Application locks when sending few vertices at a time

[mardy]

Bug Report

This is a "funny" one. An application sending lots of glBegin()/glEnd() with very few vertices in them (say, just a triangle) ends up locking the Wii (on Doplhin this issue does not happen):

glBegin(GL_TRIANGLES);
glNormal3f(0.6983, -0.2564, -0.6683);
glVertex3f(0.0045, -0.001628, 8.2e-05);
glNormal3f(0.594, -0.4907, -0.6375);
glVertex3f(0.003717, -0.00307, 0.000116);
glNormal3f(0.364, -0.6469, -0.6701);
glVertex3f(0.002371, -0.004133, 9e-05);
glEnd();
glBegin(GL_TRIANGLES);
glNormal3f(0.364, -0.6469, -0.6701);
glVertex3f(0.002371, -0.004133, 9e-05);
glNormal3f(0.4056, 0.629, -0.6632);
glVertex3f(0.002408, 0.004109, 6.2e-05);
glNormal3f(0.6983, -0.2564, -0.6683);
glVertex3f(0.0045, -0.001628, 8.2e-05);
glEnd();

While debugging the issue, I noticed that adding aGX_DrawDone() in opengx near the end of glEnd() was making this issue go away, and then I verified that a ppcsync() call is good enough to fix the issue. On the application side, removing the useless glEnd() / glBegin() pairs also makes the issue disappear.

I believe this happens because the amount of the data sent into the pipe might be less than 32 bytes. It's as if the GX pipe is getting full without GX realizing it.

I'm not rushing to fix this bug, since working around it in the application is easy, and because it's not clear to me yet if the bug is in opengx or in libogc's GX API.