cxgb4/cxgb4vf: For T5 use Packing and Padding Boundaries for SGE DMA transfers

T5 introduces the ability to have separate Packing and Padding Boundaries
for SGE DMA transfers from the chip to Host Memory. This change set takes
advantage of that to set up a smaller Padding Boundary to conserve PCI Link
and Memory Bandwidth with T5.

Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/net/ethernet/chelsio/cxgb4vf/t4vf_hw.c b/drivers/net/ethernet/chelsio/cxgb4vf/t4vf_hw.c
index e984fdc48ba2..dc30d2852850 100644
--- a/drivers/net/ethernet/chelsio/cxgb4vf/t4vf_hw.c
+++ b/drivers/net/ethernet/chelsio/cxgb4vf/t4vf_hw.c
@@ -468,6 +468,29 @@ int t4vf_get_sge_params(struct adapter *adapter)
 	sge_params->sge_timer_value_2_and_3 = vals[5];
 	sge_params->sge_timer_value_4_and_5 = vals[6];
 
+	/* T4 uses a single control field to specify both the PCIe Padding and
+	 * Packing Boundary.  T5 introduced the ability to specify these
+	 * separately with the Padding Boundary in SGE_CONTROL and and Packing
+	 * Boundary in SGE_CONTROL2.  So for T5 and later we need to grab
+	 * SGE_CONTROL in order to determine how ingress packet data will be
+	 * laid out in Packed Buffer Mode.  Unfortunately, older versions of
+	 * the firmware won't let us retrieve SGE_CONTROL2 so if we get a
+	 * failure grabbing it we throw an error since we can't figure out the
+	 * right value.
+	 */
+	if (!is_t4(adapter->params.chip)) {
+		params[0] = (FW_PARAMS_MNEM(FW_PARAMS_MNEM_REG) |
+			     FW_PARAMS_PARAM_XYZ(SGE_CONTROL2_A));
+		v = t4vf_query_params(adapter, 1, params, vals);
+		if (v != FW_SUCCESS) {
+			dev_err(adapter->pdev_dev,
+				"Unable to get SGE Control2; "
+				"probably old firmware.\n");
+			return v;
+		}
+		sge_params->sge_control2 = vals[0];
+	}
+
 	params[0] = (FW_PARAMS_MNEM(FW_PARAMS_MNEM_REG) |
 		     FW_PARAMS_PARAM_XYZ(SGE_INGRESS_RX_THRESHOLD));
 	v = t4vf_query_params(adapter, 1, params, vals);