leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

drm/amdgpu: request reg_val_offs each kiq read reg

Browse Source 
According to the current kiq read register method,
there will be race condition when using KIQ to read
register if multiple clients want to read at same time
just like the expample below:
1. client-A start to read REG-0 throguh KIQ
2. client-A poll the seqno-0
3. client-B start to read REG-1 through KIQ
4. client-B poll the seqno-1
5. the kiq complete these two read operation
6. client-A to read the register at the wb buffer and
   get REG-1 value

Therefore, use amdgpu_device_wb_get() to request reg_val_offs
for each kiq read register.

v2: fix the error remove
v3: fix the print typo
v4: remove unused variables

Signed-off-by: Yintian Tao <yttao@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Yintian Tao
2020-04-22 19:58:22 +08:00
committed by Alex Deucher
parent e09d40bdba
commit 5420819401
7 changed files with 41 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
View File

@@ -304,10 +304,6 @@ int amdgpu_gfx_kiq_init_ring(struct amdgpu_device *adev,
spin_lock_init(&kiq->ring_lock);
r = amdgpu_device_wb_get(adev, &kiq->reg_val_offs);
if (r)
return r;
ring->adev = NULL;
ring->ring_obj = NULL;
ring->use_doorbell = true;
@@ -331,7 +327,6 @@ int amdgpu_gfx_kiq_init_ring(struct amdgpu_device *adev,
void amdgpu_gfx_kiq_free_ring(struct amdgpu_ring *ring)
{
amdgpu_device_wb_free(ring->adev, ring->adev->gfx.kiq.reg_val_offs);
amdgpu_ring_fini(ring);
}
@@ -672,15 +667,20 @@ uint32_t amdgpu_kiq_rreg(struct amdgpu_device *adev, uint32_t reg)
{
signed long r, cnt = 0;
unsigned long flags;
uint32_t seq;
uint32_t seq, reg_val_offs = 0, value = 0;
struct amdgpu_kiq *kiq = &adev->gfx.kiq;
struct amdgpu_ring *ring = &kiq->ring;
BUG_ON(!ring->funcs->emit_rreg);
spin_lock_irqsave(&kiq->ring_lock, flags);
if (amdgpu_device_wb_get(adev, &reg_val_offs)) {
spin_unlock_irqrestore(&kiq->ring_lock, flags);
pr_err("critical bug! too many kiq readers\n");
goto failed_kiq_read;
}
amdgpu_ring_alloc(ring, 32);
amdgpu_ring_emit_rreg(ring, reg);
amdgpu_ring_emit_rreg(ring, reg, reg_val_offs);
amdgpu_fence_emit_polling(ring, &seq);
amdgpu_ring_commit(ring);
spin_unlock_irqrestore(&kiq->ring_lock, flags);
@@ -707,7 +707,10 @@ uint32_t amdgpu_kiq_rreg(struct amdgpu_device *adev, uint32_t reg)
if (cnt > MAX_KIQ_REG_TRY)
goto failed_kiq_read;
return adev->wb.wb[kiq->reg_val_offs];
mb();
value = adev->wb.wb[reg_val_offs];
amdgpu_device_wb_free(adev, reg_val_offs);
return value;
failed_kiq_read:
pr_err("failed to read reg:%x\n", reg);