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SubjectRE: [PATCH 2/2] ARM: imx: Add mx53 support to common msl functions.
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Hi Eric,

>-----Original Message-----
>From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Eric
>Bénard
>Sent: Thursday, November 04, 2010 3:30 PM
>To: Nguyen Dinh-R00091
>Cc: linux-kernel@vger.kernel.org; amit.kucheria@canonical.com; linux@arm.linux.org.uk;
>s.hauer@pengutronix.de; grant.likely@secretlab.ca; linux-arm-kernel@lists.infradead.org;
>daniel@caiaq.de; u.kleine-koenig@pengutronix.de; Zhang Lily-R58066; valentin.longchamp@epfl.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?

>Eric
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