Re: Fwd: [PATCH] drm/i915: Fix IPS related flicker

Jani Nikula
2015-06-18T12:00:47Z

On Thu, 18 Jun 2015, Jani Nikula <jani.nikula@linux.intel.com> wrote:
> On Thu, 18 Jun 2015, Ander Conselvan De Oliveira <conselvan2@gmail.com> wrote:
>> On Fri, 2015-06-05 at 12:11 +0300, Ville Syrjälä wrote:
>>> On Fri, Jun 05, 2015 at 11:51:42AM +0300, Jani Nikula wrote:
>>> > On Thu, 04 Jun 2015, Rodrigo Vivi <rodrigo.vivi@gmail.com> wrote:
>>> > > I just noticed that I had forgotten to reply-all...
>>> > >
>>> > > Jani, would you consider merge this fix with the explanation above
>>> > > related to Ville's question?
>>> > >
>>> > > or do you want/need any action here?
>>> >
>>> > Ville's question, I'd like Ville's ack on it.
>>>
>>> It's good enough for me. This part of the driver is a quite a mess
>>> anyway currently, so doesn't matter too much what we stick in there.
>>
>> Ping. Seems like this still isn't merged. Does it need more work or did
>> it just fall through the cracks?
>
> It fell between the cracks. I know the world isn't black and white, but
> it doesn't help the maintainers when review is some shade of grey.
>
> I've pushed this to drm-intel-next-fixes for now, but it has missed the
> train for both the v4.1 release and the main drm-next feature pull
> request for the v4.2 merge window. I expect this to land upstream in
> v4.2-rc2, unless there's an additional drm-next pull request during the
> merge window. I've added cc: stable.
>
> Thanks for the patch, and I guess the review was, uh, "good enough for
> me" now... :p

Argh, I'll take that back. This conflicts with dinq, and while doing so
also confuses git rerere enough to uncover a previous much bigger
conflict that I have no intention of resolving again before the
weekend. I'll return to it next week. Sorry.

BR,
Jani.

>
> BR,
> Jani.
>
>
>>
>> Thanks,
>> Ander
>>
>>>
>>> >
>>> > BR,
>>> > Jani.
>>> >
>>> >
>>> > >
>>> > > Thanks,
>>> > > Rodrigo.
>>> > >
>>> > >
>>> > > ---------- Forwarded message ----------
>>> > > From: Rodrigo Vivi <rodrigo.vivi@gmail.com>
>>> > > Date: Fri, May 29, 2015 at 9:45 AM
>>> > > Subject: Re: [Intel-gfx] [PATCH] drm/i915: Fix IPS related flicker
>>> > > To: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>> > >
>>> > >
>>> > > On Fri, May 29, 2015 at 1:47 AM, Ville Syrjälä
>>> > > <ville.syrjala@linux.intel.com> wrote:
>>> > >> On Thu, May 28, 2015 at 11:07:11AM -0700, 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." This restriction apply to HSW and BDW.
>>> > >>>
>>> > >>> However a shortcut path on update primary plane function
>>> > >>> to make primary plane invisible by setting DSPCTRL to 0
>>> > >>> 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.
>>> > >>>
>>> > >>> v2: Don't mess with Atomic path as pointed out by Ville.
>>> > >>>
>>> > >>> Reference: https://bugs.freedesktop.org/show_bug.cgi?id=85583
>>> > >>> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>> > >>> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
>>> > >>> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
>>> > >>> ---
>>> > >>> drivers/gpu/drm/i915/intel_display.c | 13 +++++++++++++
>>> > >>> drivers/gpu/drm/i915/intel_drv.h | 1 +
>>> > >>> 2 files changed, 14 insertions(+)
>>> > >>>
>>> > >>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>>> > >>> index 4e3f302..5a6b17b 100644
>>> > >>> --- a/drivers/gpu/drm/i915/intel_display.c
>>> > >>> +++ b/drivers/gpu/drm/i915/intel_display.c
>>> > >>> @@ -13309,6 +13309,16 @@ intel_check_primary_plane(struct drm_plane *plane,
>>> > >>> intel_crtc->atomic.wait_vblank = true;
>>> > >>> }
>>> > >>>
>>> > >>> + /*
>>> > >>> + * FIXME: Actually if we will still have any other plane enabled
>>> > >>> + * on the pipe we could let IPS enabled still, but for
>>> > >>> + * now lets consider that when we make primary invisible
>>> > >>> + * by setting DSPCNTR to 0 on update_primary_plane function
>>> > >>> + * IPS needs to be disable.
>>> > >>> + */
>>> > >>> + if (!state->visible || !fb)
>>> > >>> + intel_crtc->atomic.disable_ips = true;
>>> > >>> +
>>> > >>
>>> > >> How could it be visible without an fb?
>>> > >
>>> > > I don't like this !fb here as well, but I just tried to keep exactly
>>> > > same if statement that makes I915_WRITE(DSPCNTRL, 0) on update primary
>>> > > plane func...
>>> > >
>>> > >>
>>> > >>> intel_crtc->atomic.fb_bits |=
>>> > >>> INTEL_FRONTBUFFER_PRIMARY(intel_crtc->pipe);
>>> > >>>
>>> > >>> @@ -13406,6 +13416,9 @@ static void intel_begin_crtc_commit(struct drm_crtc *crtc)
>>> > >>> if (intel_crtc->atomic.disable_fbc)
>>> > >>> intel_fbc_disable(dev);
>>> > >>>
>>> > >>> + if (intel_crtc->atomic.disable_ips)
>>> > >>> + hsw_disable_ips(intel_crtc);
>>> > >>> +
>>> > >>> if (intel_crtc->atomic.pre_disable_primary)
>>> > >>> intel_pre_disable_primary(crtc);
>>> > >>
>>> > >> intel_pre_disable_primary() would already disable IPS. Except no one
>>> > >> sets .pre_disable_primary=true. OTOH that thing mostly seems to do
>>> > >> stuff that has nothing to do with the primary plane (cxsr disable,
>>> > >> fifo underrun reporting disable on gen2), so I don't think we want
>>> > >> to use that.
>>> > >>
>>> > >> In any case we should really have the IPS state as part of the crtc
>>> > >> state. These global disable_foo things should just be killed IMO.
>>> > >> Hmm, except to do this properly we'd then need to track the hw IPS
>>> > >> state separately somewhere.
>>> > >
>>> > > agree.
>>> > >
>>> > >>
>>> > >> I guess we can just go with this for now. At least it's not really
>>> > >> making things worse, so (maybe with the !fb check dropped):
>>> > >> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>> > >
>>> > > Thanks
>>> > >
>>> > >>
>>> > >>>
>>> > >>> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
>>> > >>> index 2afb31a..1059283 100644
>>> > >>> --- a/drivers/gpu/drm/i915/intel_drv.h
>>> > >>> +++ b/drivers/gpu/drm/i915/intel_drv.h
>>> > >>> @@ -485,6 +485,7 @@ struct intel_crtc_atomic_commit {
>>> > >>> /* Sleepable operations to perform before commit */
>>> > >>> bool wait_for_flips;
>>> > >>> bool disable_fbc;
>>> > >>> + bool disable_ips;
>>> > >>> bool pre_disable_primary;
>>> > >>> bool update_wm;
>>> > >>> unsigned disabled_planes;
>>> > >>> --
>>> > >>> 2.1.0
>>> > >>
>>> > >> --
>>> > >> Ville Syrjälä
>>> > >> Intel OTC
>>> > >> _______________________________________________
>>> > >> Intel-gfx mailing list
>>> > >> Intel-gfx@lists.freedesktop.org
>>> > >> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>> > >
>>> > >
>>> > >
>>> > > --
>>> > > Rodrigo Vivi
>>> > > Blog: http://blog.vivi.eng.br
>>> > >
>>> > >
>>> > > --
>>> > > Rodrigo Vivi
>>> > > Blog: http://blog.vivi.eng.br
>>> >
>>> > --
>>> > Jani Nikula, Intel Open Source Technology Center
>>> > _______________________________________________
>>> > Intel-gfx mailing list
>>> > Intel-gfx@lists.freedesktop.org
>>> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>>
>>
>>
>
> --
> Jani Nikula, Intel Open Source Technology Center

--
Jani Nikula, Intel Open Source Technology Center