[PATCH v2] vga_switcheroo: Fix impossible judgment condition

[Su Hui]

'id' is enum type like unsigned int, so it will never be less than zero.
It's better to check VGA_SWITCHEROO_UNKNOWN_ID too.

Fixes: 4aaf448fa975 ("vga_switcheroo: set audio client id according to bound GPU id")
Signed-off-by: Su Hui <suhui at nfschina.com>
---
v2:
 - add check of VGA_SWITCHEROO_UNKNOWN_ID(Dan's suggestion). 

By the way, all functions of 'get_client_id' will never return error code
or VGA_SWITCHEROO_UNKNOWN_ID，should we remove this check or keep it for
future.

 drivers/gpu/vga/vga_switcheroo.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c
index 365e6ddbe90f..cf530094f929 100644
--- a/drivers/gpu/vga/vga_switcheroo.c
+++ b/drivers/gpu/vga/vga_switcheroo.c
@@ -375,7 +375,7 @@ int vga_switcheroo_register_audio_client(struct pci_dev *pdev,
 	mutex_lock(&vgasr_mutex);
 	if (vgasr_priv.active) {
 		id = vgasr_priv.handler->get_client_id(vga_dev);
-		if (id < 0) {
+		if ((int)id < 0 || id == VGA_SWITCHEROO_UNKNOWN_ID) {
 			mutex_unlock(&vgasr_mutex);
 			return -EINVAL;
 		}
-- 
2.30.2