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From: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
To: Felix Fietkau <nbd@nbd.name>, John Crispin <john@phrozen.org>,
	Sean Wang <sean.wang@mediatek.com>,
	Mark Lee <Mark-MC.Lee@mediatek.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org
Cc: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
Subject: [PATCH net-next 10/14] net: ethernet: mtk_eth_soc: cache HW pointer of last freed TX descriptor
Date: Wed, 21 Apr 2021 21:09:10 -0700	[thread overview]
Message-ID: <20210422040914.47788-11-ilya.lipnitskiy@gmail.com> (raw)
In-Reply-To: <20210422040914.47788-1-ilya.lipnitskiy@gmail.com>

From: Felix Fietkau <nbd@nbd.name>

The value is only updated by the CPU, so it is cheaper to access from the
ring data structure than from a hardware register.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 8 ++++----
 drivers/net/ethernet/mediatek/mtk_eth_soc.h | 2 ++
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index 043ab5446524..01ad10c76d53 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -1362,7 +1362,7 @@ static int mtk_poll_tx_qdma(struct mtk_eth *eth, int budget,
 	struct mtk_tx_buf *tx_buf;
 	u32 cpu, dma;
 
-	cpu = mtk_r32(eth, MTK_QTX_CRX_PTR);
+	cpu = ring->last_free_ptr;
 	dma = mtk_r32(eth, MTK_QTX_DRX_PTR);
 
 	desc = mtk_qdma_phys_to_virt(ring, cpu);
@@ -1396,6 +1396,7 @@ static int mtk_poll_tx_qdma(struct mtk_eth *eth, int budget,
 		cpu = next_cpu;
 	}
 
+	ring->last_free_ptr = cpu;
 	mtk_w32(eth, cpu, MTK_QTX_CRX_PTR);
 
 	return budget;
@@ -1596,6 +1597,7 @@ static int mtk_tx_alloc(struct mtk_eth *eth)
 	atomic_set(&ring->free_count, MTK_DMA_SIZE - 2);
 	ring->next_free = &ring->dma[0];
 	ring->last_free = &ring->dma[MTK_DMA_SIZE - 1];
+	ring->last_free_ptr = (u32)(ring->phys + ((MTK_DMA_SIZE - 1) * sz));
 	ring->thresh = MAX_SKB_FRAGS;
 
 	/* make sure that all changes to the dma ring are flushed before we
@@ -1609,9 +1611,7 @@ static int mtk_tx_alloc(struct mtk_eth *eth)
 		mtk_w32(eth,
 			ring->phys + ((MTK_DMA_SIZE - 1) * sz),
 			MTK_QTX_CRX_PTR);
-		mtk_w32(eth,
-			ring->phys + ((MTK_DMA_SIZE - 1) * sz),
-			MTK_QTX_DRX_PTR);
+		mtk_w32(eth, ring->last_free_ptr, MTK_QTX_DRX_PTR);
 		mtk_w32(eth, (QDMA_RES_THRES << 8) | QDMA_RES_THRES,
 			MTK_QTX_CFG(0));
 	} else {
diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.h b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
index a8d388b02558..214da569e869 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -642,6 +642,7 @@ struct mtk_tx_buf {
  * @phys:		The physical addr of tx_buf
  * @next_free:		Pointer to the next free descriptor
  * @last_free:		Pointer to the last free descriptor
+ * @last_free_ptr:	Hardware pointer value of the last free descriptor
  * @thresh:		The threshold of minimum amount of free descriptors
  * @free_count:		QDMA uses a linked list. Track how many free descriptors
  *			are present
@@ -652,6 +653,7 @@ struct mtk_tx_ring {
 	dma_addr_t phys;
 	struct mtk_tx_dma *next_free;
 	struct mtk_tx_dma *last_free;
+	u32 last_free_ptr;
 	u16 thresh;
 	atomic_t free_count;
 	int dma_size;
-- 
2.31.1


  parent reply	other threads:[~2021-04-22  4:10 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-22  4:09 [PATCH net-next 00/14] mtk_eth_soc: fixes and performance improvements Ilya Lipnitskiy
2021-04-22  4:09 ` [PATCH net-next 01/14] net: ethernet: mtk_eth_soc: fix RX VLAN offload Ilya Lipnitskiy
2021-04-22  4:09 ` [PATCH net-next 02/14] net: ethernet: mtk_eth_soc: unmap RX data before calling build_skb Ilya Lipnitskiy
2021-04-22  4:09 ` [PATCH net-next 03/14] net: ethernet: mtk_eth_soc: fix build_skb cleanup Ilya Lipnitskiy
2021-04-22  4:09 ` [PATCH net-next 04/14] net: ethernet: mtk_eth_soc: use napi_consume_skb Ilya Lipnitskiy
2021-04-22  4:09 ` [PATCH net-next 05/14] net: ethernet: mtk_eth_soc: reduce MDIO bus access latency Ilya Lipnitskiy
2021-04-22 12:18   ` Andrew Lunn
2021-04-22 12:33   ` Felix Fietkau
2021-04-23  4:16     ` Ilya Lipnitskiy
2021-04-22  4:09 ` [PATCH net-next 06/14] net: ethernet: mtk_eth_soc: remove unnecessary TX queue stops Ilya Lipnitskiy
2021-04-22  4:09 ` [PATCH net-next 07/14] net: ethernet: mtk_eth_soc: use larger burst size for QDMA TX Ilya Lipnitskiy
2021-04-22  4:09 ` [PATCH net-next 08/14] net: ethernet: mtk_eth_soc: increase DMA ring sizes Ilya Lipnitskiy
2021-04-22  4:09 ` [PATCH net-next 09/14] net: ethernet: mtk_eth_soc: implement dynamic interrupt moderation Ilya Lipnitskiy
2021-04-22  4:09 ` Ilya Lipnitskiy [this message]
2021-04-22  4:09 ` [PATCH net-next 11/14] net: ethernet: mtk_eth_soc: only read the full RX descriptor if DMA is done Ilya Lipnitskiy
2021-04-22  4:09 ` [PATCH net-next 12/14] net: ethernet: mtk_eth_soc: reduce unnecessary interrupts Ilya Lipnitskiy
2021-04-22 16:26   ` Jakub Kicinski
2021-04-23  4:20     ` Ilya Lipnitskiy
2021-04-22  4:09 ` [PATCH net-next 13/14] net: ethernet: mtk_eth_soc: set PPE flow hash as skb hash if present Ilya Lipnitskiy
2021-04-22  4:09 ` [PATCH net-next 14/14] net: ethernet: mtk_eth_soc: use iopoll.h macro for DMA init Ilya Lipnitskiy
2021-04-22 12:20   ` Andrew Lunn
2021-04-22 12:23 ` [PATCH net-next 00/14] mtk_eth_soc: fixes and performance improvements Andrew Lunn
2021-04-23  4:18   ` Ilya Lipnitskiy

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