Am 02.11.2017 um 00:21 schrieb Felix Kuehling:
From: shaoyunl <[email protected]>
ffs function return the position of the first bit set on 1 based.
(bit zero returns 1).
Signed-off-by: shaoyun liu <[email protected]>
Signed-off-by: Felix Kuehling <[email protected]>
---
drivers/gpu/drm/amd/amdkfd/kfd_mqd_manager_cik.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
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 4859d26..4728fad 100644
--- 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 |
Usually we use order_base_2 for this. See cik_sdma.c for example:
rb_bufsz = order_base_2(ring->ring_size / 4);
Additional to that I won't expect that sizeof(unsigned int) is ever
something else than 4 on any CPU that Linux supports, but that we need
to divide the value by 4 is a programming detail of our hardware and not
something dependent on the CPU/Compiler in use.
So I think using 4 over sizeof(unsigned int) is cleaner and easier to
understand.
Regards,
Christian.
1 << SDMA0_RLC0_RB_CNTL__RPTR_WRITEBACK_ENABLE__SHIFT |
6 << SDMA0_RLC0_RB_CNTL__RPTR_WRITEBACK_TIMER__SHIFT;
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