[Mesa-dev] [PATCH] egl/dri2: Implement swapInterval fallback in a conformant way (v2)
Tapani Pälli
tapani.palli at intel.com
Fri Aug 11 04:21:06 UTC 2017
Reviewed-by: Tapani Pälli <tapani.palli at intel.com>
On 08/10/2017 04:59 PM, Tomasz Figa wrote:
> dri2_fallback_swap_interval() currently used to stub out swap interval
> support in Android backend does nothing besides returning EGL_FALSE.
> This causes at least one known application (Android Snapchat) to fail
> due to an unexpected error and my loose interpretation of the EGL 1.5
> specification justifies it. Relevant quote below:
>
> The function
>
> EGLBoolean eglSwapInterval(EGLDisplay dpy, EGLint interval);
>
> specifies the minimum number of video frame periods per buffer swap
> for the draw surface of the current context, for the current rendering
> API. [...]
>
> The parameter interval specifies the minimum number of video frames
> that are displayed before a buffer swap will occur. The interval
> specified by the function applies to the draw surface bound to the
> context that is current on the calling thread. [...] interval is
> silently clamped to minimum and maximum implementation dependent
> values before being stored; these values are defined by EGLConfig
> attributes EGL_MIN_SWAP_INTERVAL and EGL_MAX_SWAP_INTERVAL
> respectively.
>
> The default swap interval is 1.
>
> Even though it does not specify the exact behavior if the platform does
> not support changing the swap interval, the default assumed state is the
> swap interval of 1, which I interpret as a value that eglSwapInterval()
> should succeed if called with, even if there is no ability to change the
> interval (but there is no change requested). Moreover, since the
> behavior is defined to clamp the requested value to minimum and maximum
> and at least the default value of 1 must be present in the range, the
> implementation might be expected to have a valid range, which in case of
> the feature being unsupported, would correspond to {1} and any request
> might be expected to be clamped to this value.
>
> Fix this by defaulting dri2_dpy's min_swap_interval, max_swap_interval
> and default_swap_interval to 1 in dri2_setup_screen() and let platforms,
> which support this functionality set their own values after this
> function returns. Thanks to patches merged earlier, we can also remove
> the dri2_fallback_swap_interval() completely, as with a singular range
> it would not be called anyway.
>
> v2: Remove dri2_fallback_swap_interval() completely thanks to higher
> layer already clamping the requested interval and not calling the
> driver layer if the clamped value is the same as current.
>
> Signed-off-by: Tomasz Figa <tfiga at chromium.org>
> ---
> src/egl/drivers/dri2/egl_dri2.c | 12 ++++++++++++
> src/egl/drivers/dri2/egl_dri2_fallbacks.h | 7 -------
> src/egl/drivers/dri2/platform_android.c | 1 -
> src/egl/drivers/dri2/platform_drm.c | 1 -
> src/egl/drivers/dri2/platform_surfaceless.c | 1 -
> src/egl/drivers/dri2/platform_x11.c | 2 +-
> 6 files changed, 13 insertions(+), 11 deletions(-)
>
> diff --git a/src/egl/drivers/dri2/egl_dri2.c b/src/egl/drivers/dri2/egl_dri2.c
> index f0d1ded408..686dd68d29 100644
> --- a/src/egl/drivers/dri2/egl_dri2.c
> +++ b/src/egl/drivers/dri2/egl_dri2.c
> @@ -630,6 +630,18 @@ dri2_setup_screen(_EGLDisplay *disp)
> struct dri2_egl_display *dri2_dpy = dri2_egl_display(disp);
> unsigned int api_mask;
>
> + /*
> + * EGL 1.5 specification defines the default value to 1. Moreover,
> + * eglSwapInterval() is required to clamp requested value to the supported
> + * range. Since the default value is implicitly assumed to be supported,
> + * use it as both minimum and maximum for the platforms that do not allow
> + * changing the interval. Platforms, which allow it (e.g. x11, wayland)
> + * override these values already.
> + */
> + dri2_dpy->min_swap_interval = 1;
> + dri2_dpy->max_swap_interval = 1;
> + dri2_dpy->default_swap_interval = 1;
> +
> if (dri2_dpy->image_driver) {
> api_mask = dri2_dpy->image_driver->getAPIMask(dri2_dpy->dri_screen);
> } else if (dri2_dpy->dri2) {
> diff --git a/src/egl/drivers/dri2/egl_dri2_fallbacks.h b/src/egl/drivers/dri2/egl_dri2_fallbacks.h
> index 604db881a8..a664677572 100644
> --- a/src/egl/drivers/dri2/egl_dri2_fallbacks.h
> +++ b/src/egl/drivers/dri2/egl_dri2_fallbacks.h
> @@ -55,13 +55,6 @@ dri2_fallback_create_image_khr(_EGLDriver *drv, _EGLDisplay *disp,
> return NULL;
> }
>
> -static inline EGLBoolean
> -dri2_fallback_swap_interval(_EGLDriver *drv, _EGLDisplay *dpy,
> - _EGLSurface *surf, EGLint interval)
> -{
> - return EGL_FALSE;
> -}
> -
> static inline EGLBoolean
> dri2_fallback_swap_buffers_with_damage(_EGLDriver *drv, _EGLDisplay *dpy,
> _EGLSurface *surf,
> diff --git a/src/egl/drivers/dri2/platform_android.c b/src/egl/drivers/dri2/platform_android.c
> index 50a8248695..c1bae34f2d 100644
> --- a/src/egl/drivers/dri2/platform_android.c
> +++ b/src/egl/drivers/dri2/platform_android.c
> @@ -1118,7 +1118,6 @@ static const struct dri2_egl_display_vtbl droid_display_vtbl = {
> .create_pbuffer_surface = droid_create_pbuffer_surface,
> .destroy_surface = droid_destroy_surface,
> .create_image = droid_create_image_khr,
> - .swap_interval = dri2_fallback_swap_interval,
> .swap_buffers = droid_swap_buffers,
> .swap_buffers_with_damage = dri2_fallback_swap_buffers_with_damage,
> .swap_buffers_region = dri2_fallback_swap_buffers_region,
> diff --git a/src/egl/drivers/dri2/platform_drm.c b/src/egl/drivers/dri2/platform_drm.c
> index a952aa5456..8edfbcd07c 100644
> --- a/src/egl/drivers/dri2/platform_drm.c
> +++ b/src/egl/drivers/dri2/platform_drm.c
> @@ -674,7 +674,6 @@ static const struct dri2_egl_display_vtbl dri2_drm_display_vtbl = {
> .create_pbuffer_surface = dri2_fallback_create_pbuffer_surface,
> .destroy_surface = dri2_drm_destroy_surface,
> .create_image = dri2_drm_create_image_khr,
> - .swap_interval = dri2_fallback_swap_interval,
> .swap_buffers = dri2_drm_swap_buffers,
> .swap_buffers_with_damage = dri2_fallback_swap_buffers_with_damage,
> .swap_buffers_region = dri2_fallback_swap_buffers_region,
> diff --git a/src/egl/drivers/dri2/platform_surfaceless.c b/src/egl/drivers/dri2/platform_surfaceless.c
> index 1091b4febd..678dc88532 100644
> --- a/src/egl/drivers/dri2/platform_surfaceless.c
> +++ b/src/egl/drivers/dri2/platform_surfaceless.c
> @@ -234,7 +234,6 @@ static const struct dri2_egl_display_vtbl dri2_surfaceless_display_vtbl = {
> .create_pbuffer_surface = dri2_surfaceless_create_pbuffer_surface,
> .destroy_surface = surfaceless_destroy_surface,
> .create_image = dri2_create_image_khr,
> - .swap_interval = dri2_fallback_swap_interval,
> .swap_buffers = surfaceless_swap_buffers,
> .swap_buffers_with_damage = dri2_fallback_swap_buffers_with_damage,
> .swap_buffers_region = dri2_fallback_swap_buffers_region,
> diff --git a/src/egl/drivers/dri2/platform_x11.c b/src/egl/drivers/dri2/platform_x11.c
> index 4610ec579f..122e4c193d 100644
> --- a/src/egl/drivers/dri2/platform_x11.c
> +++ b/src/egl/drivers/dri2/platform_x11.c
> @@ -1139,7 +1139,6 @@ static const struct dri2_egl_display_vtbl dri2_x11_swrast_display_vtbl = {
> .create_pbuffer_surface = dri2_x11_create_pbuffer_surface,
> .destroy_surface = dri2_x11_destroy_surface,
> .create_image = dri2_create_image_khr,
> - .swap_interval = dri2_fallback_swap_interval,
> .swap_buffers = dri2_x11_swap_buffers,
> .set_damage_region = dri2_fallback_set_damage_region,
> .swap_buffers_region = dri2_fallback_swap_buffers_region,
> @@ -1283,6 +1282,7 @@ dri2_x11_setup_swap_interval(struct dri2_egl_display *dri2_dpy)
> */
> dri2_dpy->min_swap_interval = 0;
> dri2_dpy->max_swap_interval = 0;
> + dri2_dpy->default_swap_interval = 0;
>
> if (!dri2_dpy->swap_available)
> return;
>
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