Date: Fri, 19 Jul 2013 16:50:55 -0700
From: Greg KH <gregkh@linuxfoundation.org>
To: Kishon Vijay Abraham I <kishon@ti.com>
Cc: kyungmin.park@samsung.com, balbi@ti.com, jg1.han@samsung.com,
        s.nawrocki@samsung.com, kgene.kim@samsung.com, grant.likely@linaro.org,
        tony@atomide.com, arnd@arndb.de, swarren@nvidia.com,
        devicetree-discuss@lists.ozlabs.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-samsung-soc@vger.kernel.org, linux-omap@vger.kernel.org,
        linux-usb@vger.kernel.org, linux-media@vger.kernel.org,
        linux-fbdev@vger.kernel.org, akpm@linux-foundation.org,
        balajitk@ti.com, george.cherian@ti.com, nsekhar@ti.com
Subject: Re: [PATCH 01/15] drivers: phy: add generic PHY framework
Message-ID: <20130719235055.GB11498@kroah.com>
References: <1374129984-765-1-git-send-email-kishon@ti.com>
 <1374129984-765-2-git-send-email-kishon@ti.com>
 <20130718072004.GA16720@kroah.com>
 <51E7AE88.3050007@ti.com>
 <20130718154954.GA31961@kroah.com>
 <51E8D086.809@ti.com>
 <20130719054311.GA14638@kroah.com>
 <51E8D4E0.8060200@ti.com>
 <20130719062941.GA23611@kroah.com>
 <51E8DE51.1060404@ti.com>
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On Fri, Jul 19, 2013 at 12:06:01PM +0530, Kishon Vijay Abraham I wrote:
> Hi,
> 
> On Friday 19 July 2013 11:59 AM, Greg KH wrote:
> > On Fri, Jul 19, 2013 at 11:25:44AM +0530, Kishon Vijay Abraham I wrote:
> >> Hi,
> >>
> >> On Friday 19 July 2013 11:13 AM, Greg KH wrote:
> >>> On Fri, Jul 19, 2013 at 11:07:10AM +0530, Kishon Vijay Abraham I wrote:
> >>>>>>>> +	ret = dev_set_name(&phy->dev, "%s.%d", dev_name(dev), id);
> >>>>>>>
> >>>>>>> Your naming is odd, no "phy" anywhere in it?  You rely on the sender to
> >>>>>>> never send a duplicate name.id pair?  Why not create your own ids based
> >>>>>>> on the number of phys in the system, like almost all other classes and
> >>>>>>> subsystems do?
> >>>>>>
> >>>>>> hmm.. some PHY drivers use the id they provide to perform some of their
> >>>>>> internal operation as in [1] (This is used only if a single PHY provider
> >>>>>> implements multiple PHYS). Probably I'll add an option like PLATFORM_DEVID_AUTO
> >>>>>> to give the PHY drivers an option to use auto id.
> >>>>>>
> >>>>>> [1] ->
> >>>>>> http://archive.arm.linux.org.uk/lurker/message/20130628.134308.4a8f7668.ca.html
> >>>>>
> >>>>> No, who cares about the id?  No one outside of the phy core ever should,
> >>>>> because you pass back the only pointer that they really do care about,
> >>>>> if they need to do anything with the device.  Use that, and then you can
> >>>>
> >>>> hmm.. ok.
> >>>>
> >>>>> rip out all of the "search for a phy by a string" logic, as that's not
> >>>>
> >>>> Actually this is needed for non-dt boot case. In the case of dt boot, we use a
> >>>> phandle by which the controller can get a reference to the phy. But in the case
> >>>> of non-dt boot, the controller can get a reference to the phy only by label.
> >>>
> >>> I don't understand.  They registered the phy, and got back a pointer to
> >>> it.  Why can't they save it in their local structure to use it again
> >>> later if needed?  They should never have to "ask" for the device, as the
> >>
> >> One is a *PHY provider* driver which is a driver for some PHY device. This will
> >> use phy_create to create the phy.
> >> The other is a *PHY consumer* driver which might be any controller driver (can
> >> be USB/SATA/PCIE). The PHY consumer will use phy_get to get a reference to the
> >> phy (by *phandle* in the case of dt boot and *label* in the case of non-dt boot).
> >>> device id might be unknown if there are multiple devices in the system.
> >>
> >> I agree with you on the device id part. That need not be known to the PHY driver.
> > 
> > How does a consumer know which "label" to use in a non-dt system if
> > there are multiple PHYs in the system?
> 
> That should be passed using platform data.

Ick, don't pass strings around, pass pointers.  If you have platform
data you can get to, then put the pointer there, don't use a "name".

thanks,

greg k-h
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