[PATCH net-next] cxgb4vf: Fix SGE FL buffer initialization logic for 64K pages

[Ganesh Goudar <ganeshgr@chelsio.com>]

From: Arjun Vynipadath <arjun@chelsio.com>

We'd come in with SGE_FL_BUFFER_SIZE[0] and [1] both equal to 64KB and
the extant logic would flag that as an error. This was already fixed in
cxgb4 driver with "92ddcc7 cxgb4: Fix some small bugs in
t4_sge_init_soft() when our Page Size is 64KB".

Original Work by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: Arjun Vynipadath <arjun@chelsio.com>
Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
---
 drivers/net/ethernet/chelsio/cxgb4vf/sge.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb4vf/sge.c b/drivers/net/ethernet/chelsio/cxgb4vf/sge.c
index 14d7e67..129b914 100644
--- a/drivers/net/ethernet/chelsio/cxgb4vf/sge.c
+++ b/drivers/net/ethernet/chelsio/cxgb4vf/sge.c
@@ -2619,8 +2619,8 @@ void t4vf_sge_stop(struct adapter *adapter)
 int t4vf_sge_init(struct adapter *adapter)
 {
 	struct sge_params *sge_params = &adapter->params.sge;
-	u32 fl0 = sge_params->sge_fl_buffer_size[0];
-	u32 fl1 = sge_params->sge_fl_buffer_size[1];
+	u32 fl_small_pg = sge_params->sge_fl_buffer_size[0];
+	u32 fl_large_pg = sge_params->sge_fl_buffer_size[1];
 	struct sge *s = &adapter->sge;
 
 	/*
@@ -2628,9 +2628,20 @@ int t4vf_sge_init(struct adapter *adapter)
 	 * the Physical Function Driver.  Ideally we should be able to deal
 	 * with _any_ configuration.  Practice is different ...
 	 */
-	if (fl0 != PAGE_SIZE || (fl1 != 0 && fl1 <= fl0)) {
+
+	/* We only bother using the Large Page logic if the Large Page Buffer
+	 * is larger than our Page Size Buffer.
+	 */
+	if (fl_large_pg <= fl_small_pg)
+		fl_large_pg = 0;
+
+	/* The Page Size Buffer must be exactly equal to our Page Size and the
+	 * Large Page Size Buffer should be 0 (per above) or a power of 2.
+	 */
+	if (fl_small_pg != PAGE_SIZE ||
+	    (fl_large_pg & (fl_large_pg - 1)) != 0) {
 		dev_err(adapter->pdev_dev, "bad SGE FL buffer sizes [%d, %d]\n",
-			fl0, fl1);
+			fl_small_pg, fl_large_pg);
 		return -EINVAL;
 	}
 	if ((sge_params->sge_control & RXPKTCPLMODE_F) !=
@@ -2642,8 +2653,8 @@ int t4vf_sge_init(struct adapter *adapter)
 	/*
 	 * Now translate the adapter parameters into our internal forms.
 	 */
-	if (fl1)
-		s->fl_pg_order = ilog2(fl1) - PAGE_SHIFT;
+	if (fl_large_pg)
+		s->fl_pg_order = ilog2(fl_large_pg) - PAGE_SHIFT;
 	s->stat_len = ((sge_params->sge_control & EGRSTATUSPAGESIZE_F)
 			? 128 : 64);
 	s->pktshift = PKTSHIFT_G(sge_params->sge_control);
-- 
2.1.0