From: Troy Kisky <troy.ki...@boundarydevices.com> Sent: Thursday, February 25,
2016 8:37 AM
> To: netdev@vger.kernel.org; da...@davemloft.net; b38...@freescale.com
> Cc: fabio.este...@freescale.com; l.st...@pengutronix.de; and...@lunn.ch;
> trem...@gmail.com; li...@arm.linux.org.uk; linux-arm-
> ker...@lists.infradead.org; l...@boundarydevices.com; shawn...@kernel.org;
> johan...@sipsolutions.net; stillcompil...@gmail.com;
> sergei.shtyl...@cogentembedded.com; a...@arndb.de; Troy Kisky
> <troy.ki...@boundarydevices.com>
> Subject: [PATCH net-next V2 04/16] net: fec: reduce interrupts
>
> By clearing the NAPI interrupts in the NAPI routine and not in the interrupt
> handler, we can reduce the number of interrupts. We also don't need any
> status variables as the registers are still valid.
>
> Also, notice that if budget pkts are received, the next call to
> fec_enet_rx_napi
> will now continue to receive the previously pending packets.
>
> Signed-off-by: Troy Kisky <troy.ki...@boundarydevices.com>
> ---
> drivers/net/ethernet/freescale/fec.h | 6 +-
> drivers/net/ethernet/freescale/fec_main.c | 127 ++++++++++++----------------
> --
> 2 files changed, 50 insertions(+), 83 deletions(-)
>
> diff --git a/drivers/net/ethernet/freescale/fec.h
> b/drivers/net/ethernet/freescale/fec.h
> index 195122e..001200b 100644
> --- a/drivers/net/ethernet/freescale/fec.h
> +++ b/drivers/net/ethernet/freescale/fec.h
> @@ -505,11 +505,7 @@ struct fec_enet_private {
>
> unsigned int total_tx_ring_size;
> unsigned int total_rx_ring_size;
> -
> - unsigned long work_tx;
> - unsigned long work_rx;
> - unsigned long work_ts;
> - unsigned long work_mdio;
> + uint events;
>
> struct platform_device *pdev;
>
> diff --git a/drivers/net/ethernet/freescale/fec_main.c
> b/drivers/net/ethernet/freescale/fec_main.c
> index c517194..4a218b9 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -70,8 +70,6 @@ static void fec_enet_itr_coal_init(struct net_device
> *ndev);
>
> #define DRIVER_NAME "fec"
>
> -#define FEC_ENET_GET_QUQUE(_x) ((_x == 0) ? 1 : ((_x == 1) ? 2 : 0))
> -
> /* Pause frame feild and FIFO threshold */
> #define FEC_ENET_FCE (1 << 5)
> #define FEC_ENET_RSEM_V 0x84
> @@ -1257,21 +1255,6 @@ static void fec_txq(struct net_device *ndev, struct
> fec_enet_private *fep,
> writel(0, txq->bd.reg_desc_active);
> }
>
> -static void
> -fec_enet_tx(struct net_device *ndev)
> -{
> - struct fec_enet_private *fep = netdev_priv(ndev);
> - struct fec_enet_priv_tx_q *txq;
> - u16 queue_id;
> - /* First process class A queue, then Class B and Best Effort queue */
> - for_each_set_bit(queue_id, &fep->work_tx, FEC_ENET_MAX_TX_QS)
> {
> - clear_bit(queue_id, &fep->work_tx);
> - txq = fep->tx_queue[FEC_ENET_GET_QUQUE(queue_id)];
> - fec_txq(ndev, fep, txq);
> - }
> - return;
> -}
> -
> static int
> fec_enet_new_rxbdp(struct net_device *ndev, struct bufdesc *bdp, struct
> sk_buff *skb) { @@ -1504,92 +1487,80 @@ rx_processing_done:
> return pkt_received;
> }
>
> -static int
> -fec_enet_rx(struct net_device *ndev, int budget) -{
> - int pkt_received = 0;
> - u16 queue_id;
> - struct fec_enet_private *fep = netdev_priv(ndev);
> - struct fec_enet_priv_rx_q *rxq;
> -
> - for_each_set_bit(queue_id, &fep->work_rx, FEC_ENET_MAX_RX_QS)
> {
> - clear_bit(queue_id, &fep->work_rx);
> - rxq = fep->rx_queue[FEC_ENET_GET_QUQUE(queue_id)];
> - pkt_received += fec_rxq(ndev, fep, rxq, budget -
> pkt_received);
> - }
> - return pkt_received;
> -}
> -
> -static bool
> -fec_enet_collect_events(struct fec_enet_private *fep, uint int_events) -{
> - if (int_events == 0)
> - return false;
> -
> - if (int_events & FEC_ENET_RXF_0)
> - fep->work_rx |= (1 << 2);
> - if (int_events & FEC_ENET_RXF_1)
> - fep->work_rx |= (1 << 0);
> - if (int_events & FEC_ENET_RXF_2)
> - fep->work_rx |= (1 << 1);
> -
> - if (int_events & FEC_ENET_TXF_0)
> - fep->work_tx |= (1 << 2);
> - if (int_events & FEC_ENET_TXF_1)
> - fep->work_tx |= (1 << 0);
> - if (int_events & FEC_ENET_TXF_2)
> - fep->work_tx |= (1 << 1);
> -
> - return true;
> -}
> -
> static irqreturn_t
> fec_enet_interrupt(int irq, void *dev_id) {
> struct net_device *ndev = dev_id;
> struct fec_enet_private *fep = netdev_priv(ndev);
> - uint int_events;
> - irqreturn_t ret = IRQ_NONE;
> + uint eir = readl(fep->hwp + FEC_IEVENT);
> + uint int_events = eir & readl(fep->hwp + FEC_IMASK);
>
> - int_events = readl(fep->hwp + FEC_IEVENT);
> - writel(int_events, fep->hwp + FEC_IEVENT);
> - fec_enet_collect_events(fep, int_events);
> -
> - if ((fep->work_tx || fep->work_rx) && fep->link) {
> - ret = IRQ_HANDLED;
> + if (!int_events)
> + return IRQ_NONE;
>
> + if (int_events & (FEC_ENET_RXF | FEC_ENET_TXF)) {
> if (napi_schedule_prep(&fep->napi)) {
> /* Disable the NAPI interrupts */
> writel(FEC_NAPI_IMASK, fep->hwp + FEC_IMASK);
> __napi_schedule(&fep->napi);
> + int_events &= ~(FEC_ENET_RXF | FEC_ENET_TXF);
> + if (!int_events)
> + return IRQ_HANDLED;
> + } else {
> + fep->events |= int_events;
> + pr_info("%s: couldn't schedule NAPI\n", __func__);
> }
> }
>
> - if (int_events & FEC_ENET_MII) {
> - ret = IRQ_HANDLED;
> + writel(int_events, fep->hwp + FEC_IEVENT);
> + if (int_events & FEC_ENET_MII)
> complete(&fep->mdio_done);
> - }
>
> - if (fep->ptp_clock)
> + if ((int_events & FEC_ENET_TS_TIMER) && fep->ptp_clock)
> fec_ptp_check_pps_event(fep);
> -
> - return ret;
> + return IRQ_HANDLED;
> }
>
> static int fec_enet_rx_napi(struct napi_struct *napi, int budget) {
> struct net_device *ndev = napi->dev;
> struct fec_enet_private *fep = netdev_priv(ndev);
> - int pkts;
> -
> - pkts = fec_enet_rx(ndev, budget);
> + int pkts = 0;
> + uint events;
>
> - fec_enet_tx(ndev);
> + do {
> + events = readl(fep->hwp + FEC_IEVENT);
> + if (fep->events) {
> + events |= fep->events;
> + fep->events = 0;
> + }
> + events &= FEC_ENET_RXF | FEC_ENET_TXF;
> + if (!events) {
> + if (budget) {
> + napi_complete(napi);
> + writel(FEC_DEFAULT_IMASK, fep->hwp +
> FEC_IMASK);
> + }
> + return pkts;
> + }
>
> - if (pkts < budget) {
> - napi_complete(napi);
> - writel(FEC_DEFAULT_IMASK, fep->hwp + FEC_IMASK);
> - }
> + writel(events, fep->hwp + FEC_IEVENT);
> + if (events & FEC_ENET_RXF_1)
> + pkts += fec_rxq(ndev, fep, fep->rx_queue[1],
> + budget - pkts);
> + if (events & FEC_ENET_RXF_2)
> + pkts += fec_rxq(ndev, fep, fep->rx_queue[2],
> + budget - pkts);
> + if (events & FEC_ENET_RXF_0)
> + pkts += fec_rxq(ndev, fep, fep->rx_queue[0],
> + budget - pkts);
> + if (events & FEC_ENET_TXF_1)
> + fec_txq(ndev, fep, fep->tx_queue[1]);
> + if (events & FEC_ENET_TXF_2)
> + fec_txq(ndev, fep, fep->tx_queue[2]);
> + if (events & FEC_ENET_TXF_0)
> + fec_txq(ndev, fep, fep->tx_queue[0]);
> + } while (pkts < budget);
> + fep->events |= events & FEC_ENET_RXF; /* save for next callback
Here seems ugly, if the first time fep->events is FEC_ENET_RXF, suppose
FEC_IEVENT is zero when call the second napi callback, fec_rxq() will be
called again after "events |= fep->events;", it is not necessary.
If you clear FEC_ENET_TXF, FEC_ENET_RXF bit in ENET_EIMR, there have no TXF,
RXF interrupt to cpu. So I don't think the patch can reduce interrupt numbers.
I don't like the patch. I suggest to separate TX and RX into two NAPI context,
for tx path call .netif_tx_napi_add() to init one NAPI context.
Regards,
Andy
> */
> return pkts;
> }
>
> --
> 2.5.0
