linux-kernel - Re: [PATCH 0/7] Add USB remote wakeup driver

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Date:   Thu, 21 Dec 2017 14:48:24 +0800
From:   Chunfeng Yun <chunfeng.yun@...iatek.com>
To:     Rob Herring <robh@...nel.org>
CC:     Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        "Mark Rutland" <mark.rutland@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Jean Delvare <jdelvare@...e.de>,
        "Sean Wang" <sean.wang@...iatek.com>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH 0/7] Add USB remote wakeup driver

On Fri, 2017-12-15 at 14:55 -0600, Rob Herring wrote:
> On Sat, Dec 09, 2017 at 04:45:29PM +0800, Chunfeng Yun wrote:
> >     These patches introduce the SSUSB and SPM glue layer driver which is
> > used to support usb remote wakeup. Usually the glue layer is put into
> > a system controller, such as PERICFG module.
> >     The old way to support usb wakeup is put into SSUSB controller drivers,
> > including xhci-mtk driver and mtu3 driver, but there are some problems:
> >     1. can't disdinguish the relation between glue layer and SSUSB IP
> >        when SoCs supports multi SSUSB IPs;
> >     2. duplicated code for wakeup are put into both xhci-mtk and mtu3
> >        drivers;
> >     3. the glue layer may vary on different SoCs with SSUSB IP, and will
> >        make SSUSB controller drivers complicated;
> >     In order to resolve these problems, it's useful to make the glue layer
> > transparent by extracting a seperated driver, meanwhile to reduce the
> > duplicated code and simplify SSUSB controller drivers.
> 
> Both the driver and binding look overly complicated to me when it looks 
> like you just have 2 versions of enable/disable functions which modify 
> a single register. The complexity may be justified if this was a common 
> binding and driver, but it is not.
> 
> You already have a phandle to the system controller. Can't you add cells 
> to it to handle any differences between instances? That and SoC specific 
> compatible strings should be enough to handle differences.
Yes, adding cells will also work well, I'll try it, thanks a lot
> 
> Rob