linux-kernel - Re: [PATCH 01/15] drivers: phy: add generic PHY framework

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Message-ID: <20130719062941.GA23611@kroah.com>
Date:	Thu, 18 Jul 2013 23:29:41 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Kishon Vijay Abraham I <kishon@...com>
Cc:	kyungmin.park@...sung.com, balbi@...com, jg1.han@...sung.com,
	s.nawrocki@...sung.com, kgene.kim@...sung.com,
	grant.likely@...aro.org, tony@...mide.com, arnd@...db.de,
	swarren@...dia.com, devicetree-discuss@...ts.ozlabs.org,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, linux-omap@...r.kernel.org,
	linux-usb@...r.kernel.org, linux-media@...r.kernel.org,
	linux-fbdev@...r.kernel.org, akpm@...ux-foundation.org,
	balajitk@...com, george.cherian@...com, nsekhar@...com
Subject: Re: [PATCH 01/15] drivers: phy: add generic PHY framework

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?

Do you have any drivers that are non-dt using this yet?

greg k-h
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