On 01/22/2016 04:18 PM, Ville Syrjälä wrote: > On Fri, Jan 22, 2016 at 12:06:00PM +0900, Michel Dänzer wrote: >> >> [ Trimming KDE folks from Cc ] >> >> On 21.01.2016 19:09, Daniel Vetter wrote: >>> On Thu, Jan 21, 2016 at 05:36:46PM +0900, Michel Dänzer wrote: >>>> On 21.01.2016 16:58, Daniel Vetter wrote: >>>>> >>>>> Can you please point me at the vblank on/off jump bug please? >>>> >>>> AFAIR I originally reported it in response to >>>> http://lists.freedesktop.org/archives/dri-devel/2015-August/087841.html >>>> , but I can't find that in the archives, so maybe that was just on IRC. >>>> See >>>> http://lists.freedesktop.org/archives/dri-devel/2016-January/099122.html >>>> . Basically, I ran into the bug fixed by your patch because the counter >>>> jumped forward on every DPMS off, so it hit the 32-bit boundary after >>>> just a few days. >>> >>> Ok, so just uncovered the overflow bug. >> >> Not sure what you mean by "just", but to be clear: The drm_vblank_on/off >> counter jumping bug (similar to the bug this thread is about), which >> exposed the overflow bug, is still alive and kicking in 4.5. It seems >> to happen when turning off the CRTC: >> >> [drm:drm_update_vblank_count] updating vblank count on crtc 0: >> current=218104694, diff=0, hw=916 hw_last=916 >> [drm:radeon_get_vblank_counter_kms] crtc 0: dist from vblank start 3 >> [drm:drm_calc_vbltimestamp_from_scanoutpos] crtc 0 : v 0x7 p(2199,-45)@ >> 7304.307354 -> 7304.308006 [e 0 us, 0 rep] >> [drm:radeon_get_vblank_counter_kms] crtc 0: dist from vblank start 3 >> [drm:drm_update_vblank_count] updating vblank count on crtc 0: >> current=218104694, diff=16776301, hw=1 hw_last=916 > > Not sure what bug we're talking about here, but here the hw counter > clearly jumps backwards. > >> [drm:radeon_get_vblank_counter_kms] Query failed! stat 3 >> [drm:radeon_get_vblank_counter_kms] Query failed! stat 3 >> [drm:drm_update_vblank_count] updating vblank count on crtc 1: current=0, >> diff=0, hw=0 hw_last=0 >> [drm:radeon_get_vblank_counter_kms] Query failed! stat 3 >> [drm:radeon_get_vblank_counter_kms] Query failed! stat 3 >> [drm:drm_update_vblank_count] updating vblank count on crtc 2: current=0, >> diff=0, hw=0 hw_last=0 >> [drm:radeon_get_vblank_counter_kms] Query failed! stat 3 >> [drm:radeon_get_vblank_counter_kms] Query failed! stat 3 >> [drm:drm_update_vblank_count] updating vblank count on crtc 3: current=0, >> diff=0, hw=0 hw_last=0 >> [drm:radeon_get_vblank_counter_kms] Query failed! stat 1 >> [drm:drm_calc_vbltimestamp_from_scanoutpos] crtc 0 : v 0x1 p(0,0)@ >> 7304.317140 -> 7304.317140 [e 0 us, 0 rep] >> [drm:radeon_get_vblank_counter_kms] Query failed! stat 1 >> [drm:drm_update_vblank_count] updating vblank count on crtc 0: >> current=234880995, diff=16777215, hw=0 hw_last=1 > > Same here. > > These things just don't happen on i915 because drm_vblank_off() and > drm_vblank_on() are always called around the times when the hw counter > might get reset. Or at least that's how it should be. >
Fwiw, testing the HD-57570 single display with my patch that uses drm_vblank_off/on() in the DPMS OFF/ON path of radeon-kms does show hardware counter reset to zero as expected, but no jumps of software vblank counter. So with that vblank_off/on placement it seems to work nicely here. -mario >> dev->max_vblank_count = 0xffffffff, which makes the wraparound code in >> drm_update_vblank_count a no-op. Maybe you can reproduce it if you >> artificially set a lower max_vblank_count in the driver. >> >> >> -- >> Earthling Michel Dänzer | http://www.amd.com >> Libre software enthusiast | Mesa and X developer >
