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

[Daniel Vetter]

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.
-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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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch