Am 02.11.2017 um 00:21 schrieb Felix Kuehling: > From: shaoyunl <Shaoyun.Liu at amd.com> > > ffs function return the position of the first bit set on 1 based. > (bit zero returns 1). > > Signed-off-by: shaoyun liu <shaoyun.liu at amd.com> > Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com> > --- > 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;
