Re: [RFC PATCH v2 0/1] FPGA subsystem core

["H. Peter Anvin" <hpa@zytor.com>]

On 10/04/2013 10:44 AM, Michal Simek wrote:
> 
> If you look at it in general I believe that there is wide range of 
> applications which just contain one bitstream per fpga and the 
> bitstream is replaced by newer version in upgrade. For them 
> firmware interface should be pretty useful. Just setup firmware 
> name with bitstream and it will be automatically loaded in startup 
> phase.
> 
> Then there is another set of applications especially in connection 
> to partial reconfiguration where this can be done statically by 
> pregenerated partial bitstreams or automatically generated on 
> target cpu. For doing everything on the target firmware interface 
> is not the best because everything can be handled by user 
> application and it is easier just to push this bitstream to do 
> device and not to save it to the fs.
> 
> I think the question here is if this subsystem could have several 
> interfaces. For example Alan is asking for adding char support. 
> Does it even make sense to have more interfaces with the same 
> backend driver? When this is answered then we can talk which one 
> make sense to have. In v2 is sysfs and firmware one. Adding char
> is also easy to do.
> 

Greg, what do you think?

I agree that the firmware interface makes sense when the use of the
FPGA is an implementation detail in a fixed hardware configuration,
but that is a fairly restricted use case all things considered.

	-hpa