9cf92;p=pandora-kernel.git

ALSA: hda - Check the dead HDMI audio controller by vga-switcheroo

When a discrete-GPU is disabled by the VGA switcheroo, the
corresponding HD-audio controller for HDMI output is also disabled.
Such a dead controller still appears in the PCI device list, but you
can't access properly any longer (even calling pci_read_config_*()
triggers Oops!) which leads the stall of the whole communication of
the driver.

This patch adds a check of graphics controller at the probe time to
see whether it's disabled by vga-switcheroo.  If disabled, skip the
whole initialization of this controller.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=43155

Signed-off-by: Takashi Iwai <tiwai@suse.de>
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