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SubjectRe: [PATCH v4 0/3] IR decoding using BPF
On Wed, May 23, 2018 at 02:21:27PM +0200, Daniel Borkmann wrote:
> On 05/18/2018 04:07 PM, Sean Young wrote:
> > The kernel IR decoders (drivers/media/rc/ir-*-decoder.c) support the most
> > widely used IR protocols, but there are many protocols which are not
> > supported[1]. For example, the lirc-remotes[2] repo has over 2700 remotes,
> > many of which are not supported by rc-core. There is a "long tail" of
> > unsupported IR protocols, for which lircd is need to decode the IR .
> >
> > IR encoding is done in such a way that some simple circuit can decode it;
> > therefore, bpf is ideal.
> >
> > In order to support all these protocols, here we have bpf based IR decoding.
> > The idea is that user-space can define a decoder in bpf, attach it to
> > the rc device through the lirc chardev.
> >
> > Separate work is underway to extend ir-keytable to have an extensive library
> > of bpf-based decoders, and a much expanded library of rc keymaps.
> >
> > Another future application would be to compile IRP[3] to a IR BPF program, and
> > so support virtually every remote without having to write a decoder for each.
> > It might also be possible to support non-button devices such as analog
> > directional pads or air conditioning remote controls and decode the target
> > temperature in bpf, and pass that to an input device.
>
> Mauro, are you fine with this series going via bpf-next? How ugly would this
> get with regards to merge conflicts wrt drivers/media/rc/?

There are no merge conflict and as of yet, I'm not expecting any. If anything
I suspect the bpf tree is more likely to change, so merging via bpf-next
might make more sense.

Thanks

Sean

>
> Thanks,
> Daniel
>
> > Thanks,
> >
> > Sean Young
> >
> > [1] http://www.hifi-remote.com/wiki/index.php?title=DecodeIR
> > [2] https://sourceforge.net/p/lirc-remotes/code/ci/master/tree/remotes/
> > [3] http://www.hifi-remote.com/wiki/index.php?title=IRP_Notation
> >
> > Changes since v3:
> > - Implemented review comments from Quentin Monnet and Y Song (thanks!)
> > - More helpful and better formatted bpf helper documentation
> > - Changed back to bpf_prog_array rather than open-coded implementation
> > - scancodes can be 64 bit
> > - bpf gets passed values in microseconds, not nanoseconds.
> > microseconds is more than than enough (IR receivers support carriers upto
> > 70kHz, at which point a single period is already 14 microseconds). Also,
> > this makes it much more consistent with lirc mode2.
> > - Since it looks much more like lirc mode2, rename the program type to
> > BPF_PROG_TYPE_LIRC_MODE2.
> > - Rebased on bpf-next
> >
> > Changes since v2:
> > - Fixed locking issues
> > - Improved self-test to cover more cases
> > - Rebased on bpf-next again
> >
> > Changes since v1:
> > - Code review comments from Y Song <ys114321@gmail.com> and
> > Randy Dunlap <rdunlap@infradead.org>
> > - Re-wrote sample bpf to be selftest
> > - Renamed RAWIR_DECODER -> RAWIR_EVENT (Kconfig, context, bpf prog type)
> > - Rebase on bpf-next
> > - Introduced bpf_rawir_event context structure with simpler access checking
> >
> > Sean Young (3):
> > bpf: bpf_prog_array_copy() should return -ENOENT if exclude_prog not
> > found
> > media: rc: introduce BPF_PROG_LIRC_MODE2
> > bpf: add selftest for lirc_mode2 type program
> >
> > drivers/media/rc/Kconfig | 13 +
> > drivers/media/rc/Makefile | 1 +
> > drivers/media/rc/bpf-lirc.c | 308 ++++++++++++++++++
> > drivers/media/rc/lirc_dev.c | 30 ++
> > drivers/media/rc/rc-core-priv.h | 22 ++
> > drivers/media/rc/rc-ir-raw.c | 12 +-
> > include/linux/bpf_rcdev.h | 30 ++
> > include/linux/bpf_types.h | 3 +
> > include/uapi/linux/bpf.h | 53 ++-
> > kernel/bpf/core.c | 11 +-
> > kernel/bpf/syscall.c | 7 +
> > kernel/trace/bpf_trace.c | 2 +
> > tools/bpf/bpftool/prog.c | 1 +
> > tools/include/uapi/linux/bpf.h | 53 ++-
> > tools/include/uapi/linux/lirc.h | 217 ++++++++++++
> > tools/lib/bpf/libbpf.c | 1 +
> > tools/testing/selftests/bpf/Makefile | 8 +-
> > tools/testing/selftests/bpf/bpf_helpers.h | 6 +
> > .../testing/selftests/bpf/test_lirc_mode2.sh | 28 ++
> > .../selftests/bpf/test_lirc_mode2_kern.c | 23 ++
> > .../selftests/bpf/test_lirc_mode2_user.c | 154 +++++++++
> > 21 files changed, 974 insertions(+), 9 deletions(-)
> > create mode 100644 drivers/media/rc/bpf-lirc.c
> > create mode 100644 include/linux/bpf_rcdev.h
> > create mode 100644 tools/include/uapi/linux/lirc.h
> > create mode 100755 tools/testing/selftests/bpf/test_lirc_mode2.sh
> > create mode 100644 tools/testing/selftests/bpf/test_lirc_mode2_kern.c
> > create mode 100644 tools/testing/selftests/bpf/test_lirc_mode2_user.c
> >

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