It looks like the latest update to SDL has broken something. What was a normal SDL application is now a flickering mess - I think it's due to the newly-added sceGuSync in PSP_FlipHWSurface. Can someone verify?
--Edit: Sorry, it wasn't a problem in SDL after all! D'oh.
SDL problem
Until SDL waits on VBlank there might be some tearing in SDL apps. As a temporary solution I'd suggest waiting on vblank before a Flip or UpdateRects.
It is possible that moving sceGuSync to FlipHWSurface has caused an issue with certain combinations of screen updates ie: hw accelerated blits + anything else. Perhaps LockHWSurface also needs a sceGuSync (maybe it should lock the surface as well).
It is possible that moving sceGuSync to FlipHWSurface has caused an issue with certain combinations of screen updates ie: hw accelerated blits + anything else. Perhaps LockHWSurface also needs a sceGuSync (maybe it should lock the surface as well).