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Message-ID: <86A0E76937111F4C92FABEC0A20988510523CF07@az33exm21>
Date: Thu, 4 Nov 2010 14:30:14 -0700
From: Nguyen Dinh-R00091 <R00091@...escale.com>
To: Eric Bénard <eric@...rea.com>
CC: <linux-kernel@...r.kernel.org>, <amit.kucheria@...onical.com>,
<linux@....linux.org.uk>, <s.hauer@...gutronix.de>,
<grant.likely@...retlab.ca>,
<linux-arm-kernel@...ts.infradead.org>, <daniel@...aq.de>,
<u.kleine-koenig@...gutronix.de>,
Zhang Lily-R58066 <R58066@...escale.com>,
<valentin.longchamp@...l.ch>
Subject: RE: [PATCH 2/2] ARM: imx: Add mx53 support to common msl functions.
Hi Eric,
>-----Original Message-----
>From: Nguyen Dinh-R00091
>Sent: Thursday, November 04, 2010 4:24 PM
>To: 'Eric Bénard'
>Cc: linux-kernel@...r.kernel.org; amit.kucheria@...onical.com; linux@....linux.org.uk;
>s.hauer@...gutronix.de; grant.likely@...retlab.ca; linux-arm-kernel@...ts.infradead.org;
>daniel@...aq.de; u.kleine-koenig@...gutronix.de; Zhang Lily-R58066; valentin.longchamp@...l.ch
>Subject: RE: [PATCH 2/2] ARM: imx: Add mx53 support to common msl functions.
>
>Hi Eric,
>
>>-----Original Message-----
>>From: linux-kernel-owner@...r.kernel.org [mailto:linux-kernel-owner@...r.kernel.org] On Behalf Of
>Eric
>>Bénard
>>Sent: Thursday, November 04, 2010 3:30 PM
>>To: Nguyen Dinh-R00091
>>Cc: linux-kernel@...r.kernel.org; amit.kucheria@...onical.com; linux@....linux.org.uk;
>>s.hauer@...gutronix.de; grant.likely@...retlab.ca; linux-arm-kernel@...ts.infradead.org;
>>daniel@...aq.de; u.kleine-koenig@...gutronix.de; Zhang Lily-R58066; valentin.longchamp@...l.ch
>>Subject: Re: [PATCH 2/2] ARM: imx: Add mx53 support to common msl functions.
>>
>>Hi Dinh,
>>
>>Le 04/11/2010 20:21, Nguyen Dinh-R00091 a écrit :
>>> Reading the ROM code is probably the most reliable way to get the correct
>>> silicon revision. Because the ROM that is on the chip is "most likely"
>>> up-to-date with the silicon. "Most likely" means that 95% of the time, when
>>> you get a new silicon, the ROM code will get updated. There is still a
>>> chance that a new silicon will not require a ROM update.
>>>
>>> Also the other reason is that sometimes the fuses that identify the silicon
>>> revision that are used by the IIM are sometimes not blown to reflect the
>>> correct revision in pre-production parts. MX51 is a post production part,
>>> so in theory, the fuses are blown correctly. But since we made MX51 boards
>>> available prior to going into production, reading from the IIM is not as
>>> reliable as reading the ROM.
>>>
>>Don't you think we should use the documented register which (if we believe the
>>documentation) should be 100% reliable for production CPU instead of this
>>undocumented method which from what you say is 95% reliable and here to handle
>>the case of pre production CPU ?
>>
>>The same problem occured on i.MX35 silicon 2.1 which where not correctly
>>detected using the ROM code.
>>
>
>Would you agree to this approach? Read the IIM register and the ROM code, if the IIM and ROM agree,
>then no issue. But if ROM and IIM disagree, we would go with whatever is the latest Revision?
Nevermind on this. I just got an answer that the IIM register is guaranteed to be a correct silicon revision and no fuses need to be blown. I'll send out a patch for this soon.
Thanks,
Dinh
>
>>Eric
>>--
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