linux-kernel - Re: [RFC PATCH v2 08/15] usb:cdns3: Implements device operations part of the API

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Date:   Fri, 14 Dec 2018 09:34:21 +0800
From:   Peter Chen <hzpeterchen@...il.com>
To:     pawell@...ence.com
Cc:     nsekhar@...com, rogerq@...com, devicetree@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>,
        adouglas@...ence.com, jbergsagel@...com, nm@...com,
        sureshp@...ence.com, peter.chen@....com, pjez@...ence.com,
        kurahul@...ence.com, balbi@...nel.org
Subject: Re: [RFC PATCH v2 08/15] usb:cdns3: Implements device operations part
 of the API

On Wed, Dec 12, 2018 at 3:49 AM Pawel Laszczak <pawell@...ence.com> wrote:
>
> Hi,
>
> >On 10/12/18 7:42 AM, Peter Chen wrote:
> >>>> +static struct usb_ep *cdns3_gadget_match_ep(struct usb_gadget *gadget,
> >>>> +                                         struct usb_endpoint_descriptor *desc,
> >>>> +                                         struct usb_ss_ep_comp_descriptor *comp_desc)
> >>>> +{
> >>>> +     struct cdns3_device *priv_dev = gadget_to_cdns3_device(gadget);
> >>>> +     struct cdns3_endpoint *priv_ep;
> >>>> +     unsigned long flags;
> >>>> +
> >>>> +     priv_ep = cdns3_find_available_ss_ep(priv_dev, desc);
> >>>> +     if (IS_ERR(priv_ep)) {
> >>>> +             dev_err(&priv_dev->dev, "no available ep\n");
> >>>> +             return NULL;
> >>>> +     }
> >>>> +
> >>>> +     dev_dbg(&priv_dev->dev, "match endpoint: %s\n", priv_ep->name);
> >>>> +
> >>>> +     spin_lock_irqsave(&priv_dev->lock, flags);
> >>>> +     priv_ep->endpoint.desc = desc;
> >>>> +     priv_ep->dir  = usb_endpoint_dir_in(desc) ? USB_DIR_IN : USB_DIR_OUT;
> >>>> +     priv_ep->type = usb_endpoint_type(desc);
> >>>> +
> >>>> +     list_add_tail(&priv_ep->ep_match_pending_list,
> >>>> +                   &priv_dev->ep_match_list);
> >>>> +     spin_unlock_irqrestore(&priv_dev->lock, flags);
> >>>> +     return &priv_ep->endpoint;
> >>>> +}
> >>> Why do you need a custom match_ep?
> >>> doesn't usb_ep_autoconfig suffice?
> >>>
> >>> You can check if EP is claimed or not by checking the ep->claimed flag.
> >>>
> >> It is a special requirement for this IP, the EP type and MaxPacketSize
> >> changing can't be done at runtime, eg, at ep->enable. See below commit
> >> for detail.
> >>
> >>     usb: cdns3: gadget: configure all endpoints before set configuration
> >>
> >>     Cadence IP has one limitation that all endpoints must be configured
> >>     (Type & MaxPacketSize) before setting configuration through hardware
> >>     register, it means we can't change endpoints configuration after
> >>     set_configuration.
> >>
> >>     In this patch, we add non-control endpoint through usb_ss->ep_match_list,
> >>     which is added when the gadget driver uses usb_ep_autoconfig to configure
> >>     specific endpoint; When the udc driver receives set_configurion request,
> >>     it goes through usb_ss->ep_match_list, and configure all endpoints
> >>     accordingly.
> >>
> >>     At usb_ep_ops.enable/disable, we only enable and disable endpoint through
> >>     ep_cfg register which can be changed after set_configuration, and do
> >>     some software operation accordingly.
> >
> >All this should be part of comments in code along with information about
> >controller versions which suffer from the errata.
> >
> >Is there a version of controller available which does not have the
> >defect? Is there a future plan to fix this?
> >
> >If any of that is yes, you probably want to handle this with runtime
> >detection of version (like done with DWC3_REVISION_XXX macros).
> >Sometimes the hardware-read versions themselves are incorrect, so its
> >better to introduce a version specific compatible too like
> >"cdns,usb-1.0.0" (as hinted to by Rob Herring as well).
> >
>
> custom match_ep is used and works with all versions of the gen1
> controller. Future (gen2) releases of the controller won’t have such
> limitation but there is no plan to change current (gen1) functionality
> of the controller.
>
> I will add comment before cdns3_gadget_match_ep function.
> Also I will change cdns,usb3 to cdns,usb3-1.0.0 and add additional
> cdns,usb3-1.0.1 compatible.
>
> cdns,usb3-1.0.1 will be for current version of controller which I use.
> cdns,usb3-1.0.0 will be for older version - Peter Chan platform.
> I now that I have some changes in controller, and one of them require
> some changes in DRD driver. It will be safer to add two separate
> version in compatibles.
>

Pawel, could we have correct register to show controller version? It is
better we could version judgement at runtime instead of static compatible.

Peter