Mauro Carvalho Chehab wrote:
Pekka Sarnila wrote:
The problem using vendor class is that there is no standard. Each vendor
can define its own way using endpoints (and has done so e.g Logitech
joysticks). Thus each usb ir receiver must have its own specific driver.
However then you get the raw ir codes. When using HID class, generic
HID driver can do the job. But then you get HID key codes directly not
ir codes.
We started writing an abstraction layer for IR, using the input. The idea
is to allow the IR receivers to work with different IR's, as several users
prefer to use universal IR's to control their devices, instead of the original
one. This is already used by all V4L drivers and I intend to port most of
the DVB drivers to use it as well soon.
This is very good.
The problem here is that at least afatech ir receiver has the ir code to
key code build in, so trough HID you can use only the remote whose ir to
key translate table has been loaded to the aftech device. Unless that
can be easily controlled by the user HID is no good for this.
Also this should not be seen at all as dvb question. First, not all the
world uses dvb standard (including USA) but uses very similar tv-sticks
with identical ir receivers and remotes.
Despiste its name, the DVB subsystem is not specific for DVB standards, but
it is meant to be used by all DTV standards (and almost all DTV standards
are already supported).
But most of the world still uses analog (they can not afford yet the
transfer). Those tv-sticks have identical receivers. And there are usb
ir receivers not embedded to tv-sticks. Conceptually and technically it
has nothing to do with any tv or any other audiovisual system system
(e.g. a remote controlled weather station).
So dvb is both as a place and a name misleading.
Second there are many other
type of usb devices with ir receiver. So dvb layer should not be
involved at all. There maybe would be need for hid-ir-remote layer (your
code suggestion moved there). However even there IMHO better would be
just to improve HID <-> input layer interface so that input layer could
divert the remotes input to generic remotes layer instead of keyboard
layer. IMHO this would be the real linux way.
This is already happening.
See drivers/media/IR on linux-next for the IR common code. The ir-core is
provided by ir-keytable.c and ir-sysfs.c, and it is not DVB or V4L specific.
Well I was talking about HID remotes that don't give ir codes but key
codes. What to do with them?
The ir-common module were developed for V4L drivers and will probably be
changed into a more generic way, with the integration with lirc.
However linux usb layer has been build so that it was technically
impossible to put it there without completely redesigning usb <-> higher
layer (including HID) interface. But I'm of the opinion that that
redesign should be done anyway.
Feel free to submit patches. My plan is to integrate the DVB devices soon
Yes, I have thought of it. But it is a big job, I'm quite busy, and
after all mostly the benefit is more esthetical than practical. A lot of
other usb strandard and vendor class interrupt endpoint drivers beside
HID should be rewritten. Writing new ones would be easier though.
into the new ir-core. I should start with dvb-usb-remote, where most of the
DVB USB devices use to attach their IR's. Unfortunately, af9015 doesn't
rely on the dvb-usb-remote, so, it will require some specific changes.
As I don't have any af9015 device, I'll likely postpone it or wait for
someone to do the job.
Well that was the original point of my involvement. It can support both
the dvb-usb-remote and HID. The problem with af9015/dvb-usb-remote is
that it uses usb vendor class endpoint (all trough I have used 'vendor
class' to specifically mean usb vendor class). Usb vendor classes have
no standard. But af9015 can also use USB HID class (remote as keyboard)
in a standard manner. That would avoid using special device based driver.
Now the question is, how much all usb based ir receivers have in common,
and how much they differ. This should determine on what level and in
which way they should be handled. How much and on what level there
should be common code and where device specific driver code would be
needed and where and how the ir-to-code translate should take place.
There are several different ways for IR receivers, and, at least for
vendor class, no standard way to handle. They can use GPIO polling,
they can use i2c layer, they can use IRQ (on PCI devices) and the data
may be provided in parallel or on a serial interface.
Well the thing is that even with usb each device can have non standard
user vendor endpoint. In case of af9015 it can provide the ir code.
The idea of the ir-core is to provide support for all those options.
Even for those that do provide key codes trough standard HID layer
instead of ir codes trough specific device drivers?
IMHO all that have HID endpoint that works (either as such or with some
generic quirk) should be handled by HID first and then conveyed to
generic remotes layer that handles all remote controllers what ever the
lower layers (and does translate per remote not per ir receiver). Vendor
class should be avoided unless that's the only way to make it work
right. But using HID is not without problems either.
Almost all chipsets only provide IR via vendor class. I agree that using
standard HID class is the better way for doing it.
Yes, but look below.
Now with the two receivers that need the quirk. If they don't have
vendor class bulk endpoint for reading ir codes, then specific driver is
out anyway. However then changes to HID driver would be needed to make
the translate work. The quirk just makes them work as generic usb
keyboard with no remote specific translate. With afatech, driver loads
the translate table to the device, different for different remotes. I
don't know if one table could handle them all. Maybe this table should
be loaded from a user space file. Nor do I know how it is with other
receivers: can the table be loaded or is it fixed. In any case a generic
secondary per remote user configurable translate would be highly
desirable. And I don't mean lircd. This job is IMHO kernel level job and
lircd won't work here anyway. It does ir code to key code or function
translate not key code to key code translate. How nice it would be if
there would be a generic usb ir receiver class that all vendors used.
There seems to be no way to make this well and clean.
The ir-core provides standard ways to replace the IR keycode and IR protocols.
The IR protocol change is already working with vendor class with em28xx driver.
The thing is that remote controller trough HID layer does not provide IR
keycode but standard keyboard key code. And HID layer does not know that
it is a remote controller but sees it as an ordinary usb keyboard. The
question is that how can it tell the upper layer that it really is a
remote controller so that the event would end up to generic ir-core.
Pekka
Cheers,
Mauro
--
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
