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: http://www.penguin.cz/~utx/zaurus/datasheets/power/XScale/ISL6271A.pdf This one has I2C. It is connected to GPIO 3 (PWR_SCL) and GPIO 4 (PWR_SDA). It is visible between the black plastic and the large circular coil: http://www.penguin.cz/~utx/zaurus/teardown#pcbt > 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 http://www.penguin.cz/~utx/zaurus _______________________________________________ Zaurus-devel mailing list Zaurus-devel@lists.linuxtogo.org http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/zaurus-devel
