On 2018-10-05 10:43 p.m., Nicholas Kazlauskas wrote:
> The DDX driver can be notified of adaptive sync suitability by
> flagging the application's window with the _VARIABLE_REFRESH property.
>
> This property is set on the first swap the application performs
> when adaptive_sync_enable is set to true in the drirc.
>
> It's performed here instead of when the loader is initialized for
> two reasons:
>
> (1) The window's drawable can be missing during loader init.
> This can be observed during the Unigine Superposition benchmark.
>
> (2) Adaptive sync will only be enabled closer to when the application
> actually begins rendering. For some displays this means there is
> less time spent watching flickering occur during application load.
>
> For now this property is only set on the glx DRI3 backend. This should
> cover most common applications and games on modern hardware.
>
> Vulkan support can be implemented in a similar manner but would likely
> require splitting the function out into a common helper function.
>
> Signed-off-by: Nicholas Kazlauskas <nicholas.kazlaus...@amd.com>
>
> [...]
>
> @@ -331,16 +360,25 @@ loader_dri3_drawable_init(xcb_connection_t *conn,
> draw->have_back = 0;
> draw->have_fake_front = 0;
> draw->first_init = true;
> + draw->adaptive_sync_enable = false;
> + draw->adaptive_sync_active = false;
>
> draw->cur_blit_source = -1;
> draw->back_format = __DRI_IMAGE_FORMAT_NONE;
> mtx_init(&draw->mtx, mtx_plain);
> cnd_init(&draw->event_cnd);
>
> - if (draw->ext->config)
> + if (draw->ext->config) {
> draw->ext->config->configQueryi(draw->dri_screen,
> "vblank_mode", &vblank_mode);
>
> + draw->ext->config->configQueryb(draw->dri_screen,
> + "adaptive_sync_enable",
> + &adaptive_sync_enable);
> +
> + draw->adaptive_sync_enable = adaptive_sync_enable;
> + }
> +
> switch (vblank_mode) {
> case DRI_CONF_VBLANK_NEVER:
> case DRI_CONF_VBLANK_DEF_INTERVAL_0:
> @@ -879,6 +917,12 @@ loader_dri3_swap_buffers_msc(struct loader_dri3_drawable
> *draw,
> back = dri3_find_back_alloc(draw);
>
> mtx_lock(&draw->mtx);
> +
> + if (draw->adaptive_sync_enable && !draw->adaptive_sync_active) {
> + set_adaptive_sync_property(draw->conn, (xcb_window_t)draw->drawable,
> true);
> + draw->adaptive_sync_active = true;
> + }
The window property should also either be deleted, or its value set to
0, when adaptive_sync_enable is false, to address the following scenario:
1. Xorg is running without a compositor, and the user runs an OpenGL app
which draws to the root window, e.g. an xscreensaver hack.
2. Later, the user starts a compositor which draws to the root window.
Step one sets the window property to 1, so without the above, the
compositor will use variable refresh even if it's blacklisted.
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Mesa and X developer
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