From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from ns.sysgo.de ([213.68.67.98] helo=mailgate.sysgo.de)
	by canuck.infradead.org with esmtp (Exim 4.42 #1 (Red Hat Linux))
	id 1CSd9Q-0001wj-G6
	for linux-mtd@lists.infradead.org; Fri, 12 Nov 2004 10:15:50 -0500
Message-ID: <4194D39A.9000700@sysgo.de>
Date: Fri, 12 Nov 2004 16:15:38 +0100
From: Alexander Hoffmann <ahoffmann@sysgo.de>
MIME-Version: 1.0
To: linux-mtd@lists.infradead.org
References: <418F5E68.3010200@sysgo.de>	
	<20041108120624.GE13105@home.fluff.org>
	<418F6CA7.6000808@sysgo.de> <1099943453.10812.16.camel@tubarao>
In-Reply-To: <1099943453.10812.16.camel@tubarao>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: eauth@softsys.co.at, tharbaugh@lnxi.com
Subject: Re: Usage of MTD_UADDR_UNNECESSARY broken?
List-Id: Linux MTD discussion mailing list <linux-mtd.lists.infradead.org>
List-Unsubscribe: <http://lists.infradead.org/mailman/listinfo/linux-mtd>,
	<mailto:linux-mtd-request@lists.infradead.org?subject=unsubscribe>
List-Archive: <http://lists.infradead.org/pipermail/linux-mtd>
List-Post: <mailto:linux-mtd@lists.infradead.org>
List-Help: <mailto:linux-mtd-request@lists.infradead.org?subject=help>
List-Subscribe: <http://lists.infradead.org/mailman/listinfo/linux-mtd>,
	<mailto:linux-mtd-request@lists.infradead.org?subject=subscribe>

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[]?