On Mon, Oct 21, 2013 at 01:19:46PM +0200, Arokux X wrote: > Dear Kishon, > > thank you for the answer, no problem it was late! Your understanding > is almost correct. > > > From whatever I could understand, you have a USB HOST controller (each HOST > > controller has an EHCI controller and a companion OHCI controller?). There are > > separate clocks for each of EHCI and OHCI controller. EHCI and OHCI has > > separate PHYs. Both these PHYs are fed by the same common clock. And you have a > > separate reset bits for each of the PHYs. > > EHCI and OHCI have the same PHY. And this PHY has a reset bit. This is > exactly what bothers me. Because there should be something central to > both EHCI and OHCI which manages this reset bit, i.e. the bit should > be cleared if and only if both EHCI and OHCI controllers are unloaded > (as modules). I have done a nice picture of the hardware here, please > take a look at it: > > http://linux-sunxi.org/User:Arokux#USB_Host_Hardware > > I've just realized that there is another commo thing for EHCI and OHCI > - a GPIO which turns on the power to the USB_VBUS. The power should be > supplied if at least one of the EHCI or OHCI is loaded. This again > needs some central management. > > So to summarize, I have two things (reset bit and GPIO for the > USB_VBUS) which are common to EHCI and OHCI and need to be managed > outside of the EHCI/OHCI bus glue drivers. My exact question is: where > this management should be done? Are there good examples in the kernel > already? It looks to me like all of these are just different registers of the same controller. So to me, you should have a single driver for it, that manages both the reset, regulators and clocks, and loads both the ohci and ehci layers. bcma-hcd seems to be doing exactly that for example. Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com
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