Hi all > -----Ursprüngliche Nachricht----- > Von: Heiko Schocher [mailto:h...@denx.de] > Gesendet: Dienstag, 9. September 2014 16:22 > An: Lukasz Majewski > Cc: u-boot@lists.denx.de; Tom Rini; Marek Vasut; Liu Bin; Stockmann, Lukas > Betreff: Re: [PATCH v1 0/2] usb: dfu: am335x: allow dfu in fullspeed mode > only > > Hello Lukasz, > > Am 09.09.2014 15:43, schrieb Lukasz Majewski: > > Hi Heiko, > > > >> This patchserie adds the new config option CONFIG_DFU_FULLSPEED. > > > > Is there any special reason to support Full Speed (12 Mbit/sec - USB > > 1.1) and not rely solely on the High Speed (USB 2.0) as we do now? > > > >> If this is enabled DFU uses fullspeed only. This is used on the > >> siemens boards. > > > > Is there any DFU problem with the mentioned Siemens board, that we > > must use USB 1.1? > > > > I'd also appreciate more verbose rationale for this patch series - why > > this change is needed? What is the expected improvement? > > They have a "USB HW protection circuit" and therefore they only allowed to > use fullspeed ... > > @Lukas Stockman: Maybe you could answer this better than me?
Yes, it's because of a protection circuit. Our device is 24V AC powered, if someone uses a non galvanically isolated transformer and misswires it, it could burn down the USB host. That's why we have a protection on the USB side which limits the speed to 12Mbit/sec. Regards, Lukas _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
