On 1 February 2017 at 11:21, Michel Dänzer <[email protected]> wrote: > On 01/02/17 04:05 AM, David Airlie wrote: >>> From: "Michel Dänzer" <[email protected]> >>> On 26/01/17 07:13 PM, Qiang Yu wrote: >>>> >>>> @@ -145,7 +157,7 @@ present_check_flip(RRCrtcPtr crtc, >>>> return FALSE; >>>> >>>> /* Fail to flip if we have slave outputs */ >>>> - if (screen->output_slaves) >>>> + if (screen->output_slaves && >>>> present_check_output_slaves_active(screen)) >>>> return FALSE; >>>> >>>> /* Make sure the window hasn't been redirected with Composite */ >>>> >>> >>> Actually, I'm not sure why we need to check for slave outputs here at >>> all. Dave, did you run into an actual problem without the check, or was >>> it just a theoretical concern? The commit log says: >> >> You don't get an output on USB without the fix. > > Hmm, why not? Flipping just replaces the screen pixmap's storage; > copying from the screen pixmap to the shared pixmap should still work > fine, and flips generate the damage needed to trigger it as well.
Hmm maybe it wasn't USB, it was reverse prime. I can't recall the exact brokenness, I'd have to set up a reverse prime test box and remove the line. I don't think it was as simple as the damage getting lost. Dave. _______________________________________________ [email protected]: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: https://lists.x.org/mailman/listinfo/xorg-devel
