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

Pavel Machek
2015-01-13T07:29:05Z

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
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