Re: peak_pci: TX Frame Loss

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 12/02/2015 08:19 PM, Oliver Hartkopp wrote:
>> diff --git a/drivers/net/can/sja1000/sja1000.c b/drivers/net/can/sja1000/sja1000.c
>> index f968d1e..b5115c2 100644
>> --- a/drivers/net/can/sja1000/sja1000.c
>> +++ b/drivers/net/can/sja1000/sja1000.c
>> @@ -93,6 +93,7 @@ static void sja1000_write_cmdreg(struct sja1000_priv *priv, u8 val)
>>  	spin_lock_irqsave(&priv->cmdreg_lock, flags);
>>  	priv->write_reg(priv, SJA1000_CMR, val);
>>  	priv->read_reg(priv, SJA1000_SR);
>> +	udelay(10);
>>  	spin_unlock_irqrestore(&priv->cmdreg_lock, flags);
>>  }
> 
> Hi Andri,
> 
> looking at the code above I wonder whether the
> 
> 	priv->read_reg(priv, SJA1000_SR);
> 
> is a bad hack anyway.
> 
> The read_reg() becomes readb(priv->reg_base + (port << 2)) in peak_pci.c and
> the result is never used.
> 
> What if the entire operation gets 'optimized' at some point?

readX() calls are never optimized out.

> Can you check what happens if you just replace the priv->read_reg() with your
> udelay(10) call?

Marc

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