On Fri, 6 Feb 2009, Wolfgang Denk wrote:
Dear Guennadi Liakhovetski,
In message Pine.LNX.4.64.0902061002160.4970@axis700.grange you wrote:
Upon power on i.MX31 enables most peripheral clocks, Linux disables the ones
Why does U-Boot do that?
i.MX31 does that - the CPU, not U-Boot. I.e., this is the default power-on mode.
This is against U-Boot design guidelines which state that U-Boot shall only activate such peripherals that it uses itself.
didn't use I2C, the clock would stay disabled. And U-Boot on imx31_phycore uses an I2C EEPROM for environment data. So, after a reboot U-Boot would be
That's another area of bad design. Should we not change U-Boot such that it places the environment in flash?
Hm, no idea who and why decided to do that. I can only guess that this comes from the original BSPs somewhere, maybe they wanted to ship various EEPROM versions while keeping the same NOR, although both are probably hard-soldered on the CPU board (cannot recognise the eeprom, can be under the barcode label). And maybe they have some user-space tools of their own to access that EEPROM... no, not defending, just trying to guess what we might break if we switch.
BTW: What does "fir imx31_phycore to work after Linux reboot" mean? I cannot parse that.
Sorry, s/fir/fix/.
Thanks Guennadi --- Guennadi Liakhovetski, Ph.D.
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