Hi all
-----Ursprüngliche Nachricht----- Von: Heiko Schocher [mailto:hs@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