RDMA/cxgb4: Max fastreg depth depends on DSGL support

The max depth of a fastreg mr depends on whether the device supports
DSGL or not.  So compute it dynamically based on the device support
and the module use_dsgl option.
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/cxgb4/provider.c

@@ -328,7 +328,7 @@ static int c4iw_query_device(struct ib_device *ibdev,
 	props->max_mr = c4iw_num_stags(&dev->rdev);
 	props->max_pd = T4_MAX_NUM_PD;
 	props->local_ca_ack_delay = 0;
-	props->max_fast_reg_page_list_len = T4_MAX_FR_DEPTH;
+	props->max_fast_reg_page_list_len = t4_max_fr_depth(use_dsgl);
 
 	return 0;
 }

drivers/infiniband/hw/cxgb4/qp.c

@@ -566,7 +566,8 @@ static int build_fastreg(struct t4_sq *sq, union t4_wr *wqe,
 	int pbllen = roundup(wr->wr.fast_reg.page_list_len * sizeof(u64), 32);
 	int rem;
 
-	if (wr->wr.fast_reg.page_list_len > T4_MAX_FR_DEPTH)
+	if (wr->wr.fast_reg.page_list_len >
+	    t4_max_fr_depth(use_dsgl))
 		return -EINVAL;
 
 	wqe->fr.qpbinde_to_dcacpu = 0;

drivers/infiniband/hw/cxgb4/t4.h

@@ -84,7 +84,14 @@ struct t4_status_page {
 			sizeof(struct fw_ri_isgl)) / sizeof(struct fw_ri_sge))
 #define T4_MAX_FR_IMMD ((T4_SQ_NUM_BYTES - sizeof(struct fw_ri_fr_nsmr_wr) - \
 			sizeof(struct fw_ri_immd)) & ~31UL)
-#define T4_MAX_FR_DEPTH (1024 / sizeof(u64))
+#define T4_MAX_FR_IMMD_DEPTH (T4_MAX_FR_IMMD / sizeof(u64))
+#define T4_MAX_FR_DSGL 1024
+#define T4_MAX_FR_DSGL_DEPTH (T4_MAX_FR_DSGL / sizeof(u64))
+
+static inline int t4_max_fr_depth(int use_dsgl)
+{
+	return use_dsgl ? T4_MAX_FR_DSGL_DEPTH : T4_MAX_FR_IMMD_DEPTH;
+}
 
 #define T4_RQ_NUM_SLOTS 2
 #define T4_RQ_NUM_BYTES (T4_EQ_ENTRY_SIZE * T4_RQ_NUM_SLOTS)