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From: Wolfgang Denk <wd@denx.de>
To: u-boot@lists.denx.de
Subject: [U-Boot-Users] [PATCH 1/1] Fix I2C for m547x/548x and m5445x processors.
Date: Mon, 07 Jul 2008 20:02:17 +0200	[thread overview]
Message-ID: <20080707180217.B3DFA248FE@gemini.denx.de> (raw)
In-Reply-To: Your message of "Mon, 07 Jul 2008 18:17:45 +0200." <1215447465.12657.15.camel@localhost>

In message <1215447465.12657.15.camel@localhost> you wrote:
>
> I just extended the fsl_i2c.c driver that already uses a precomputed

Yes, I know. I never understood what such a  complicated  driver  for
sich  a  simple  protocol  was  good  for,  especially as we don't do
multimegabytepersecond transfers over such a bus.

> table to setup the fsl i2c. I haven't invented these values but just
> copied from the 547x and 5445x manuals. Furthermore, the h/w i2c is more
> accurate that the simple bitbanging.

Accurate? There is no requirement to be "accurate"  anywhere  in  the
I2C  protocol.  It  is  a simple, brain-dead protokol where timing is
highly uncritical. And given that we need it to read a few bytes from
EEPROM or RTC or similar I really see no  benefit  in  using  such  a
complicated driver.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
How many seconds are there in a year? If I tell you there are 3.155 x
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forget that, to within half a percent, pi seconds is a nanocentury.
                                                - Tom Duff, Bell Labs

  reply	other threads:[~2008-07-07 18:02 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-07-07 14:08 [U-Boot-Users] [COLDFIRE] Luigi 'Comio' Mantellini
2008-07-07 14:08 ` [U-Boot-Users] [PATCH 1/1] Fix I2C for m547x/548x and m5445x processors Luigi 'Comio' Mantellini
2008-07-07 14:59   ` Wolfgang Denk
2008-07-07 16:17     ` Luigi 'Comio' Mantellini
2008-07-07 18:02       ` Wolfgang Denk [this message]
2008-07-07 19:24         ` Luigi 'Comio' Mantellini
2008-07-09 13:22         ` Timur Tabi
  -- strict thread matches above, loose matches on Subject: below --
2008-07-07 14:11 [U-Boot-Users] [COLDFIRE] I2C patch 547x/548x cpus Luigi 'Comio' Mantellini
2008-07-07 14:11 ` [U-Boot-Users] [PATCH 1/1] Fix I2C for m547x/548x and m5445x processors Luigi 'Comio' Mantellini
2008-07-07 14:17 ` Luigi 'Comio' Mantellini
2008-07-09 13:25   ` Timur Tabi
2008-07-09 13:40     ` Luigi 'Comio' Mantellini

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