Philip, On Mon, Oct 24, 2016 at 11:00:05AM +0200, Philipp Zabel wrote: > Hi Iztok, Moritz, > > Am Freitag, den 21.10.2016, 10:04 -0700 schrieb Moritz Fischer: > > Iztok, > > > > On Fri, Oct 21, 2016 at 03:08:47AM -0700, [email protected] wrote: > > > Hi Moritz, > > > > > > I was looking at your reset implementation for Zynq: > > > https://github.com/Xilinx/linux-xlnx/blob/629041605b93343ad2e8971ceaac3edcef0b043b/drivers/reset/reset-zynq.c > > > I went through related mailing list posts (including earlier versions of > > > the patch) so I kind of understand what to change in the device tree. > > > > Please look at the upstream kernel sources and use the mailing list > > (lkml) if you want to report bugs. Xilinx' vendor tree might or might > > not be up to date. > > > > > I would like to use this driver to reset the Zynq I2C controller, since > > > we have trouble with it getting into a lock up state. > > > I plan to use function device_reset_optional() from: > > > https://github.com/Xilinx/linux-xlnx/blob/629041605b93343ad2e8971ceaac3edcef0b043b/include/linux/reset.h > > > > > > But this function is calling the reset function pointer from the > > > reset_control_ops structure. > > > For the zynq driver this function pointer is not defined, only assert, > > > deassert and status are. > > > > > > Is this a missing implementation, or is there a default implementation (I > > > did not find one) which which performs an assert+deassert, > > > or is there another set of reset APIs I should use inside the kernel. > > > > You could just call reset_control_assert() and reset_control_deassert(). > > You're right there is currently no implementation for the 'reset' function > > for > > zynq (and most of the other SoCs). I'll need to see if it makes sense at > > all. > > The implementation of reset_control_reset in software really only makes > sense if the reset provider driver knows about the necessary delays for > all reset consumers.
That's what I meant by needing to see if it makes sense at all; it makes no sense to have a 'reset' if you don't know how long it needs to be asserted for, since that's obviously a consumer property. Thanks for clarifying, Moritz
