Reg. Adaptive Sync feature in xf86-video-amdgpu

[uday kiran pichika]

Thanks for the information Michel.

Even in amdgpu_present_flip(), there is a check
for amdgpu_window_has_variable_refresh() which actually checks whether
window has a variable_refresh property set from the MESA or not ? this
check is failing in my case and never calls amdgpu_present_set_screen_vrr.
Is there any way that i can check whether MESA is setting this property ?

To my understanding, MESA will set this property to true or false based on
whether application is running in Full screen mode or in normal mode.
Please correct me if I am wrong.

Thanks
Uday Kiran

On Mon, Apr 20, 2020 at 8:14 PM Michel Dänzer <michel at daenzer.net> wrote:

> On 2020-04-20 6:12 a.m., uday kiran pichika wrote:
> > Hello Team,
> >
> > I'm working on adding Adaptive Sync feature in Xserver/modesetting. When
> > understanding the existing AMD's implementation, I've few doubts
> regarding
> > the vrr property being set on the Window from MESA.
> >
> > I have made the modifications in xserver/modesetting but when i launch
> the
> > application(DOTA2), below condition gets failed
> >
> https://gitlab.freedesktop.org/xorg/driver/xf86-video-amdgpu/-/blob/master/src/amdgpu_kms.c#L110
>
> BTW, one should always use a specific Git commit for this kind of
> reference, otherwise it will tend to point to unrelated code or even
> nirvana as time passes.
>
>
> > As per the code, i had a confusion that this condition will never met.
> >
> > *I had analysed the code and here is the analysis made when the flip
> > happens in xserver When full screen gaming application is opened,
> > variable_refresh property is being set in MESA and xserver will get
> > notified with amdgpu_change_property() method(Same method we registered
> > with the client during AMDGPUScreenInit_KMS()). *
> >
> > *Below actions will happen in ms_change_property() *
> >
> > *1. Create Local WindowPtr and copy the data from Stuff->window to this
> > WindowPtr*
> >
> > *2. Call amdgpu_vrr_property_update() based on the property set in Stuff
> by
> > passing the WindowPtr to it.*
> >
> > *    a. Read Private Keys for WindowPtr in amdgpu_vrr_property_update().
> *
> >
> > *    b. Compare info->flip_window and this WindowPtr and make a call to
> > amdgpu_present_set_screen_vrr().  → But this method will never gets
> called
> > due to the condition mismatch every time. Why ? *
> >
> > *Why ?*
> >
> > *info->flip_window gets updated with window (WindowPtr)
> > in amdgpu_present_check_flip() when amdgpu_present_flip() method gets
> > called from DIX. This pointer will never same as the WindowPtr created in
> > amdgpu_change_property() and variable_refresh flag is being set for in
> > amdgpu_change_property() WindowPtr only. *
> >
> > Can  you please help me in understanding on this ?
>
> This code in amdgpu_vrr_property_update is for the case when the
> ChangeProperty request is called for a window which is already flipping.
>
> In the case you're looking at, the window only starts flipping later,
> and the KMS property is enabled from amdgpu_present_flip =>
> amdgpu_present_set_screen_vrr.
>
>
> --
> Earthling Michel Dänzer               |               https://redhat.com
> Libre software enthusiast             |             Mesa and X developer
>
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