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

From: Wolfgang Zarre <[email-masked]>
Date: Tue, 10 Jan 2012 13:41:21 +0100

Hello David,
>
>> cc770_isa_port_write_reg_indirect(const struct cc770_priv *priv,
>>    						int reg, u8 val)
>>    {
>>    	unsigned long base = (unsigned long)priv->reg_base;
>> +	unsigned long flags;
>>
>> +	spin_lock_irqsave(&outb_lock, flags);
>>    	outb(reg, base);
>>    	outb(val, base + 1);
>> +	spin_unlock_irqrestore(&outb_lock, flags);	
>
> Is there a 'read_reg_indirect' function??

Yes, there is.

> If so it also needs to use the same mutex.

Actually, I don't think that we have a problem with mutex
beside that it's using just one inb() statement but having
for sure with an interrupt between both outb() statements which
seems to be critical for the cc770.

However, if inb() or outb() can be interrupted then it would be
an issue.

> I'd double check all references to the 'reg_base' field.
>
> 	David
>
>

Wolfgang