On 11/05/16 16:54, Rob Herring wrote: > On Wed, May 04, 2016 at 04:47:18PM +0300, Roger Quadros wrote: >> On 04/05/16 16:17, Rob Herring wrote: >>> On Mon, May 02, 2016 at 03:18:53PM +0300, Roger Quadros wrote: >>>> From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx> >>>> >>>> Since some host controller (e.g. EHCI) needs a companion host controller >>>> (e.g. OHCI), this patch adds such a configuration to use it in the OTG >>>> core. >>>> >>>> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx> >>>> Signed-off-by: Roger Quadros <rogerq@xxxxxx> >>>> --- >>>> Documentation/devicetree/bindings/usb/generic.txt | 3 +++ >>>> drivers/usb/common/usb-otg.c | 32 ++++++++++++++++------- >>>> include/linux/usb/otg.h | 7 ++++- >>>> 3 files changed, 32 insertions(+), 10 deletions(-) >>>> >>>> diff --git a/Documentation/devicetree/bindings/usb/generic.txt b/Documentation/devicetree/bindings/usb/generic.txt >>>> index f6866c1..1db1c33 100644 >>>> --- a/Documentation/devicetree/bindings/usb/generic.txt >>>> +++ b/Documentation/devicetree/bindings/usb/generic.txt >>>> @@ -27,6 +27,9 @@ Optional properties: >>>> - otg-controller: phandle to otg controller. Host or gadget controllers can >>>> contain this property to link it to a particular OTG >>>> controller. >>>> + - hcd-needs-companion: must be present if otg controller is dealing with >>>> + EHCI host controller that needs a companion OHCI host >>>> + controller. >>> >>> Don't you need to have a link to the companion controller node? >> >> primary and companion controllers are totally independent of each other >> e.g. EHCI and OHCI. They are enabled by separate Kconfig options and >> the system can operate with either or both of them enabled. >> >> At the OTG layer we don't have information as to whether we should be waiting >> for both of them to register or not and hence need this "hcd-needs-companion" flag. > > What I mean is if you have 2 EHCI controllers with 2 companion > controllers, don't you need to know which companion goes with which EHCI > controller? Just like you do for the otg-controller property. > That is a very good point. I'm not very sure and it seems that current code won't work with multiple EHCI + companion instances. Alan, does USB core even know which EHCI and OHCI are linked to the same port or the handoff is software transparent? cheers, -roger -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
