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

Pantelis Antoniou
2015-01-13T07:40:31Z

Hi Pavel,

> On Jan 13, 2015, at 09:28 , Pavel Machek <pavel@denx.de> wrote:
>
> 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).
>

That’s completely bogus. Using a fixed firmware file does not respond to
real world usage, and there are no words to describe the hacks using
symlinks and udev in an embedded product.

> 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.
>

Everything.

> Thanks,

Regards

— Pantelis

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