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, 29 insertions, 2 deletions

diff --git a/drivers/net/ethernet/chelsio/cxgb4vf/sge.c b/drivers/net/ethernet/chelsio/cxgb4vf/sge.c
index a18830d8aa6d..cd5b7896cb67 100644
--- a/drivers/net/ethernet/chelsio/cxgb4vf/sge.c
+++ b/drivers/net/ethernet/chelsio/cxgb4vf/sge.c
@@ -2436,6 +2436,7 @@ int t4vf_sge_init(struct adapter *adapter)
 	u32 fl0 = sge_params->sge_fl_buffer_size[0];
 	u32 fl1 = sge_params->sge_fl_buffer_size[1];
 	struct sge *s = &adapter->sge;
+	unsigned int ingpadboundary, ingpackboundary;
 
 	/*
 	 * Start by vetting the basic SGE parameters which have been set up by
@@ -2460,8 +2461,34 @@ int t4vf_sge_init(struct adapter *adapter)
 	s->stat_len = ((sge_params->sge_control & EGRSTATUSPAGESIZE_MASK)
 			? 128 : 64);
 	s->pktshift = PKTSHIFT_GET(sge_params->sge_control);
-	s->fl_align = 1 << (INGPADBOUNDARY_GET(sge_params->sge_control) +
-			    SGE_INGPADBOUNDARY_SHIFT);
+
+	/* T4 uses a single control field to specify both the PCIe Padding and
+	 * Packing Boundary.  T5 introduced the ability to specify these
+	 * separately.  The actual Ingress Packet Data alignment boundary
+	 * within Packed Buffer Mode is the maximum of these two
+	 * specifications.  (Note that it makes no real practical sense to
+	 * have the Pading Boudary be larger than the Packing Boundary but you
+	 * could set the chip up that way and, in fact, legacy T4 code would
+	 * end doing this because it would initialize the Padding Boundary and
+	 * leave the Packing Boundary initialized to 0 (16 bytes).)
+	 */
+	ingpadboundary = 1 << (INGPADBOUNDARY_GET(sge_params->sge_control) +
+			       X_INGPADBOUNDARY_SHIFT);
+	if (is_t4(adapter->params.chip)) {
+		s->fl_align = ingpadboundary;
+	} else {
+		/* T5 has a different interpretation of one of the PCIe Packing
+		 * Boundary values.
+		 */
+		ingpackboundary = INGPACKBOUNDARY_G(sge_params->sge_control2);
+		if (ingpackboundary == INGPACKBOUNDARY_16B_X)
+			ingpackboundary = 16;
+		else
+			ingpackboundary = 1 << (ingpackboundary +
+						INGPACKBOUNDARY_SHIFT_X);
+
+		s->fl_align = max(ingpadboundary, ingpackboundary);
+	}
 
 	/*
 	 * Set up tasklet timers.