On Tue, Aug 21, 2012 at 2:40 AM, Dave Airlie <airlied@xxxxxxxxxx> wrote: > So we've had a fair few reports of fbcon handover breakage between > efi/vesafb and i915 surface recently, so I dedicated a couple of > days to finding the problem. > > Essentially the last thing we saw was the conflicting framebuffer > message and that was all. > > So after much tracing with direct netconsole writes (printks > under console_lock not so useful), I think I found the race. > > Thread A (driver load) Thread B (timer thread) > unbind_con_driver -> | > bind_con_driver -> | > vc->vc_sw->con_deinit -> | > fbcon_deinit -> | > console_lock() | > | | > | fbcon_flashcursor timer fires > | console_lock() <- blocked for A > | > | > fbcon_del_cursor_timer -> > del_timer_sync > (BOOM) > > Of course because all of this is under the console lock, > we never see anything, also since we also just unbound the active > console guess what we never see anything. > > Hopefully this fixes the problem for anyone seeing vesafb->kms > driver handoff. > > Signed-off-by: David Airlie <airlied@xxxxxxxxxx> > --- > drivers/video/console/fbcon.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c > index 2e471c2..f8a79fc 100644 > --- a/drivers/video/console/fbcon.c > +++ b/drivers/video/console/fbcon.c > @@ -372,8 +372,12 @@ static void fb_flashcursor(struct work_struct *work) > struct vc_data *vc = NULL; > int c; > int mode; > + int ret; > + > + ret = console_trylock(); > + if (ret == 0) > + return; > > - console_lock(); > if (ops && ops->currcon != -1) > vc = vc_cons[ops->currcon].d; > I have a Dell XPS 8300 machine with a Radeon card in it that started showing this problem yesterday with 3.6-rc2 kernels. I tested this patch on top of v3.6-rc2-206-g10c63c9 this morning and the problem seems to have been cleared up for me. That includes making sure the grub2 file has the gfxterm set, etc. I know we've been seeing this quite a bit more on Fedora 17, so we'll want to have some people test a 3.5 build with it but things are looking better. josh -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
