On Fri, 16 Apr 2021 20:30:05 +0200, Daniel Vetter wrote: > > On Fri, Apr 16, 2021 at 2:53 PM Takashi Iwai <tiwai@xxxxxxx> wrote: > > > > Currently the DRM fbcon helper for console blank, > > drm_fb_helper_blank(), simply calls drm_fb_helper_dpms() and always > > returns zero, supposing the driver dealing with DPMS or atomic > > crtc->active flip to handle blanking the screen. It works on most of > > devices, but broken on most of KVM/QEMU graphics: bochs, qxl and > > cirrus drivers just ignore crtc->active state change as blanking (or > > cirrus ignoring DPMS). In practice, when you run like > > % setterm --blank force > > on a VT console, the screen freezes without actually blanking. > > > > A simple fix for this problem would be not to rely on DPMS but let > > fbcon performs the generic blank code. This can be achieved just by > > returning an error from drm_fb_helper_blank(). > > > > In this patch, we add a flag, no_dpms_blank, to drm_fb_helper for > > indicating that the driver doesn't handle blank via DPMS or > > crtc->active flip. When this flag is set, drm_fb_helper_blank() > > simply returns an error, so that fbcon falls back to its generic blank > > handler. The flag is set to both bochs and qxl drivers in this patch, > > while cirrus is left untouched as it's declared as to-be-deprecated. > > > > Link: https://lore.kernel.org/dri-devel/20170726205636.19144-1-tiwai@xxxxxxx/ > > BugLink: https://bugzilla.suse.com/show_bug.cgi?id=1095700 > > Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> > > Uh we're supposed to fix these drivers to actually blank (scan out > black, worst case), not paper over it in higher levels. Atomic kms is > meant to be a somewhat useful abstraction. So now fbcon blanks, but > your desktop still just freezes. > > > --- > > > > Here I whip a dead horse again, revisiting the long-standing issue > > stated in the previous patch set in 2017: > > https://lore.kernel.org/dri-devel/20170726205636.19144-1-tiwai@xxxxxxx/ > > > > I thought to refresh the previous patch set at first, but it seems > > invalid for the atomic modeset case. And for the atomic, it's even > > more difficult to propagate the return from the bottom to up. > > So I ended up with this approach as it's much simpler. > > Yeah that's because atomic assume you can at least blank your screen to black. OK, then there is no other way than fixing those drivers to deal with the blanking... I cooked up an experimental patch for bochs, and will submit later. thanks, Takashi _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
