On Tue, Dec 08, 2009 at 09:58:53AM -0200, Mauro Carvalho Chehab wrote: > Dmitry Torokhov wrote: > > On Mon, Dec 07, 2009 at 09:44:14PM -0200, Mauro Carvalho Chehab wrote: > > >>> What about capabilities of the receiver, what frequencies? > >>> If a receiver has multiple frequencies, how do you report what > >>> frequency the data came in on? > >> IMO, via sysfs. > > > > We probably need to think what exactly we report through sysfs siunce it > > is ABI of sorts. > > Yes, sure. > > Probably, the exact needs will popup only when we start to actually writing that > part of the core. > > My intention for now is to just create a /sys/class/irrcv, with one node > per each IR receiver and adding a protocol enumeration/selection node > there, and add some capabilities for the in-kernel decoders and lirc_dev > to create new nodes under that class. > > When the decoders/lirc_dev patches popup, we'll need to review those sysfs > API's. > > >>> What about multiple apps simultaneously using the pulse data? > >> IMO, the better is to limit the raw interface to just one open. > >> > > > > Why woudl we want to do this? Quite often there is a need for "observer" > > that maybe does not act on data but allows capturing it. Single-user > > inetrfaces are PITA. > > That should work fine as well, but I'm not sure how we'll detect overrun with > several kfifo readers. > Push the data into readers so they can do te decoding at their own pace. Some can do it in interrupt context, some will need workqueue/thread. They can also regilate the depth of the buffer, according to their needs. > >>> How big is the receive queue? > >> It should be big enough to receive at least one keycode event. Considering that > >> the driver will use kfifo (IMO, it is a good strategy, especially since you > >> won't need any lock if just one open is allowed), it will require a power of two size. > >> > > > > Would not it be wither driver- or protocol-specific? > > Probably. > > > > >>> How does access work, root only or any user? > >> IMO, it should be the same requirement as used by an input interface. > >> > >>> How are capabilities exposed, sysfs, etc? > >> IMO, sysfs. > >> > >>> What is the interface for attaching an in-kernel decoder? > >> IMO, it should use the kfifo for it. However, if we allow both raw data and > >> in-kernel decoders to read data there, we'll need a spinlock to protect the > >> kfifo. > >> > > > > I think Jon meant userspace interface for attaching particular decoder. > > I don't think we need an userspace interface for the in-kernel decoders. All > it needs is to enable/disable the protocol decoders, imo via sysfs interface. > > >>> If there is an in-kernel decoder should the pulse data stop being > >>> reported, partially stopped, something else? > >> I don't have a strong opinion here, but, from the previous discussions, it > >> seems that people want it to be double-reported by default. If so, I think > >> we need to implement a command at the raw interface to allow disabling the > >> in-kernel decoder, while the raw interface is kept open. > > > > Why don't you simply let consumers decide where they will get their data? > > How? > You end up with N evdev devices. Let application (MythTV) say "I want to use /dev/input/event1" (well, it will need persistent udev rule, but that's a detail). Another application will chose another event node. User can decide she'd rather use lircd - and so configire applications to use event5. Any maybe turned off the in-kernel decoders if they are of no use and there is a concern that they consume too mcuh resoures. Won't this work? -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
