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

From: Pavel Machek <pavel@denx.de>
To: Michal Simek <michal.simek@xilinx.com>
Cc: atull <atull@opensource.altera.com>,
	Pantelis Antoniou <pantelis.antoniou@konsulko.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	jgunthorpe@obsidianresearch.com, hpa@zytor.com,
	Michal Simek <monstr@monstr.eu>,
	rdunlap@infradead.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	devicetree@vger.kernel.org, robh+dt@kernel.org,
	Grant Likely <grant.likely@linaro.org>,
	iws@ovro.caltech.edu, linux-doc@vger.kernel.org,
	Mark Brown <broonie@kernel.org>,
	philip@balister.org, rubini@gnudd.com,
	Steffen Trumtrar <s.trumtrar@pengutronix.de>,
	jason@lakedaemon.net, kyle.teske@ni.com, nico@linaro.org,
	Felipe Balbi <balbi@ti.com>,
	m.chehab@samsung.com, davidb@codeaurora.org,
	Rob Landley <rob@landley.net>,
	davem@davemloft.net, cesarb@cesarb.net, sameo@linux.intel.com,
	akpm@linux-foundation.org,
	Linus Walleij <linus.walleij@linaro.org>,
	pawel.moll@arm.com, mark.rutland@arm.com,
	ijc+devicetree@hellion.org.uk, galak@codeaurora.org,
	devel@driverdev.osuosl.org,
	Alan Tull <delicious.quinoa@gmail.com>,
	dinguyen@opensource.altera.com, yvanderv@opensource.altera.com
Subject: Re: [PATCH v8 2/4] fpga manager: add sysfs interface document
Date: Tue, 13 Jan 2015 08:28:57 +0100	[thread overview]
Message-ID: <20150113072857.GA11760@amd> (raw)
In-Reply-To: <bed1d7ce1b984c79acc75a47495cb959@BL2FFO11FD043.protection.gbl>

Hi!

> >>>>>>>> +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.
...

> > What is cumbersome about symlink? Why is "fake" symlink in sysfs better?
> > 
> >> Previous uses of the firmware layer has been to use it to load once after
> >> bootup; this is different since some use cases will want to switch out
> >> the FPGA image.  If someone wants there to be only one FPGA image on
> >> the FGPA forever, they will probably not be using this framework; their
> >> FPGA will probably be loaded before Linux boots up.
> > 
> > Why? I have just one image on the fpga, and would prefer to load it
> > from Linux.
> 
> Pavel: These patches target staging and sysfs interface doesn't need to be stable
> at this time. I would prefer to add these patches to staging for 3.20
> and feel free to send the patch which fix this.

Interesting way to address patch review. "We'll merge it, and you can
fix it up later".

> With your code will be exactly clear how you want to use it and we can
> talk about it.

I'm pretty sure Alan knows what I want at this point, he just does not
want to do it.

For the record, I want to drop "firmware" file, use fixed firmware
name, and deal with multiple firmwares in userspace (using symlink or
udev magic).

I believe this is simplest solution, should be adequate, and is
certainly less ugly than implementing fake symlink in
/sys/.../firmware. And I have yet to hear what is wrong with that
suggestion.

Thanks,									
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
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