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

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Date:   Fri, 15 Dec 2017 14:55:04 -0600
From:   Rob Herring <robh@...nel.org>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>
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 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.

Rob