On Sun 2015-01-11 10:29:00, atull wrote: > On Sat, 10 Jan 2015, Pavel Machek wrote: > > > On Sat 2015-01-10 10:10:51, Pantelis Antoniou wrote: > > > Hi Pavel, > > > > > > > On Jan 9, 2015, at 22:56 , Pavel Machek <pavel@xxxxxxx> 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@xxxxxxxxxxxxxxxxxxxxx wrote: > > > >>>> + > > > >>>> +What: /sys/class/fpga_manager/<fpga>/firmware > > > >>>> +Date: October 2014 > > > >>>> +KernelVersion: 3.18 > > > >>>> +Contact: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx> > > > >>>> +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 > > Hi Pavel, > > I see that we could do it that way and it would eliminate one of the > sysfs files (../fpga_manager/<fpga>/firmware). Either way we are assuming > that there are fpga images in the filesystem in the firmware search path, > so I don't see why adding a piece of indirection (symlink) makes things > better. Well.. you are basically re-implementing symlink with ../fpga_manager/<fpga>/firmware "file" in sysfs, and doing it badly. It has no advantages over real symlink. > We want to be able to switch out the FPGA image > under control of userspace. So we don't want an interface that makes > it more cumbersome or tries to pretend that there's only one image. 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 -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
