[PATCH net 4/4] bnxt_en: Fix _bnxt_get_max_rings() for 57500 chips.

[Michael Chan <michael.chan@broadcom.com>]

The CP rings are accounted differently on the new 57500 chips.  There
must be enough CP rings for the sum of RX and TX rings on the new
chips.  The current logic may be over-estimating the RX and TX rings.

The output parameter max_cp should be the maximum NQs capped by
MSIX vectors available for networking in the context of 57500 chips.
The existing code which uses CMPL rings capped by the MSIX vectors
works most of the time but is not always correct.

Signed-off-by: Michael Chan <michael.chan@broadcom.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 2e90d98..5d21c14 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -9827,13 +9827,16 @@ static void _bnxt_get_max_rings(struct bnxt *bp, int *max_rx, int *max_tx,
 				int *max_cp)
 {
 	struct bnxt_hw_resc *hw_resc = &bp->hw_resc;
-	int max_ring_grps = 0;
+	int max_ring_grps = 0, max_irq;
 
 	*max_tx = hw_resc->max_tx_rings;
 	*max_rx = hw_resc->max_rx_rings;
-	*max_cp = min_t(int, bnxt_get_max_func_cp_rings_for_en(bp),
-			hw_resc->max_irqs - bnxt_get_ulp_msix_num(bp));
-	*max_cp = min_t(int, *max_cp, hw_resc->max_stat_ctxs);
+	*max_cp = bnxt_get_max_func_cp_rings_for_en(bp);
+	max_irq = min_t(int, bnxt_get_max_func_irqs(bp) -
+			bnxt_get_ulp_msix_num(bp),
+			bnxt_get_max_func_stat_ctxs(bp));
+	if (!(bp->flags & BNXT_FLAG_CHIP_P5))
+		*max_cp = min_t(int, *max_cp, max_irq);
 	max_ring_grps = hw_resc->max_hw_ring_grps;
 	if (BNXT_CHIP_TYPE_NITRO_A0(bp) && BNXT_PF(bp)) {
 		*max_cp -= 1;
@@ -9841,6 +9844,11 @@ static void _bnxt_get_max_rings(struct bnxt *bp, int *max_rx, int *max_tx,
 	}
 	if (bp->flags & BNXT_FLAG_AGG_RINGS)
 		*max_rx >>= 1;
+	if (bp->flags & BNXT_FLAG_CHIP_P5) {
+		bnxt_trim_rings(bp, max_rx, max_tx, *max_cp, false);
+		/* On P5 chips, max_cp output param should be available NQs */
+		*max_cp = max_irq;
+	}
 	*max_rx = min_t(int, *max_rx, max_ring_grps);
 }
 
-- 
2.5.1