On Fri, Aug 24, 2018 at 05:18:02PM -0300, Fabio Estevam wrote: > Hi Michael, > > On Fri, Aug 24, 2018 at 4:55 PM, Michael Grzeschik wrote: > > > I get that it is not safe to toggle bits if the clock is not > > there. We could check for the bootsource. Is it possible to > > ensure that we are started by imx-usb-loader? > > It is possible to determine if we have started via USB download mode. > > Check the is_boot_from_usb() implementation in U-Boot for a reference. Right, So it seems to be safe to reach for the phys registers on mx6. On mx5 and similar we have a nop phy and the only way to communicate with it is through usbmisc, which is also in the register space that leads to a hang if one clock is missing. I will search for another solutions on those SoCs. mgr -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |