[Intel-gfx] [RFC xf86-video-intel] sna: Call dirtyfb for all non-tear-free cases

[Zanoni, Paulo R]

Em Ter, 2016-03-22 às 12:31 +0100, Daniel Vetter escreveu:
> On Mon, Mar 21, 2016 at 04:26:55PM -0300, Paulo Zanoni wrote:
> > 
> > The sna_mode_wants_tear_free() function tries to detect FBC and PSR
> > based on Kernel module parameters. Currently it fails to detect FBC
> > due to the default enable_fbc value being -1. While this can easily
> > be
> > fixed in the Kernel, I had a conversation with Daniel and he
> > expressed
> > unhappiness with that solution, claiming that yet another different
> > code path just for a feature that should be transparent is not a
> > good
> > way to go, and that we should do proper frontbuffer rendering.
> > 
> > So with this patch, we'll have the DDX issuing dirtyfb calls even
> > if
> > TearFree is not enabled, fixing FBC when i915.enable_fbc=-1.
> > 
> > This fixes a bug that happens on SKL with FBC enabled: if you run
> > lightdm, your login/password won't appear as you type on your
> > keyboard. You have to move the mouse over the input box for them to
> > be
> > displayed.
> > 
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
> I thought we need this anyway to get the kernel to allow fbc, since
> SNA
> ends up mmap some of the drm_framebuffer. Even when they're not
> frontbuffers.

If we merge patch 2/4, we won't need this one since TearFree will be in
use, and it seems TearFree doesn't touch frontbuffers, so we'll always
get the flush calls during page flips.

> -Daniel
> 
> > 
> > ---
> >  src/sna/sna_driver.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/src/sna/sna_driver.c b/src/sna/sna_driver.c
> > index b245594..84e8e55 100644
> > --- a/src/sna/sna_driver.c
> > +++ b/src/sna/sna_driver.c
> > @@ -654,7 +654,7 @@ static Bool sna_pre_init(ScrnInfoPtr scrn, int
> > probe)
> >  	}
> >  	scrn->currentMode = scrn->modes;
> >  
> > -	if (!setup_tear_free(sna) &&
> > sna_mode_wants_tear_free(sna))
> > +	if (!setup_tear_free(sna))
> >  		sna->kgem.needs_dirtyfb = sna->kgem.has_dirtyfb;
> >  
> >  	xf86SetGamma(scrn, zeros);
> > -- 
> > 2.7.0
> > 
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