[RFC PATCH xserver] modesetting: re-set the crtc's mode when link-status goes BAD

[Manasi Navare]

On Mon, Apr 03, 2017 at 09:19:35AM +0200, Daniel Vetter wrote:
> On Mon, Apr 3, 2017 at 8:25 AM, Manasi Navare <manasi.d.navare at intel.com> wrote:
> >> So in that case you do need userspace to re-request the same mode at the
> >> same bpp?
> >
> > So yes because when userspace requests the same mode at same bpp,
> > kernel will still call intel_dp->mod_valid which validates the mode
> > against 18bpp so if the requested mode can be displayed at the lowest of
> > 18bpp, then the kernel will try to do the modeset for that mode at lower
> > bpp. What I am trying to say is irrespective of what bpp userspace requests,
> > kernel will check if it can display that at the lowest of 18bpp.
> 
> You're talking about two different bpp here I think. Eric talks about
> the pixel format of the framebuffer, Manasi here about the bpp we send
> over the wire. The kernel will auto-dither if the wire bpp is lower
> than the stuff we scan out. Same with 6bpc panels really.
> 
> Right now userspace can't request a specific bpp for the sink/pipe,
> that's fully under the kernel's control. It only gets to set the pixel
> format of fbs.
> -Daniel
> -- 

Yes so in that case, Eric we do need userspace to re-request the same mode
at the same bpp or the same pixel format. 
And if this also fails, then we need Gnome or KDE to be re triggering a
complete re probe.

Regards
Manasi


> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch