Re: [RFC 0/6] eDP DRRS based on frontbuffer tracking

From: Daniel Vetter <daniel@ffwll.ch>
To: "Kannan, Vandana" <vandana.kannan@intel.com>
Cc: "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>
Subject: Re: [RFC 0/6] eDP DRRS based on frontbuffer tracking
Date: Fri, 28 Nov 2014 18:17:22 +0100	[thread overview]
Message-ID: <20141128171722.GD32117@phenom.ffwll.local> (raw)
In-Reply-To: <54785202.3030706@intel.com>

On Fri, Nov 28, 2014 at 04:14:18PM +0530, Kannan, Vandana wrote:
> 
> 
> On 23-Sep-14 2:31 PM, Daniel Vetter wrote:
> >On Fri, Sep 12, 2014 at 11:13:03PM +0530, Vandana Kannan wrote:
> >>As part of implementing DRRS based on frontbuffer tracking, this patch series
> >>includes some modifications related to the data for DRRS, code to enable/
> >>disable DRRS during init or uninit, calls to switch between high and low
> >>refresh rates based on calls to mark_fb_busy.
> >>Instead of having a module param to specify delay before scheduling DRRS
> >>work, (as there was in the old patch series), a delay of 100ms is used.
> >>Additional patches including changes specific to bdw and vlv have been
> >>included.
> >
> >Sorry for the delay in answering, been a bit busy. Looks good overall,
> >just spotted a few issue with the integration into the frontbuffer
> >tracking. That's probably just because the documentation we have is awful,
> >so I've improved that and replied with what I think we need.
> >
> Hi Daniel,
> 
> Sorry for the delay on this. I've been working on and off on it.
> I went through the comment added in intel_frontbuffer.c, and just wanted to
> confirm if my understanding is correct.
> 
> In intel_frontbuffer.c, we have the comment
> "
>  * The other type of display power saving feature only cares about busyness
>  * (e.g. DRRS). In that case all three (invalidate, flush and flip) indicate
>  * busyness. There is no direct way to detect idleness.
> "
> Here, flip refers to intel_crtc_page_flip?
> Since a flip also indicates busyness, it would mean that a switch back to
> high RR (invalidate DRRS) would be required at this point ? (apart from the
> GEM tracking).
> 
> Please let me know.

Yes - the comment says that all 3 indicate busyness for stuff like DRRS.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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