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

[Mark Brown <broonie@kernel.org>]

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On Mon, Jan 12, 2015 at 10:05:49AM -0600, Rob Herring wrote:
> On Sun, Jan 11, 2015 at 10:29 AM, atull <atull@opensource.altera.com> wrote:

> > 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.

> That's not really true. Some WiFi devices have to load different
> firmware for client and AP modes and switching is a common usecase in
> phones.

Right, this is also very common for audio DSPs - the DSPs are frequently
much smaller than the total set of firmware they might want to run so
they need to switch at runtime.

> There may be other instances of drivers wanting configurable firmware
> names already. A common interface here would be nice. It could also be
> useful to expose the firmware names such that you could generate a
> list of all firmware files needed for a machine (that may already be
> possible with uevents?).

Some standard mechanism for enumerating the possible firmwares and
switching between them would definitely make life easier on the audio
side.  It'd also be good for userspace to be able to say it's got new
firmware to add to the list, but that's suggesting to me that the
enumeration part of things might be better handled in userspace.

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