Controller recognition Intermittently fails with Retro-Bit controllers

[jerellsworth]

I'm still doing research on this, but I wanted to go ahead and start an issue in case there's any previous work on it (I couldn't find any other mentions on the internet).

I've found that, in some situations, no button inputs from Retro-Bit 6-button controllers are detected. Sometimes power cycling the MD fixes it, but usually not. I presume that something about these controllers is out-of-spec in a way that JOY_init, in particular, is vulnerable to.

What I've found:

• Problem occurs with several different instances/colors of this product: https://www.amazon.com/Retro-Bit-Official-Genesis-Controller-6-Button-Arcade/dp/B07NXX77V1?ref_=ast_sto_dp&th=1
• The problem does not occur for commercial games.
• The controller works when wired through a Team Player.
• Games affected do not explicitly invoke any joypad initialization code and rely on SGDK defaults.
• Games work fine in several emulators and with OEM 3-button pad.
• Tested with SGDK 1.90 (Sorry it's not most recent, but I don't think joypad stuff changed in 2.00).
• Tested on a USA OEM Model 2.
• Tested loading via Mega Everdrive X5 and Pro.

You might assert that these controllers aren't supported, which is fair enough, but they are extremely common and prominent on Amazon so it would be nice if they worked.

I'll post more as a do further research. Let me know what I can do to help. I appreciate all the work y'all do on this project.

[jerellsworth]

I wrote a minimal test rom to check what was happening https://github.com/jerellsworth/joytest. After initializing, the port that the controller is in registers as PORT_TYPE_UNKNOWN and the joypad as JOY_TYPE_UNKNOWN.