path: root/drivers/gpu/vga
diff options
authorLukas Wunner <>2015-09-08 14:17:47 +0200
committerDave Airlie <>2015-11-05 11:07:36 +1000
commite02328f47bd75fde9decf9657ec7d769b370f857 (patch)
tree42a0829fb93bb05559b140211fdcc2d2b20cd40c /drivers/gpu/vga
parentb26eae934e94240de6bcbcd77b4bdec8bc005168 (diff)
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 c8e9cf7bb240 ("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 <> Signed-off-by: Lukas Wunner <> Signed-off-by: Dave Airlie <>
Diffstat (limited to 'drivers/gpu/vga')
1 files changed, 0 insertions, 2 deletions
diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
index 56bbbd65ae8a..41edd5a3f100 100644
--- a/drivers/gpu/vga/vga_switcheroo.c
+++ b/drivers/gpu/vga/vga_switcheroo.c
@@ -356,8 +356,6 @@ enum vga_switcheroo_state vga_switcheroo_get_client_state(struct pci_dev *pdev)
client = find_client_from_pci(&vgasr_priv.clients, pdev);
if (!client)
- else if (!
ret = client->pwr_state;