Am Dienstag, den 13.09.2016, 17:59 -0700 schrieb Kevin Hilman: > Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx> writes: > > > On Tue, Sep 13, 2016 at 5:28 PM, Philipp Zabel <p.zabel@xxxxxxxxxxxxxx> wrote: > > [...] > > >>> I added Philipp and Hans to this thread - maybe they can comment on this. > >>> To sum it up, our problem is: > >>> - there are two separate USB PHYs on Meson GXBB > >>> - both are sharing the same reset line (provided by the reset-meson driver) > >>> - during initialization of the PHYs we must only call > >>> reset_control_reset(rstc) once (if we do it for the first *and* second > >>> PHY then the first PHY gets confused once the second PHY uses the > >>> reset because the first PHY's state is reset as well) > >> > >> If you have an initially asserted reset line and you can enable the > >> first module by deasserting the reset via reset_control_deassert (and > >> reset_control_assert to signal when the module may be disabled again > >> after use), shared resets are for you. > >> > >> If you need a reset pulse or have no direct control over the reset line, > >> (device_reset), the reset framework currently has no solution for this. > >> The ugly thing about reset_control_once would be that it can't re-reset > >> modules when unloading and reloading driver modules. > > > > The corresponding reset driver in question is reset-meson, which only > > implements reset (assert/deassert are not implemented). However, I > > don't know if this is due to hardware design. > > I think the hardware implements the latter, but maybe Neil can give > > more information here (I currently don't have access to my board so I > > cannot test how the hardware actually behaves). > > It's implemented that way because the hardware only supports a reset > pulse. Would it be possible to bring down both PHYs drivers, pull the reset line once, and then bring the drivers back up again? regards Philipp -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
