Dear Steve Sakoman, In message <aanlkti==8qfve-r+nxvvcs4sjzmkv3-v1q2fxy4za...@mail.gmail.com> you wrote: > Beagle currently enables musb gadget support in u-boot in order to > support console communication over USB. > > The musb hardware remains in an active state as linux is launched.
Leaving USB enabled when starting an OS is calling for really serious trouble. > I've had complaints from those working on Linux power management -- it > seems that leaving things active prevents the kernel from entering > full chip retention. Power management is the least of your problems. I don't know for USB gadgets, but at least for Host Controllers you will suffer from (usually silent) memory corruption. > Is there an approved mechanism for shutting down hardware gracefully > prior to launching linux? > The console gadget seems somewhat of a special case since you really > want it to remain active till the very last moment so error messages > can be displayed. I think you should shut down USB with usb_stop(); (see common/cmd_bootm.c:643). Yes, even when this precents some error messages from being displayed on the USB console. [I never understood the hw designers that omitted a real serial port.] Eventually you might be looking at arch_preboot_os(), but actually is is NOT an architecture specific thing. 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: w...@denx.de In the pitiful, multipage, connection-boxed form to which the flow- chart has today been elaborated, it has proved to be useless as a design tool -- programmers draw flowcharts after, not before, writing the programs they describe. - Fred Brooks, Jr. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
