[PATCH net-next v2 1/2] net: ethernet: mtk_eth_soc: skip page_pool

[Sandeep Haemoon]

On NETSYS v2 and later every RX ring gets a page_pool.  The pool is
created with order-0 pages and MTK_PP_MAX_BUF_SIZE (PAGE_SIZE minus the
headroom), so it can only serve rings whose buffers fit in one page.
The HW-LRO ring already needs 12K buffers, and 9K jumbo adds more such
rings; for those the descriptor length is larger than a page, so the
pool cannot back them.

Only create the pool when ring->frag_size fits in a page.  The other
rings fall back to the netdev_alloc_frag()/mtk_max_lro_buf_alloc() path
that is already there.

Link: https://github.com/mediatek/mtk-openwrt-feeds
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
Signed-off-by: Sandeep Haemoon <sandeeph@xxxxxxxxxxx>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index ad0fdc413..29370376f 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -2819,7 +2819,12 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
 	if (!ring->data)
 		return -ENOMEM;
 
-	if (mtk_page_pool_enabled(eth)) {
+	/* page_pool hands out order-0 pages and the pool is created with
+	 * MTK_PP_MAX_BUF_SIZE, so only rings whose buffers fit in a page can
+	 * use it.  The larger rings (HW-LRO, and 9K jumbo once enabled) take
+	 * the netdev_alloc_frag()/mtk_max_lro_buf_alloc() path below.
+	 */
+	if (mtk_page_pool_enabled(eth) && ring->frag_size <= PAGE_SIZE) {
 		struct page_pool *pp;
 
 		pp = mtk_create_page_pool(eth, &ring->xdp_q, ring_no,
-- 
2.53.0