https://bugzilla.kernel.org/show_bug.cgi?id=75241
Bug ID: 75241 Summary: radeon_compute_pll_avivo broken in 3.15-rc3 Product: Drivers Version: 2.5 Kernel Version: 3.15-rc3 Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: high Priority: P1 Component: Video(DRI - non Intel) Assignee: drivers_video-dri@kernel-bugs.osdl.org Reporter: clemens@ladisch.de Regression: Yes
After upgrading from rc2 to rc3, my RS880 no longer outputs a signal that my monitor is able to show.
Bisected to this:
commit c2fb3094669a3205f16a32f4119d0afe40b1a1fd Author: Christian König christian.koenig@amd.com Date: Sun Apr 20 13:24:32 2014 +0200
drm/radeon: improve PLL limit handling in post div calculation
This improves the PLL parameters when we work at the limits of the allowed ranges.
Debug output with black screen:
kernel: [drm:drm_crtc_helper_set_config] attempting to set mode from userspace kernel: [drm:drm_mode_debug_printmodeline] Modeline 29:"1600x1200" 60 162000 1600 1664 1856 2160 1200 1201 1204 1250 0x48 0x5 kernel: [drm:radeon_encoder_set_active_device] setting active device to 00000200 from 00000200 00000200 for encoder 2 kernel: [drm:drm_crtc_helper_set_mode] [CRTC:14] kernel: [drm:radeon_atom_encoder_dpms] encoder dpms 21 to mode 3, devices 00000001, active_devices 00000000 kernel: [drm:radeon_compute_pll_avivo] 162000 - 161990, pll dividers - fb: 2036.3 ref: 30, post 6
With this commit reverted (and working screen):
kernel: [drm:radeon_compute_pll_avivo] 162000 - 16106, pll dividers - fb: 1023.5 ref: 13, post 7