Valentin Longchamp wrote: > From what I > read in this post, the USB block used in i.MX31 is very similar to the one > used in MPC834x family. Could someone confirm this and quickly explain the > differences in the USB blocks ?
The USB blocks in the 8349 and mx31 are basically the same, with some minor exceptions. The 8349 has one host controller with two ports plus a dual-role (OTG) controller. The mx31 has two host controllers (one port each), plus an OTG controller. The 8349 has some additional snooping registers not needed on mx31. > Since MPC834x USB module seems to be already quite well advanced, I would be > happy to try to port the work which was done for i.MX31 in order to help > i.MX31 mainline support, or at least help me to have a functionnal USB > support on our i.MX31 hardware. This is exactly what I'm working on. > Now I have a more precise question about the actual implementation of > Freescale i.MX31 kernel release (here is the patch: > http://bitshrine.org/gpp/linux-2.6.16-mx31-usb-2.patch). It works well, but > only with low-current devices (I have tested the ehci support with USB > pendrive flash disk). But when I try to plug in some higher current consumers > like a wifi pendrive for instance, which needs 300 mA, the configuration is > rejected ... [snip] > Now I was not able to find in the code where this limit is fixed for my ehci > hardware. Because I haven't found a current limitation in the USB block or > transceiver (Phillips ISP1504) documentation (quick look). The limitation exists in the MIC2536 power switches used on the mx31ads board, which provide only 150mA per port. This is reflected in the 'power_budget' fields of the platform_data structs found in arch/arm/mach-mx3/usb.c, and passed to the generic ehci code (as Alan points out) in drivers/usb/host/ehci-arc.c: hcd->power_budget = config->power_budget; > Thank you for your help. You're welcome. > Valentin Longchamp Regards, --duck ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
