On Wed, Dec 02, 2009 at 10:44:58AM -0200, Mauro Carvalho Chehab wrote: > Dmitry Torokhov wrote: > > On Tue, Dec 01, 2009 at 07:05:49PM -0200, Mauro Carvalho Chehab wrote: > >> Dmitry Torokhov wrote: > >>> On Tue, Dec 01, 2009 at 05:00:40PM -0200, Mauro Carvalho Chehab wrote: > >>>> Dmitry Torokhov wrote: > >>>>> On Tue, Dec 01, 2009 at 03:29:44PM -0200, Mauro Carvalho Chehab wrote: > >>>>>> For sure we need to add an EVIOSETPROTO ioctl to allow the driver > >>>>>> to change the protocol in runtime. > >>>>>> > >>>>> Mauro, > >>>>> > >>>>> I think this kind of confuguration belongs to lirc device space, > >>>>> not input/evdev. This is the same as protocol selection for psmouse > >>>>> module: while it is normally auto-detected we have sysfs attribute to > >>>>> force one or another and it is tied to serio device, not input > >>>>> device. > >>>> Dmitry, > >>>> > >>>> This has nothing to do with the raw interface nor with lirc. This problem > >>>> happens with the evdev interface and already affects the in-kernel drivers. > >>>> > >>>> In this case, psmouse is not a good example. With a mouse, when a movement > >>>> occurs, you'll receive some data from its port. So, a software can autodetect > >>>> the protocol. The same principle can be used also with a raw pulse/space > >>>> interface, where software can autodetect the protocol. > >>> Or, in certain cases, it can not. > >>> > >>> [... skipped rationale for adding a way to control protocol (with which > >>> I agree) ...] > >>> > >>>> To solve this, we really need to extend evdev API to do 3 things: enumberate the > >>>> supported protocols, get the current protocol(s), and select the protocol(s) that > >>>> will be used by a newer table. > >>>> > >>> And here we start disagreeing. My preference would be for adding this > >>> API on lirc device level (i.e. /syc/class/lirc/lircX/blah namespace), > >>> since it only applicable to IR, not to input devices in general. > >>> > >>> Once you selected proper protocol(s) and maybe instantiated several > >>> input devices then udev (by examining input device capabilities and > >>> optionally looking up at the parent device properties) would use > >>> input evdev API to load proper keymap. Because translation of > >>> driver-specific codes into standard key definitions is in the input > >>> realm. Reading these driver-specific codes from hardware is outside of > >>> input layer domain. > >>> > >>> Just as psmouse ability to specify protocol is not shoved into evdev; > >>> just as atkbd quirks (force release key list and other driver-specific > >>> options) are not in evdev either; we should not overload evdev interface > >>> with IR-specific items. > >> I'm not against mapping those features as sysfs atributes, but they don't belong > >> to lirc, as far as I understand. From all we've discussed, we'll create a lirc > >> interface to allow the direct usage of raw IO. However, IR protocol is a property > >> that is not related to raw IO mode but, instead, to evdev mode. > >> > > > > Why would protocol relate to evdev node? Evdev does not really care what > > how the fact that a certain button was pressed was communicated to it. > > It may be deliveretd through PS/2 port, or maybe it was Bluetooth HID, > > or USB HID or USB boot protocol or some custom protocol, or RC-5, NEC or > > some custom IR protocol. It makes no difference _whatsoever_ to evdev > > nor any users of evdev care about protocol used by underlying hardware > > device to transmit the data. > > > >> We might add a /sys/class/IR and add IR specific stuff there, but it seems > >> overkill to me and will hide the fact that those parameters are part of the evdev > >> interface. > >> > >> So, I would just add the IR sysfs parameters at the /sys/class/input, if > >> the device is an IR (or create it is /sys/class/input/IR). > >> > >> I agree that the code to implement the IR specific sysfs parameter should be kept > >> oustide input core, as they're specific to IR implementations. > >> > >> Would this work for you? > > > > I am seeing a little bit differently structured subsystem for IR at the > > moment. I think we should do something like this: > > > > - receivers create /sys/class/lirc devices. These devices provide API > > with a ring buffer (fifo) for the raw data stream coming from (and to) > > them. > > The raw interface applies only to the devices that doesn't have a hardware decoder > (something between 40%-60% of the currently supported devices). 50% is quite a number I think. But if driver does not allow access to the raw stream - it will refuse binding to lirc_dev interface. > > > - we allow registering several data interfaces/decoders that can be bound > > (manually or maybe automatically) to lirc devices. lirc devices may > > provide hints as to which interface(s) better suited for handling the > > data coming form particular receiver. Several interfaces may be bound > > to one device at a time. > > - one of the interfaces is interface implementing current lirc_dev > > - other interfaces may be in-kernel RC-5 decoder or other decoders. > > decoders will create instances of input devices > > I don't see why having more than one interface, especially for devices with > hardware decoders. > > On IR remote receivers, internally, there's just one interface per hardware. > > Considering the hardware decoding case, why to artificially create other > interfaces that can't be used simultaneously? No current hardware > decoders can do that (or, at least, no current implementation allows). > We're foreseen some cases where we'll have that (like Patrick's dib0700 driver), > but for now, it is not possible to offer more than one interface to userspace. > Creating an arbitrary number of artificial interfaces just to pass a parameter > to the driver (the protocol), really seems overkill to me. We need to cater to the future cases as well. I don't want to redesign it in 2 years. But for devices that have only hardware decoders I suppose we can short-curcuit "interfaces" and have a library-like module creating input devices directly. > > In the case of the cheap devices with just raw interfaces, running in-kernel > decoders, while it will work if you create one interface per protocol > per IR receiver, this also seems overkill. Why to do that? It sounds that it will > just create additional complexity at the kernelspace and at the userspace, since > now userspace programs will need to open more than one device to receive the > keycodes. _Yes_!!! You open as many event devices as there are devices you are interested in receiving data from. Multiplexing devices are bad, bad, bad. Witness /dev/input/mouse and all the attempts at working around the fact that if you have a special driver for one of your devices you receive events from the same device through 2 interfaces and all kind of "grab", "super-grab", "smart-grab" schemes are born. > > > (for each remote/substream that they can recognize). > > I'm assuming that, by remote, you're referring to a remote receiver (and not to > the remote itself), right? If we could separate by remote transmitter that would be the best I think, but I understand that it is rarely possible? -- 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
