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Message-ID: <4CD317E2.9090504@eukrea.com>
Date: Thu, 04 Nov 2010 21:30:26 +0100
From: Eric Bénard <eric@...rea.com>
To: Nguyen Dinh-R00091 <R00091@...escale.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 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.
Eric
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