Linux: Smooth splashscreen with system having weston with drm-backend

[Sean Paul]

On Thu, Jul 13, 2017 at 03:50:56PM +0200, Daniel Vetter wrote:
> On Thu, Jul 13, 2017 at 3:33 PM, Vikas Patil <vikasmpatil at gmail.com> wrote:
> > Dear All,
> >
> > I am looking for an solution to have early smooth splashscreen on the
> > Linux system with Weston and drm-backend.
> >
> > I tried showing splashscreen using Linux logo and fbcon Linux features
> > but it is not smooth as when system boots logo gets displayed via
> > kernel and as the Weston starts
> > I see flicker and blackscreen.
> >
> > Another approach I tried is having standalone drm api based
> > application [1] which uses the one of the available hardware
> > plane/overlay for displaying splash image and Weston is
> > starting and uses default plane which is different from plane utilized
> > by above application. but still I see flicker and black screen when
> > Weston starts.
> >
> > I want splash to be displayed on one of the h/w plane and Weston
> > should start in background without any flicker and black screen on
> > some other plane.
> >
> > Anyone here before achieved such a use case with such system? Looking
> > for inputs/suggestions/ideas to achieve this. It is ok if something
> > needs to be hacked/changd at any level (kernel driver, weston).
> >
> > This is required on platform such as TI (Jacinto) and Intel (Broxton)
> > or devices based on drm graphics stack.
> >
> > [1] http://git.ti.com/glsdk/example-applications/blobs/39080525baca7bf136f2412d62436366a736af6b/drm-tests/drm_z_alpha.c
> >
> > Thanking you all for your time and inputs in advance.
> 
> If you make sure you have matching modes between the 2 users of drm
> this should work. kms drivers (especially if they are already
> converted to atomic) will automatically optimize transitions to not
> flicker (if possible).
> 
> If you still flicker then it's either a kernel driver issue, a hw
> limitations (some hw needs a full modeset for e.g. changing the bit
> depth) or you program two different things.
> 
> Also, you must ensure that the boot-splash does not quit until weston
> has fully taken over, otherwise kms will first shut down the screen
> (when the splash quits), then re-enable it when weston starts.
> 

This is what we do in Chrome OS with frecon [1]. It presents the splash screen
until Chrome is ready to take over.

[1]- https://chromium.googlesource.com/chromiumos/platform/frecon

Sean


> Cheers, Daniel
> 
> >
> > Thanks & Regards,
> > Vikash
> > _______________________________________________
> > wayland-devel mailing list
> > wayland-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/wayland-devel
> 
> 
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
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-- 
Sean Paul, Software Engineer, Google / Chromium OS