netdev - Re: [PATCH/RFC v5 net-next] ravb: Add dma queue interrupt support

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Message-ID: <56D4B02F.7030803@cogentembedded.com>
Date:	Mon, 29 Feb 2016 23:55:11 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Yoshihiro Kaneko <ykaneko0929@...il.com>
Cc:	netdev@...r.kernel.org, "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 list <linux-sh@...r.kernel.org>
Subject: Re: [PATCH/RFC v5 net-next] ravb: Add dma queue interrupt support

On 02/28/2016 05:13 PM, Yoshihiro Kaneko wrote:

>>> From: Kazuya Mizuguchi <kazuya.mizuguchi.ks@...esas.com>
>>>
>>> This patch supports the following interrupts.
>>>
>>> - One interrupt for multiple (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: 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]
>>> Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@...esas.com>
>>> Signed-off-by: Yoshihiro Kaneko <ykaneko0929@...il.com>
>>
>>
>> [...]
>>
>>> diff --git a/drivers/net/ethernet/renesas/ravb_main.c
>>> b/drivers/net/ethernet/renesas/ravb_main.c
>>> index c936682..1bec71e 100644
>>> --- a/drivers/net/ethernet/renesas/ravb_main.c
>>> +++ b/drivers/net/ethernet/renesas/ravb_main.c
>>
>> [...]
>>>
>>> @@ -697,6 +726,39 @@ static void ravb_error_interrupt(struct net_device
>>> *ndev)
>>>          }
>>>    }
>>>
>>> +static int ravb_nc_be_interrupt(struct net_device *ndev, int ravb_queue,
>>
>>
>>     I'd call this function e.g. ravb_queue_interrupt(). And make it return
>> 'bool' or even 'irqreturn_t' directly. And I'd suggest a shorter name for
>> the 'ravb_queue' parameter, like 'queue' or even 'q'...
>
> Agreed.
>
>>
>>> +                               u32 ris0, u32 *ric0, u32 tis, u32 *tic)
>>
>>
>>     You don't seem to need 'ric0' and 'tic' past the call sites, so no real
>> need to pass them by reference.
>
> When Rx/Tx interrupt for NC and BE is issued at the same time,
> this function is called twice (for NC, BE) from ravb_interrupt.
> The interrupt mask of NC set in the first call will be reset in the next
> call for BE. So it is necessary to keep the modified value of "ric0" and
> "tic".

    OK, but we still can simplify this by reading these registers right in 
ravb_queue_interrupt()...

[...]
>>> @@ -725,31 +787,15 @@ static irqreturn_t ravb_interrupt(int irq, void
>>> *dev_id)
>>>
>>>                  /* 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);
>>> -                               }
>>> +                       if (ravb_nc_be_interrupt(ndev, q, ris0, &ric0,
>>> tis,
>>> +                                                &tic))
>>>                                  result = IRQ_HANDLED;
>>> -                       }
>>>                  }
>>
>>
>>     Unroll this *for* loop please...

> OK.

    It was a bad idea actually, sorry...

[...]
>>> @@ -767,6 +813,73 @@ static irqreturn_t ravb_interrupt(int irq, void
[...]
>>> +static irqreturn_t ravb_dmaq_interrupt(int irq, void *dev_id, int
>>> ravb_queue)
>>
>>
>>     Perhaps, ravb_rx_tx_interrupt()?
>
> Agreed.

    And we still have ravb_dma_interrupt() unused, right?

[...]

> Thanks,
> kaneko

MBR, Sergei