Hi Michel, thanks for responding.
> Basically you're comparing apples (TearFree, the amdgpu/radeon driver > changes above) and oranges (DRI page flipping, the modesetting change > above). > > DRI page flipping is an old mechanism (supported by the amdgpu/radeon > drivers as well, "forever", since long before TearFree) for direct > scanout from buffers whose contents were produced with direct rendering > by the client. Because it scans out directly, output transformations > such as rotation are traditionally not supported with DRI page flipping. > I see. So I have to double buffer the rotated buffer and flip it on vsync. According to this discussion https://bugs.freedesktop.org/show_bug.cgi?id=32789 it should be able to double-buffer the rotated frontbuffer and let a 'damage' trigger rendering to the offscreen buffer and wait for vsync to flip. Right? > TearFree uses separate dedicated scanout buffers, to which the "main" > buffer contents are copied on demand. > > Originally, these three things (DRI page flipping, rotation and > TearFree) were separate and mutually exclusive. However, the > amdgpu/radeon drivers support all of them the same time these days; this > still requires an extra copy in some cases, but that could be eliminated > at least in the non-rotated DRI page flipping case. > > https://gitlab.freedesktop.org/xorg/xserver/merge_requests/24 has the > start of TearFree support for the modesetting driver, but it's still > mutually exclusive with rotation (DRI3 page flipping should work with > TearFree, but may still exhibit tearing if the client/user disables > sync-to-vblank). Couldn't we extend modesetting in addition to Martin's TearFree patch the same way you did here for Radeon?: https://cgit.freedesktop.org/xorg/driver/xf86-video-ati/commit/?id=798c4fd16d339b1ad5fd729cc884be084c60e38b Best regards -Carsten
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