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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20130719235055.GB11498@kroah.com>
Date:	Fri, 19 Jul 2013 16:50:55 -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 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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/