netdev - Re: [PATCH/RFC v6 net-next] ravb: Add dma queue interrupt support

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Message-ID: <56D4AA63.6030203@cogentembedded.com>
Date:	Mon, 29 Feb 2016 23:30:27 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Yoshihiro Kaneko <ykaneko0929@...il.com>, netdev@...r.kernel.org
Cc:	"David S. Miller" <davem@...emloft.net>,
	Simon Horman <horms@...ge.net.au>,
	Magnus Damm <magnus.damm@...il.com>,
	linux-renesas-soc@...r.kernel.org, linux-sh@...r.kernel.org
Subject: Re: [PATCH/RFC v6 net-next] ravb: Add dma queue interrupt support

Hello.

On 02/28/2016 06:41 PM, Yoshihiro Kaneko wrote:

> From: Kazuya Mizuguchi <kazuya.mizuguchi.ks@...esas.com>
>
> This patch supports the following interrupts.
>
> - One interrupt for multiple (timestamp, error, gPTP)
> - One interrupt for emac
> - Four interrupts for dma queue (best effort rx/tx, network control rx/tx)
>
> This patch improve efficiency of the interrupt handler by adding the
> interrupt handler corresponding to each interrupt source described
> above. Additionally, it reduces the number of times of the access to
> EthernetAVB IF.
> Also this patch prevent this driver depends on the whim of a boot loader.
>
> [ykaneko0929@...il.com: define bit names of registers]
> [ykaneko0929@...il.com: add comment for gen3 only registers]
> [ykaneko0929@...il.com: fix coding style]
> [ykaneko0929@...il.com: update changelog]
> [ykaneko0929@...il.com: gen3: fix initialization of interrupts]
> [ykaneko0929@...il.com: gen3: fix clearing interrupts]
> [ykaneko0929@...il.com: gen3: add helper function for request_irq()]
> [ykaneko0929@...il.com: gen3: remove IRQF_SHARED flag for request_irq()]
> [ykaneko0929@...il.com: revert ravb_close() and ravb_ptp_stop()]
> [ykaneko0929@...il.com: avoid calling free_irq() to non-hooked interrupts]
> [ykaneko0929@...il.com: make NC/BE interrupt handler a function]
> [ykaneko0929@...il.com: make timestamp interrupt handler a function]
> [ykaneko0929@...il.com: timestamp interrupt is handled in multiple
>   interrupt handler instead of dma queue interrupt handler]
> Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@...esas.com>
> Signed-off-by: Yoshihiro Kaneko <ykaneko0929@...il.com>

    OK, you are very close now! Just a few comments...

[...]
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index c936682..22ef65d 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
[...]
> @@ -697,6 +726,47 @@ static void ravb_error_interrupt(struct net_device *ndev)
>   	}
>   }
>
> +static bool ravb_queue_interrupt(struct net_device *ndev, int q,
> +				 u32 ris0, u32 *ric0, u32 tis, u32 *tic)
> +{
> +	struct ravb_private *priv = netdev_priv(ndev);
> +

    Perhaps it makes sense to read the RI[CS]0/TI[CS] here instead of passing 
them (by reference)?

[...]
> @@ -714,42 +784,21 @@ static irqreturn_t ravb_interrupt(int irq, void *dev_id)
>   		u32 ric0 = ravb_read(ndev, RIC0);
>   		u32 tis  = ravb_read(ndev, TIS);
>   		u32 tic  = ravb_read(ndev, TIC);
> -		int q;
>
>   		/* Timestamp updated */
> -		if (tis & TIS_TFUF) {
> -			ravb_write(ndev, ~TIS_TFUF, TIS);
> -			ravb_get_tx_tstamp(ndev);
> +		if (ravb_timestamp_interrupt(ndev, tis))
>   			result = IRQ_HANDLED;
> -		}
>
>   		/* Network control and best effort queue RX/TX */
> -		for (q = RAVB_NC; q >= RAVB_BE; q--) {
> -			if (((ris0 & ric0) & BIT(q)) ||
> -			    ((tis  & tic)  & BIT(q))) {
> -				if (napi_schedule_prep(&priv->napi[q])) {
> -					/* Mask RX and TX interrupts */
> -					ric0 &= ~BIT(q);
> -					tic &= ~BIT(q);
> -					ravb_write(ndev, ric0, RIC0);
> -					ravb_write(ndev, tic, TIC);
> -					__napi_schedule(&priv->napi[q]);
> -				} else {
> -					netdev_warn(ndev,
> -						    "ignoring interrupt, rx status 0x%08x, rx mask 0x%08x,\n",
> -						    ris0, ric0);
> -					netdev_warn(ndev,
> -						    "                    tx status 0x%08x, tx mask 0x%08x.\n",
> -						    tis, tic);
> -				}
> -				result = IRQ_HANDLED;
> -			}
> -		}
> +		if (ravb_queue_interrupt(ndev, RAVB_NC, ris0, &ric0, tis, &tic))
> +			result = IRQ_HANDLED;
> +		if (ravb_queue_interrupt(ndev, RAVB_BE, ris0, &ric0, tis, &tic))
> +			result = IRQ_HANDLED;

    Hmm, perhaps unrolling wasn't such a great idea... we can't use || here as 
it would be short-circuited. :-(

[...]
> +static irqreturn_t ravb_rx_tx_interrupt(int irq, void *dev_id, int ravb_queue)

    Please, please shorten this 'ravb_queue'...
    Also, would make sense to rename it to ravb_dma_interrupt()...

[...]

    Unfortunately, I still can't do a full gen2 regression testing as both Alt 
and Porter boards don't work with the recent kernel due to AVB_MDIO stuck at 
1... But perhaps such testing isn't even necessary.

MBR, Sergei