On Thursday, May 21, 2015 12:53:03 PM Rodrigo Vivi wrote: > We cannot let IPS enabled with no plane on the pipe: > > BSpec: "IPS cannot be enabled until after at least one plane has > been enabled for at least one vertical blank." and "IPS must be > disabled while there is still at least one plane enabled on the > same pipe as IPS. > > However this shortcut path to make primary plane invisible when > updating primary plane was leting IPS enabled while there was no > other plane enabled on the pipe causing flickerings that we were > believing that it was caused by that other restriction where > ips cannot be used when pixel rate is greater than 95% of cdclok. > > Reference: https://bugs.freedesktop.org/show_bug.cgi?id=85583 > Cc: Joe Konno <joe.konno@xxxxxxxxx> > Cc: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_display.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c > index 9d2d6fb..5519d56 100644 > --- a/drivers/gpu/drm/i915/intel_display.c > +++ b/drivers/gpu/drm/i915/intel_display.c > @@ -2789,6 +2789,19 @@ static void ironlake_update_primary_plane(struct drm_crtc *crtc, > int pixel_size; > > if (!visible || !fb) { > + /* > + * This shortcut path disables the primary plane making > + * IPS really sad and lost when it is enabled alone with no > + * plane around on the pipe. So, for now it is safe to disable > + * IPS here. > + / > + /* > + * FIXME: Any other plane enabled should be enough so it would > + * be better to check if there is really no sprite or > + * cursor around. > + */ > + hsw_disable_ips(intel_crtc); > + > I915_WRITE(reg, 0); > I915_WRITE(DSPSURF(plane), 0); > POSTING_READ(reg); This fixes a bug on my Lenovo X250 (Broadwell GT2). 1. Boot 2. startx using SNA and KDE 5 3. Quit X Prior to this patch, the screen was all scrambled. With this patch, it works perfectly. Thanks, Rodrigo! Tested-by: Kenneth Graunke <kenneth@xxxxxxxxxxxxx>
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