Lukas Wunner e02328f47b vga_switcheroo: Drop client power state VGA_SWITCHEROO_INIT ... hda_intel.c:azx_probe() defers initialization of an audio controller on the discrete GPU if the GPU is powered off. The power state of the GPU is determined by calling vga_switcheroo_get_client_state(). vga_switcheroo_get_client_state() returns VGA_SWITCHEROO_INIT if vga_switcheroo is not enabled, i.e. if no second GPU or no handler has registered. This can go wrong in the following scenario: - Driver for the integrated GPU is not loaded. - Driver for the discrete GPU registers with vga_switcheroo, uses driver power control to power down the GPU, handler cuts power to the GPU. - Driver for the audio controller gets loaded after the GPU was powered down, calls vga_switcheroo_get_client_state() which returns VGA_SWITCHEROO_INIT instead of VGA_SWITCHEROO_OFF. - Consequence: azx_probe() tries to initialize the audio controller even though the GPU is powered down. The power state VGA_SWITCHEROO_INIT was introduced by c8e9cf7bb2 ("vga_switcheroo: Add a helper function to get the client state"). It is not apparent what its benefit might be. The idea seems to be to initialize the audio controller even if the power state is VGA_SWITCHEROO_OFF (were vga_switcheroo enabled), but as shown above this can fail. Drop VGA_SWITCHEROO_INIT to solve this. Acked-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Dave Airlie <airlied@redhat.com>		2015-11-05 11:07:36 +10:00
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Kconfig
Makefile
vga_switcheroo.c	vga_switcheroo: Drop client power state VGA_SWITCHEROO_INIT	2015-11-05 11:07:36 +10:00
vgaarb.c	vgaarb: use kzalloc in vga_arbiter_add_pci_device()	2015-10-01 11:25:23 +02:00