linux-kernel - Re: [PATCH v2 1/3] usb: phy: add usb phy notify port status API

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Date:   Tue, 30 May 2023 08:32:40 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Stanley Chang[昌育德] 
        <stanley_chang@...ltek.com>
Cc:     Vinod Koul <vkoul@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Michael Grzeschik <m.grzeschik@...gutronix.de>,
        Bagas Sanjaya <bagasdotme@...il.com>,
        Flavio Suligoi <f.suligoi@...m.it>,
        Matthias Kaehlcke <mka@...omium.org>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Ray Chi <raychi@...gle.com>,
        "linux-phy@...ts.infradead.org" <linux-phy@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] usb: phy: add usb phy notify port status API

On Tue, May 30, 2023 at 02:19:45AM +0000, Stanley Chang[昌育德] wrote:
> Hi Greg,
> 
> > > --- a/include/linux/usb/phy.h
> > > +++ b/include/linux/usb/phy.h
> > > @@ -144,6 +144,10 @@ struct usb_phy {
> > >        */
> > >       int     (*set_wakeup)(struct usb_phy *x, bool enabled);
> > >
> > > +     /* notify phy port status change */
> > > +     int     (*notify_port_status)(struct usb_phy *x,
> > > +             int port, u16 portstatus, u16 portchange);
> > > +
> > >       /* notify phy connect status change */
> > >       int     (*notify_connect)(struct usb_phy *x,
> > >                       enum usb_device_speed speed);
> > 
> > Why can't this be part of the same notify_connect() callback?
> 
> The notify connect is at device ready. But I want notify port status change before port reset.
> 
> > What makes it different somehow?  Please document this much better.
> 
> In Realtek phy driver, we have designed to dynamically adjust disconnection level and calibrate phy parameters.
> So we do this when the device connected bit changes and when the disconnected bit changes.
> Port status change notification:
> 1. Check if portstatus is USB_PORT_STAT_CONNECTION and portchange is USB_PORT_STAT_C_CONNECTION.
>   The device is connected, the driver lowers the disconnection level and calibrates the phy parameters.
> 2. The device disconnects, the driver increases the disconnect level and calibrates the phy parameters.
> 
> If we adjust the disconnection level in notify_connect , the disconnect may have been triggered at this stage. 
> So we need to change that as early as possible.

Please put this type of information in the changelog and in the comments
for the callback when you resubmit it.

thanks,

greg k-h