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 07:38:58 +0000
From:   Stanley Chang[昌育德] 
        <stanley_chang@...ltek.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
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

Hi Greg,

> > 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.

Okay, I will add this information at next version.

Thanks,
Stanley