linux-kernel - Re: [PATCH v6 2/2] phy: rockchip-inno-usb2: add a new driver for Rockchip usb2phy

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Date:	Tue, 21 Jun 2016 11:05:14 +0200
From:	Heiko Stübner <heiko@...ech.de>
To:	Frank Wang <frank.wang@...k-chips.com>
Cc:	Guenter Roeck <linux@...ck-us.net>,
	Guenter Roeck <groeck@...gle.com>,
	Guenter Roeck <groeck@...omium.org>,
	Douglas Anderson <dianders@...omium.org>, jwerner@...omium.org,
	Kishon Vijay Abraham I <kishon@...com>, robh+dt@...nel.org,
	pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, Kumar Gala <galak@...eaurora.org>,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	linux-usb@...r.kernel.org, linux-rockchip@...ts.infradead.org,
	Ziyuan Xu <xzy.xu@...k-chips.com>,
	Kever Yang <kever.yang@...k-chips.com>,
	Tao Huang <huangtao@...k-chips.com>, william.wu@...k-chips.com
Subject: Re: [PATCH v6 2/2] phy: rockchip-inno-usb2: add a new driver for Rockchip usb2phy

Hi Frank,

Am Dienstag, 21. Juni 2016, 15:52:45 schrieb Frank Wang:
> On 2016/6/20 12:56, Guenter Roeck wrote:
> > On Sun, Jun 19, 2016 at 8:32 PM, Frank Wang <frank.wang@...k-chips.com> 
wrote:
> >>> Turns out my problem was one of terminology. Using "suspend" and
> >>> "resume" to me suggested the common use of suspend and resume
> >>> functions. That is not the case here. After mentally replacing
> >>> "suspend" with "power_off" and "resume" with "power_on", you are
> >>> right, no problem exists. Sorry for the noise.
> >>> 
> >>> Maybe it would be useful to replace "resume" with "power_on" and
> >>> "suspend" with "power_off" in the function and variable names to
> >>> reduce confusion and misunderstandings.
> >>> 
> >>> Thanks,
> >>> Guenter
> >> 
> >> Well, it does have a bits confusion, however, the phy-port always just
> >> goes
> >> to suspend and resume mode (Not power off and power on) in a fact. So
> >> must
> >> it be renamed?
> > 
> > Other phy drivers name the functions _power_off and _power_on and
> > avoid the confusion. The callbacks are named .power_off and .power_on,
> > which gives a clear indication of its intended purpose. Other drivers
> > implementing suspend/resume (such as the omap usb phy driver) tie
> > those functions not into the power_off/power_on callbacks, but into
> > the driver's suspend/resume callbacks. At least the omap driver has
> > separate power management functions.
> > 
> > Do the functions _have_ to be renamed ? Surely not. But, if the
> > functions are really suspend/resume functions and not
> > power_off/power_on functions, maybe they should tie to the
> > suspend/resume functions and not register themselves as
> > power_off/power_on functions ?
> 
> As Guenter mentioned above,  I doped out two solutions, one is that keep
> current process but renaming *_resume/*_suspend to
> *_power_on/*_power_off;

in a way, naming stuff "power_off", "power_on" actually matches. For one, the 
phy-block goes from unusable to usable by usb-devices and also will power-on a 
phy-supply regulator (often named vcc_host* on Rockchip boards) from the phy-
core.

> another is that do not assign power_on/power_off
> functions for phy_ops at phy creating time, then, shorten
> _SCHEDULE_DELAY_ delay time less that 10 Seconds, and the phy-port
> suspend/resume mechanism depend on _sm_work_ completely.

Which in turn would mean that we would always depend on a fully controllable 
phy block. Right now it seems, rk3036, rk3228, rk3368 (probably forgot some) 
have the same type of phy, but with at least the unplug-detection missing.
In its current form the driver can very well support those (later on) by 
simply working statically (only acting on phy_power callbacks and not going to 
suspend on its own).

Also having the work running in 10-second intervall seems wasteful.

> 
> So which is the better way from your view? or would you like to give
> other unique perceptions please?

As obvious from the above, I would prefer just renaming the functions :-)


Heiko