drm/amdgpu: fix off by one in amdgpu_gfx_kiq_acquire()

BugLink: https://bugs.launchpad.net/bugs/1971497
[ Upstream commit 1647b54ed55d4d48c7199d439f8834626576cbe9 ]

This post-op should be a pre-op so that we do not pass -1 as the bit
number to test_bit().  The current code will loop downwards from 63 to
-1.  After changing to a pre-op, it loops from 63 to 0.

Fixes: 71c37505e7ea ("drm/amdgpu/gfx: move more common KIQ code to amdgpu_gfx.c")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
index f9bef3154b99833eff9a5f595c39a9a269176a79..2659202f2026b2f98eb4023c52183b30dd55fcd7 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
@@ -263,7 +263,7 @@ static int amdgpu_gfx_kiq_acquire(struct amdgpu_device *adev,
                    * adev->gfx.mec.num_pipe_per_mec
                    * adev->gfx.mec.num_queue_per_pipe;
 
-       while (queue_bit-- >= 0) {
+       while (--queue_bit >= 0) {
                if (test_bit(queue_bit, adev->gfx.mec.queue_bitmap))
                        continue;