After upgrading my MythTV machine to Debian Bullseye and MythTV 31, my Streamzap remote control stopped working correctly: the up and down buttons were working, but the OK button wasn't.

Here's the complete solution that made it work with the built-in kernel support (i.e. without LIRC).

Button re-mapping

Since some of the buttons were working, but not others, I figured that the buttons were probably not mapped to the right keys.

Inspired by these old v4l-utils-based instructions, I made my own custom keymap by by copying the original keymap:

cp /lib/udev/rc_keymaps/streamzap.toml /etc/rc_keymaps/

and then modifying it to adapt it to what MythTV needs. This is what I ended up with:

<span class="createlink"><a href="/blog.cgi?do=create&amp;from=posts%2Fusing-streamzap-remote-with-mythtv-debian-bullseye&amp;page=protocols" rel="nofollow">?</a>protocols</span>
name = "streamzap"
protocol = "rc-5-sz"
0x28c0 = "KEY_0"
0x28c1 = "KEY_1"
0x28c2 = "KEY_2"
0x28c3 = "KEY_3"
0x28c4 = "KEY_4"
0x28c5 = "KEY_5"
0x28c6 = "KEY_6"
0x28c7 = "KEY_7"
0x28c8 = "KEY_8"
0x28c9 = "KEY_9"
0x28ca = "KEY_ESC"
0x28cb = "KEY_MUTE"
0x28cc = "KEY_UP"
0x28ce = "KEY_DOWN"
0x28cf = "KEY_LEFTBRACE"
0x28d0 = "KEY_UP"
0x28d1 = "KEY_LEFT"
0x28d2 = "KEY_ENTER"
0x28d3 = "KEY_RIGHT"
0x28d4 = "KEY_DOWN"
0x28d5 = "KEY_M"
0x28d6 = "KEY_ESC"
0x28d7 = "KEY_L"
0x28d8 = "KEY_P"
0x28d9 = "KEY_ESC"
0x28da = "KEY_BACK"
0x28db = "KEY_FORWARD"
0x28dc = "KEY_R"
0x28dd = "KEY_PAGEUP"
0x28de = "KEY_PAGEDOWN"
0x28e0 = "KEY_D"
0x28e1 = "KEY_I"
0x28e2 = "KEY_END"
0x28e3 = "KEY_A"

Note that the keycodes can be found in the kernel source code.

With my own keymap in place at /etc/rc_keymaps/streamzap.toml, I changed /etc/rc_maps.cfg to have the kernel driver automatically use it:

--- a/rc_maps.cfg
+++ b/rc_maps.cfg
@@ -126,7 +126,7 @@
 *      rc-real-audio-220-32-keys real_audio_220_32_keys.toml
 *      rc-reddo                 reddo.toml
 *      rc-snapstream-firefly    snapstream_firefly.toml
-*      rc-streamzap             streamzap.toml
+*      rc-streamzap             /etc/rc_keymaps/streamzap.toml
 *      rc-su3000                su3000.toml
 *      rc-tango                 tango.toml
 *      rc-tanix-tx3mini         tanix_tx3mini.toml

Button repeat delay

To adjust the delay before button presses are repeated, I followed these old out-of-date instructions on the MythTV wiki and put the following in /etc/udev/rules.d/streamzap.rules:

ACTION=="add", ATTRS{idVendor}=="0e9c", ATTRS{idProduct}=="0000", RUN+="/usr/bin/ir-keytable -s rc0 -D 1000 -P 250"

Note that the -d option has been replaced with -s in the latest version of ir-keytable.

To check that the Streamzap is indeed detected as rc0 on your system, use this command:

$ ir-keytable 
Found /sys/class/rc/rc0/ with:
    Name: Streamzap PC Remote Infrared Receiver (0e9c:0000)
    Driver: streamzap
    Default keymap: rc-streamzap

Make sure you don't pass the -c to ir-keytable or else it will clear the keymap set via /etc/rc_maps.cfg, removing all of the button mappings.