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Message-ID: <56D710EB.5000201@boundarydevices.com>
Date: Wed, 2 Mar 2016 09:12:27 -0700
From: Troy Kisky <troy.kisky@...ndarydevices.com>
To: Fugang Duan <fugang.duan@....com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"davem@...emloft.net" <davem@...emloft.net>,
"b38611@...escale.com" <b38611@...escale.com>
Cc: "fabio.estevam@...escale.com" <fabio.estevam@...escale.com>,
"l.stach@...gutronix.de" <l.stach@...gutronix.de>,
"andrew@...n.ch" <andrew@...n.ch>,
"tremyfr@...il.com" <tremyfr@...il.com>,
"linux@....linux.org.uk" <linux@....linux.org.uk>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"laci@...ndarydevices.com" <laci@...ndarydevices.com>,
"shawnguo@...nel.org" <shawnguo@...nel.org>,
"johannes@...solutions.net" <johannes@...solutions.net>,
"stillcompiling@...il.com" <stillcompiling@...il.com>,
"sergei.shtylyov@...entembedded.com"
<sergei.shtylyov@...entembedded.com>,
"arnd@...db.de" <arnd@...db.de>
Subject: Re: [PATCH net-next V2 04/16] net: fec: reduce interrupts
On 3/2/2016 8:13 AM, Fugang Duan wrote:
> From: Troy Kisky <troy.kisky@...ndarydevices.com> Sent: Thursday, February 25, 2016 8:37 AM
>> To: netdev@...r.kernel.org; davem@...emloft.net; b38611@...escale.com
>> Cc: fabio.estevam@...escale.com; l.stach@...gutronix.de; andrew@...n.ch;
>> tremyfr@...il.com; linux@....linux.org.uk; linux-arm-
>> kernel@...ts.infradead.org; laci@...ndarydevices.com; shawnguo@...nel.org;
>> johannes@...solutions.net; stillcompiling@...il.com;
>> sergei.shtylyov@...entembedded.com; arnd@...db.de; Troy Kisky
>> <troy.kisky@...ndarydevices.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.kisky@...ndarydevices.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);
>> -
> This is error in here. FEC compare timer event is not TS timer.
>
>
So when should fec_ptp_check_pps_event be called ? On every interrupt ?
If napi is active, it is going to be delayed for a very long time.
Should it be moved to the napi routine?
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