Subject: Re: [PATCH net-next v2 2/4] can: cc770: add legacy ISA bus driver for the CC770 and AN82527

From: Wolfgang Grandegger <[email-masked]>
Date: Wed, 04 Jan 2012 14:10:52 +0100

Hi Wolfgang,

On 12/31/2011 10:39 AM, Wolfgang Zarre wrote:
> Hello Wolfgang,
> 
>> Hello Wolfgang,
>>> Hi Wolfgang,
>>>
>>> On 12/21/2011 07:32 PM, Wolfgang Zarre wrote:
>>>> Hello Wolfgang,
>>> ...
>>>
>>>
>>> Again, please check if you have netif_start_queue() at the end of the
>>> open function.
>>>
>>
>> As said I'm using eec921ac28fde243456078a557768808d93d94a3
>>
>> However, I'll try further to investigate that issue due the fact
>> having it
>> running with my lincan without problems and therefore it should be
>> possible
>> to find the problem.
>>
> 
> I found the problem which was then at the end quite simple to understand
> why it
> get stuck due the fact not receiving an interrupt for TX and due that no
> reactivation of the queue.
> 
> I think that maybe also the hacks in the TX functions are obsolete with the
> fix assuming that the repeated interrupts just happen by indirect access.

OK, to understand you correctly...

> Here my fix which worked for me:
> --------------------------------------------------------------------------------------------------------
> 
> diff --git a/drivers/net/can/cc770/cc770.c b/drivers/net/can/cc770/cc770.c
> index 2d12f89..dad6707 100644
> --- a/drivers/net/can/cc770/cc770.c
> +++ b/drivers/net/can/cc770/cc770.c
> @@ -460,15 +460,6 @@ static netdev_tx_t cc770_start_xmit(struct sk_buff
> *skb, struct net_device *dev)
> 
>      stats->tx_bytes += dlc;
> 
> -
> -    /*
> -     * HM: We had some cases of repeated IRQs so make sure the
> -     * INT is acknowledged I know it's already further up, but
> -     * doing again fixed the issue
> -     */
> -    cc770_write_reg(priv, msgobj[mo].ctrl0,
> -            MSGVAL_UNC | TXIE_UNC | RXIE_UNC | INTPND_RES);
> -
>      return NETDEV_TX_OK;
>  }
> 
> @@ -689,12 +680,6 @@ static void cc770_tx_interrupt(struct net_device
> *dev, unsigned int o)
>      /* Nothing more to send, switch off interrupts */
>      cc770_write_reg(priv, msgobj[mo].ctrl0,
>              MSGVAL_RES | TXIE_RES | RXIE_RES | INTPND_RES);
> -    /*
> -     * We had some cases of repeated IRQ so make sure the
> -     * INT is acknowledged
> -     */
> -    cc770_write_reg(priv, msgobj[mo].ctrl0,
> -            MSGVAL_UNC | TXIE_UNC | RXIE_UNC | INTPND_RES);
> 
>      stats->tx_packets++;
>      can_get_echo_skb(dev, 0);
> diff --git a/drivers/net/can/cc770/cc770_isa.c
> b/drivers/net/can/cc770/cc770_isa.c
> index 4be5fe2..48fc128 100644
> --- a/drivers/net/can/cc770/cc770_isa.c
> +++ b/drivers/net/can/cc770/cc770_isa.c
> @@ -148,8 +148,7 @@ static void cc770_isa_port_write_reg_indirect(const
> struct cc770_priv *priv,
>  {
>      unsigned long base = (unsigned long)priv->reg_base;
> 
> -    outb(reg, base);
> -    outb(val, base + 1);
> +    outw( reg + ( val << 8), base);

That modification does fix your problem, right? The others above don't
help nor harm but we don't know if it's really realted to the same
problem. I wll dig a bit deeper.

>  }
> 
>  static int __devinit cc770_isa_probe(struct platform_device *pdev)
> 
> ---------------------------------------------------------------------------------------------
> 
> 
> 
> Please let me know if this is OK for You, maybe You can do some tests as
> well.

My board does not use indirect accesses.

> Would continue then with further tests regarding error conditions, however
> I realised another small issue with dropped packages at reception.
> 
> As soon as You read the first time from the socket and then You stop
> reading
> the packages are not counted as 'dropped' any more which is IMHO not
> correct
> because as soon as You stop reading they should be counted as dropped
> again.

Will have a closer look now...

Wolfgang.