Re: Usage of MTD_UADDR_UNNECESSARY broken?

[Alexander Hoffmann <ahoffmann@sysgo.de>]

Erwin Authried wrote:

>Am Fre, den 12.11.2004 schrieb Alexander Hoffmann um 16:15:
>  
>
>>Hi Thayne,
>>
>>sorry for the delayed response.
>>
>>Thayne Harbaugh wrote:
>>
>>    
>>
>>>On Mon, 2004-11-08 at 13:55 +0100, Alexander Hoffmann wrote:
>>> 
>>>
>>>      
>>>
>>>>Ben Dooks wrote:
>>>>
>>>>   
>>>>
>>>>        
>>>>
>>>>>On Mon, Nov 08, 2004 at 12:54:16PM +0100, Alexander Hoffmann wrote:
>>>>>     
>>>>>
>>>>>          
>>>>>
>>>>>>Hi everyone,
>>>>>>
>>>>>>can anybody please explain me the exact difference between 
>>>>>>MTD_UADDR_DONT_CARE and MTD_UADDR_UNNECESSARY .
>>>>>>Because if I use MTD_UADDR_UNNECESSARY an not existing field in the 
>>>>>>unlock_addrs array is beeing referenced
>>>>>>(/drivers/mtd/chips/jedec_probe.c, function cfi_jedec_setup, line 1740):
>>>>>>
>>>>>>/* Mask out address bits which are smaller than the device type */
>>>>>>mask = ~(p_cfi->device_type-1);
>>>>>>p_cfi->addr_unlock1 = unlock_addrs[uaddr].addr1 & mask;
>>>>>>p_cfi->addr_unlock2 = unlock_addrs[uaddr].addr2 & mask;
>>>>>>       
>>>>>>
>>>>>>            
>>>>>>
>>>>>hmm, thought this masking had been eliminated in later copies of
>>>>>the mtd code?
>>>>>     
>>>>>
>>>>>          
>>>>>
>>>Yes, the masking has been eliminated, but someone left the comment in
>>>(doh!).
>>>
>>> 
>>>
>>>      
>>>
>>>>Ok, you are right. But this doesn't change the fact that
>>>>
>>>>unlock_addrs[uaddr].addr1
>>>>
>>>>refers to an nonexisting field in the unlock_addrs array.
>>>>   
>>>>
>>>>        
>>>>
>>>I don't see how the code you that you described is being reached.  It
>>>looks like the start of jedec_probe_chip() checks for UNNECESSARY and
>>>returns 0 (although I would expect 1) and so cfi_jedec_setup() should
>>>never be called with UNNECESSARY (even for subsequent chips).
>>>
>>>      
>>>
>>I am working with the cdb89712 development board from cirrus. This board 
>>has an "Intel 28F320B3B" chip
>>(device_id  =  0x8897). Apparently, jedec_probe() finds 
>>MTD_UADDR_0x0555_0x02AA.
>>for this chip, while the jedec_table[] specifies it as 
>>MTD_UADDR_UNNECESSARY.
>>Since the probed unlock type is overidden by the static one, the code 
>>_does_ reach
>>jedec_setup().
>>
>>What I haven't really understood is this: if the code refuses chips of  
>>type UNNECESSARY
>>(the return code 0 from jedec_probe() is an error), then why are so many 
>>chips declared
>>as UNECESSARY in jedec_table[]?
>>    
>>
>
>MTD_UADDR_UNNECESSARY is used to specify that the chip does not need any
>unlock sequence at all. The "return 0" statement near the  top of
>jedec_probe_chip is executed if all possible unlock sequences have been
>tried without finding a match in jedec table, thus it indicates an
>error. It's correct that your chip finds a match with
>MTD_UADDR_0x0555_0x02aa, because that's the first try and the chip
>doesn't care at all about the unlock sequence. 
>  
>
Does this mean, that the "return 0" statement at the beginning of 
jedec_probe_chip() is only reached
when my chip isn't lsited in jedec_table[] ?
If it is listed , there will always be a match and therefore the 
functions cfi_jedec_setup() and finfo_uaddr()
will be called !?

Alex.