Re: [PATCH v8 2/4] fpga manager: add sysfs interface document

From: Pavel Machek <pavel@denx.de>
To: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Cc: mark.rutland@arm.com, linux-doc@vger.kernel.org,
	rubini@gnudd.com, hpa@zytor.com,
	Steffen Trumtrar <s.trumtrar@pengutronix.de>,
	devel@driverdev.osuosl.org, sameo@linux.intel.com,
	nico@linaro.org, ijc+devicetree@hellion.org.uk,
	Michal Simek <michal.simek@xilinx.com>,
	kyle.teske@ni.com, jgunthorpe@obsidianresearch.com,
	Grant Likely <grant.likely@linaro.org>,
	davidb@codeaurora.org, Linus Walleij <linus.walleij@linaro.org>,
	cesarb@cesarb.net, devicetree@vger.kernel.org,
	jason@lakedaemon.net, pawel.moll@arm.com, iws@ovro.caltech.edu,
	atull <atull@opensource.altera.com>,
	Mark Brown <broonie@kernel.org>,
	philip@balister.org, dinguyen@opensource.altera.com,
	Michal Simek <monstr@monstr.eu>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	yvanderv@opensource.altera.com,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Felipe Balbi <balbi@ti.com>, Alan Tull <delicious.qu>
Subject: Re: [PATCH v8 2/4] fpga manager: add sysfs interface document
Date: Sat, 10 Jan 2015 16:11:18 +0100	[thread overview]
Message-ID: <20150110151118.GA16036@amd> (raw)
In-Reply-To: <4D4EA2D5-68DD-49F7-9E2D-3A0A8F6AF9CA@konsulko.com>

On Sat 2015-01-10 10:10:51, Pantelis Antoniou wrote:
> Hi Pavel,
> 
> > On Jan 9, 2015, at 22:56 , Pavel Machek <pavel@denx.de> wrote:
> > 
> > On Fri 2015-01-09 13:14:24, atull wrote:
> >> On Wed, 7 Jan 2015, Pavel Machek wrote:
> >> 
> >>> On Tue 2015-01-06 14:13:37, atull@opensource.altera.com wrote:
> >>>> +
> >>>> +What:		/sys/class/fpga_manager/<fpga>/firmware
> >>>> +Date:		October 2014
> >>>> +KernelVersion:	3.18
> >>>> +Contact:	Alan Tull <atull@opensource.altera.com>
> >>>> +Description:	Name of the FPGA image file to load using firmware
> >>>> class.
> >>> 
> >>> This one is ugly: it unneccessarily passes firmware name through the
> >>> kernel. Just make interface and code simpler by always passing
> >>> "socfpga-fpga-image" or something like that.
> >>> 
> >>> Thanks,
> >>> 									Pavel
> >> 
> >> Hi Pavel,
> >> 
> >> It might be ugly.  It's not unnecessary.  Some uses of FPGAs involve
> >> switching out the FPGA images dynamically under control of the userspace.
> > 
> > Then configure udev to load right firmware for you, or ln -s
> > image-i-want-now socfpga-fpga-image to select the one to read…?
> > 
> 
> Who said that udev is going to be available in the kind of system this is going to end in?

Noone.

> Doing ln -s tricks to load a different image? Really?

But if you don't have udev, you can do ln -s. It is better than
open-coding symlink functionality into
/sys/class/fpga_manager/<fpga>/firmware ... cause that's what this is.

Actually, clean implementation of "firmware" would be symlink in
sysfs; but I'd say that would be overdoing it.

> I say the interface is fine as it is.

I say it is not.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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