Re: Intel flash and cfi_probe.c

From: Bill Gatliff <bgat@billgatliff.com>
To: Dan Post <djp.mtd@onemyth.net>
Cc: linux-mtd@lists.infradead.org
Subject: Re: Intel flash and cfi_probe.c
Date: Tue, 20 Jan 2004 19:29:55 -0600	[thread overview]
Message-ID: <400DD613.80601@billgatliff.com> (raw)
In-Reply-To: <20040120215050.M62159@onemyth.net>

Dan:

I've seen similar behavior with the J flashes, see my posts from a 
couple of days ago.  My temporary workaround was to issue my own 0xff in 
my map driver functions.  :^(

I noticed the F0's, but didn't wade into the datasheet enough to spot 
that as an issue...

b.g.

Dan Post wrote:

>Hi,
>
>I was looking at the cfi_probe.c file, and noticed that there are numerous
>'0xF0' commands to flash (theoretically to put the flash back into read array
>mode).  This is incorrect in terms of Intel flash; according to the datasheets
>for L18/30 and K3/18, the "read array" command is 0xFF.
>
>Normally, it would work fine (by virtue of accident, the state machine is
>coherent enough not to break after the probe), except in cases of XIP (based
>on dwmw2's code, which I have been working on and will send out probably this
>week).  It breaks the system then because 0xF0 doesn't really put an Intel
>chip into read array, so when you enable intterupts, you schedule to a
>function running out of flash, which happens to be in status mode.... == big
>bad no-run, i.e. you freeze.
>
>(Specifically, it blows up on L*...  though it seemed to "work" on K*, that
>may just be an accident or compatibility mode that wasn't put into L*.  Or
>maybe I munged my code somehow and something magically changed.  It's not in
>the datasheets, so the behavior could change at any time.  When I changed the
>0xF0's to 0xFF's, it worked on L*.)
>
>I assume that the 0xF0 is for AMD flash (a datasheet I checked out confirms
>this).  For the cfi_probe.c file to be "proper", it needs to issue 0xFF to
>Intel flash, and 0xF0 for AMD.  (Any other chips using different commands??)
>
>What would happen if we issued an 0xF0;0xFF to an AMD chip?  Or 0xFF;0xF0? 
>Any AMD chip-heads care to answer?  It looks like it will "work" on Intel chips...
>
>At any rate, either there needs to be a clever hack like that, or the
>cfi_probe.c facilities need to be refactored so they know which command to
>issue to flash.
>
>Dan
>
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>  
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-- 
Bill Gatliff
So what part of make clean all install do you not understand?
bgat@billgatliff.com