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    SubjectRe: bit errors on spitz
    Andy Green wrote: 
    > On 03/11/10 15:42, Somebody in the thread at some point said:
    > > Andy Green wrote:
    > >
    > >> I saw very similar failures for a long time on our iMX31 based device.
    > >> Eventually I found a Freescale errata where the RAM inside the USB2
    > >> macrocell started to make single bit errors below 1.38V Vcore; ours was
    > >> 1.4V at that time but dipped on CPU load.
    > >
    > > Good tip. It seems that nobody ported driver for the voltage control
    > > chip ISL6271 from 2.4 kernel, and bootloader probably does not set
    > > correct values.

    > Unless there's more to it in the way the zaurus using it that regulator
    > isn't programmable digitally.

    OOPS, I made a mistake and linked ISL6721 instead of ISL6271 there.
    Now it is fixed:

    This one has I2C. It is connected to GPIO 3 (PWR_SCL) and GPIO 4

    It is visible between the black plastic and the large circular coil:

    > Reading about your CF Card WLAN related issues they suck down a good
    > amount of power when their radio is up, I would definitely suggest
    > monitoring with a 'scope the various rails (Vcore, RAM and whatever it
    > is the CF Card is powered by) while putting it under load.

    I guess that Zaurus has a good power design and that voltage should be
    constant enough. CF has a dedicated step down (plus 2.8V power detector
    (Why so low, if CF standard requres more?)), HDD has a dedicated step
    up/down. USB has dedicated step up. Companion chips use dedicated 3.3V
    step down. Audio uses dedicated linear regulator. CPU has several
    dedicated step downs, CPU 3.3V uses step-up to 5V and then down to 3.3V
    (which is shared only with IOPORT).

    Nearest common point between CF card power and CPU power is the battery.


    Stanislav Brabec

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