On Monday 29 June 2015 09:57 PM, Daniel Vetter wrote:
On Mon, Jun 29, 2015 at 04:52:14PM +0530, Ramalingam C wrote:
On Friday 26 June 2015 10:46 PM, Daniel Vetter wrote:
On Fri, Jun 26, 2015 at 07:21:44PM +0530, Ramalingam C wrote:
- Static DRRS and generalized seamless DRRS are imo separate features and
we should split the patch series. seamless DRRS is already implemented
using the fb tracking, maybe extended with some hints to userspace.
Static DRRS otoh is just a modeset with a different clock (plus a better
internal implementation to avoid flicker). So from that pov two
completely different features, both in the implementation and the
userspace ABI.
Yup. Static is not even in our development radar :). All the code that I
have shared is
concerned only with seamless DRRS and it's two usecase scenarios( Idleness
and Content based).
Mentioned the Static DRRS in cover letter, just to give the two different
DRRS supports available in general.
Hm then I'm confused how the content based DRRS is supposed to work. I
thought userspace requires a precise vrefresh rate (adjusted to content,
within the limits of what the panel can do ofc) and the kernel tries to
obey. That's what I consider static DRRS, i.e. userspace makes a fixed
request, kernel executes it exactly.
If panel does support the static DRRS only and you are ok to do a
complete modeset on a usecase then
Whatever you have explained stands true for content based DRRS. I
believe its another complete modeset w.r.t kernel.
Which I am not addressing in this RFC.
But If the panel supports seamless DRRS and userspace want a precise
vrefresh rate (adjusted to the
content, within the limits of what panel can do) then kernel can achieve
the vrefresh change seamlessly
(the way its done with Idleness scenario). This is the second usecase of
seamless DRRS support of the panel.
Infact We have implemented this and verified on android already for
video playback.
Seamless DRRS for me is when the kernel tries to change vrefresh when
everything is idle behind everyone's back.
Seamless DRRS is a capability of the host and the panel. Usercase
definition is upto us to do.
I'm doing this split since seamless doesn't require new userspace
interfaces (we just use the frontbuffer tracking system), whereas static
needs explicit action from userspace and hence the dreaded userspace ABI
problem starts to kick in.
Based on above usecase of the seamless drrs we need a fast modeset path
which I have addressed at the RFC PATCH 16/18.
And drm connector property to expose the SEAMLESS DRRS capability to the
userspace. implemented at RFC PATCH 18/18
Do you have different definitions? What exactly are those?
-Daniel
--
Thanks,
--Ram
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