[Bug 97260] [bisected] R9 290 low performance in Linux 4.7

https://bugs.freedesktop.org/show_bug.cgi?id=97260

--- Comment #16 from Alex Deucher alexdeucher@gmail.com --- Does just reverting this chunk fix the issue?

@@ -1630,6 +1631,9 @@ int radeon_modeset_init(struct radeon_device *rdev)

rdev->ddev->mode_config.funcs = &radeon_mode_funcs;

+ if (radeon_use_pflipirq == 2 && rdev->family >= CHIP_R600) + rdev->ddev->mode_config.async_page_flip = true; + if (ASIC_IS_DCE5(rdev)) { rdev->ddev->mode_config.max_width = 16384; rdev->ddev->mode_config.max_height = 16384;