From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roger Quadros Subject: Re: [PATCH v4 07/13] usb: otg: add OTG core Date: Tue, 8 Sep 2015 15:25:25 +0300 Message-ID: <55EED3B5.5030806@ti.com> References: <1440422484-4737-1-git-send-email-rogerq@ti.com> <1440422484-4737-8-git-send-email-rogerq@ti.com> <20150907012327.GG4914@shlinux2> <55ED6585.5050200@ti.com> <20150908083059.GD7802@shlinux2> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20150908083059.GD7802@shlinux2> Sender: linux-kernel-owner@vger.kernel.org To: Peter Chen Cc: stern@rowland.harvard.edu, balbi@ti.com, gregkh@linuxfoundation.org, dan.j.williams@intel.com, jun.li@freescale.com, mathias.nyman@linux.intel.com, tony@atomide.com, Joao.Pinto@synopsys.com, abrestic@chromium.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org List-Id: linux-omap@vger.kernel.org On 08/09/15 11:31, Peter Chen wrote: > On Mon, Sep 07, 2015 at 01:23:01PM +0300, Roger Quadros wrote: >> On 07/09/15 04:23, Peter Chen wrote: >>> On Mon, Aug 24, 2015 at 04:21:18PM +0300, Roger Quadros wrote: >>>> + * This is used by the USB Host stack to register the Host controller >>>> + * to the OTG core. Host controller must not be started by the >>>> + * caller as it is left upto the OTG state machine to do so. >>>> + * >>>> + * Returns: 0 on success, error value otherwise. >>>> + */ >>>> +int usb_otg_register_hcd(struct usb_hcd *hcd, unsigned int irqnum, >>>> + unsigned long irqflags, struct otg_hcd_ops *ops) >>>> +{ >>>> + struct usb_otg *otgd; >>>> + struct device *hcd_dev = hcd->self.controller; >>>> + struct device *otg_dev = usb_otg_get_device(hcd_dev); >>>> + >>> >>> One big problem here is: there are two designs for current (IP) driver >>> code, one creates dedicated hcd device as roothub's parent, like dwc3. >>> Another one doesn't do this, roothub's parent is core device (or otg device >>> in your patch), like chipidea and dwc2. >>> >>> Then, otg_dev will be glue layer device for chipidea after that. >> >> OK. Let's add a way for the otg controller driver to provide the host and gadget >> information to the otg core for such devices like chipidea and dwc2. >> > > Roger, not only chipidea and dwc2, I think the musb uses the same > hierarchy. If the host, device, and otg share the same register > region, host part can't be a platform driver since we don't want > to remap the same register region again. > > So, in the design, we may need to consider both situations, one > is otg/host/device has its own register region, and host is a > separate platform device (A), the other is three parts share the > same register region, there is only one platform driver (B). > > A: > > IP core device > | > | > |-----|-----| > gadget host platform device > | > roothub > > B: > > IP core device > | > | > |-----|-----| > gadget roothub > > >> This API must be called before the hcd/gadget-driver is added so that the otg >> core knows it's linked to an OTG controller. >> >> Any better idea? >> > > A flag stands for this hcd controller is the same with otg controller > can be used, this flag can be stored at struct usb_otg_config. What if there is another architecture like so? C: [Parent] | | |------------------|--------------| [OTG core] [gadget] [host] We need a more flexible mechanism to link the gadget and host device to the otg core for non DT case. How about adding struct usb_otg parameter to usb_otg_register_hcd()? e.g. int usb_otg_register_hcd(struct usb_otg *otg, struct usb_hcd *hcd, ..) If otg is NULL it will try DT otg-controller property or parent to get the otg controller. > > Peter > > P.S: I still read your code, I find not all APIs in this file are used > in your dwc3 example. Which ones? The ones for registering/unregistered host/gadget are used by hcd/udc core as part of usb_add/remove_hcd() and udc_bind_to_driver()/usb_gadget_remove_driver() cheers, -roger