drm/amdkfd: Fix SDMA ring buffer size calculation

ffs function return the position of the first bit set on 1 based.
(bit zero returns 1).

Signed-off-by: shaoyun liu <shaoyun.liu@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_cik.c b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_cik.c
index 4859d263fa2a3ce51a816b2f3b36b98f298cf9f7..4728fad3fd7425ca2e0ef2fbb805dc145d078df7 100644 (file)
--- a/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_cik.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_cik.c
@@ -202,8 +202,8 @@ static int update_mqd_sdma(struct mqd_manager *mm, void *mqd,
        struct cik_sdma_rlc_registers *m;
 
        m = get_sdma_mqd(mqd);
-       m->sdma_rlc_rb_cntl = ffs(q->queue_size / sizeof(unsigned int)) <<
-                       SDMA0_RLC0_RB_CNTL__RB_SIZE__SHIFT |
+       m->sdma_rlc_rb_cntl = (ffs(q->queue_size / sizeof(unsigned int)) - 1)
+                       << SDMA0_RLC0_RB_CNTL__RB_SIZE__SHIFT |
                        q->vmid << SDMA0_RLC0_RB_CNTL__RB_VMID__SHIFT |
                        1 << SDMA0_RLC0_RB_CNTL__RPTR_WRITEBACK_ENABLE__SHIFT |
                        6 << SDMA0_RLC0_RB_CNTL__RPTR_WRITEBACK_TIMER__SHIFT;