On Fri, 2013-10-04 at 16:33 -0700, Greg Kroah-Hartman wrote: > On Fri, Oct 04, 2013 at 11:12:13AM -0700, H. Peter Anvin wrote: > > 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. > > Ideally I thought this would be just like "firmware", you dump the file > to the FPGA, it validates it and away you go with a new image running in > the chip. > > But, it sounds like this is much more complicated, so much so that > configfs might be the correct interface for it, as you can do lots of > things there, and it is very flexible (some say too flexible...) > > A char device, with a zillion different custom ioctls is also a way to > do it, but one that I really want to avoid as that gets messy really > quickly. Hi Greg, We are discussing a char device that has very few interfaces: - a way of writing the image to fpga - a way of getting fpga manager status - a way of setting fpga manager state This all looks like standard char driver interface to me. Writing the image could be writing to the devnode (cat image.bin > /dev/fpga0). The status stuff would be sysfs attributes. All normal stuff any char driver in the kernel would do. Why not just go with that? > > thanks, > > greg k-h > -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
