On Thu, Mar 19, 2020 at 07:42:04PM +0800, Pan, Xinhui wrote: > > > > 2020年3月19日 18:51，Huang Rui <ray.huang@xxxxxxx> 写道： > > > > The queue buffer index starts from position 0, so the available buffer size > > which starts from position 0 to rptr should be "rptr" index value. While the > > packet_size_in_dwords == rptr, the available buffer is just good enough. > > > > Signed-off-by: Huang Rui <ray.huang@xxxxxxx> > > --- > > drivers/gpu/drm/amd/amdkfd/kfd_kernel_queue.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_kernel_queue.c b/drivers/gpu/drm/amd/amdkfd/kfd_kernel_queue.c > > index bae7064..4667c8f 100644 > > --- a/drivers/gpu/drm/amd/amdkfd/kfd_kernel_queue.c > > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_kernel_queue.c > > @@ -263,7 +263,7 @@ int kq_acquire_packet_buffer(struct kernel_queue *kq, > > /* make sure after rolling back to position 0, there is > > * still enough space. > > */ > > - if (packet_size_in_dwords >= rptr) > > + if (packet_size_in_dwords > rptr) > > rptr should always be > wptr unless ring is empty. > > say, rptr is 4, packet_size_in_dwords is 4. Then wptr changes from 0 to 4, that is illegal. > Hey, xinhui, yes. :-) See the comment "we can only use up to queue_size_dword - 1 dwords", that we cannot use the whole packet slots in the queue, it's to differentiate empty and full cases. Thanks, Ray > > > goto err_no_space; > > > > /* fill nops, roll back and start at position 0 */ > > -- > > 2.7.4 > > > > _______________________________________________ > > amd-gfx mailing list > > amd-gfx@xxxxxxxxxxxxxxxxxxxxx > > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.freedesktop.org%2Fmailman%2Flistinfo%2Famd-gfx&data=02%7C01%7Cxinhui.pan%40amd.com%7Cdb98cfd84b764e77d20e08d7cbf38dff%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637202119950119907&sdata=mqrl2uooQ95Dns4l6CtmmOBCm%2FqZyw1pX48VA20mlZY%3D&reserved=0 > _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
