On 02/10/2016 06:17 PM, Daniel Vetter wrote: > On Wed, Feb 10, 2016 at 5:28 PM, Mario Kleiner > <mario.kleiner.de at gmail.com> wrote: >> There's another scenario where this zero-ts case can be hit. If the driver >> drm_vblank_init()'s - setting all timestamps to zero - and then code starts >> using vblanks (drm_vblank_get()) without drm_vblank_on beforehand, which is >> afaics the case with nouveau. Unless that's considered an error as well, >> we'd need to init the timestamps to something non-zero but harmless like 1 >> usecs at drm_vblank_init() time? > > Both legacy modeset helpers and atomic ones assume by default that you > start out with everything disabled. Pre-atomic drivers make that > happen by calling disable_unused_functions() to shut down anything the > bios has enabled. I think this can't happen. > > For drivers that do take over bootloader display config they must call > vblank_on explicitly themselves, which i915 does. > >> What makes sense as output here? DRM_WARN_ONCE? > > I'd go with WARN_ON and tune it down if it's offensive. But WARN_ON > patch for 4.6 of course. > -Daniel >
Ok, so does this one have your R-b for stable as is? What about a proper nouveau fix if i find one? Probably also for 4.6 then, given that this patch fixes it up good enough for stable? -mario
