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libretro: don't rebuild the video driver for an unchanged mode #160

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Merged
LibretroAdmin merged 1 commit into from
Aug 28, 2026
Merged

libretro: don't rebuild the video driver for an unchanged mode #160

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55 changes: 54 additions & 1 deletion libretro/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@

#include "libretro_core_options.h"

#include <cmath>
#include "../pcsx2/GS.h"
#include "../pcsx2/SPU2/Global.h"
#include "../pcsx2/ps2/BiosTools.h"
Expand Down Expand Up @@ -2825,12 +2826,64 @@ void retro_unload_game(void)
retro_set_region(RETRO_REGION_NTSC); /* set back to default */
}

/* SET_SYSTEM_AV_INFO makes the frontend tear down and rebuild its whole video
* driver - on the HW-render path that means context_destroy and a fresh
* negotiation - so it is only worth sending for a change that actually needs
* one. Announcing unconditionally cost a full video and audio driver reinit
* every time the VM reported its mode, including reports identical to the last
* one, and put that rebuild in the way of a GS thread still submitting to the
* shared Vulkan queue.
*
* Two guards, both taken from the same fix in pcee2:
*
* - Only announce on a real timing change. The fps compare needs a tolerance:
* NTSC reports 59.94005994 Hz against a 59.94 default and that 0.00006 Hz
* difference must not rebuild anything. Geometry does not need an announce
* at all on the HW-render path - SET_GEOMETRY carries it without a reinit,
* which is how the widescreen hint already does it.
* - Drain the GS thread before an announce that does go out, so no queued work
* races the frontend's reinit. The CPU thread is already parked here:
* retro_run has not resumed it yet. */
static void update_av_info(void)
{
retro_system_av_info av_info;
retro_get_system_av_info(&av_info);
environ_cb(RETRO_ENVIRONMENT_SET_SYSTEM_AV_INFO, &av_info);
pending_update_av_info = false;

static bool have_last = false;
static double last_fps = 0.0;
static double last_sample_rate = 0.0;
static unsigned last_width = 0;
static unsigned last_height = 0;
static float last_aspect = 0.0f;

const bool hw_vulkan = (hw_render.context_type == RETRO_HW_CONTEXT_VULKAN);
const bool timing_changed = !have_last
|| std::fabs(av_info.timing.fps - last_fps) > 0.25
|| av_info.timing.sample_rate != last_sample_rate;
const bool geometry_changed = !have_last
|| av_info.geometry.base_width != last_width
|| av_info.geometry.base_height != last_height
|| std::fabs(av_info.geometry.aspect_ratio - last_aspect) > 0.001f;

have_last = true;
last_fps = av_info.timing.fps;
last_sample_rate = av_info.timing.sample_rate;
last_width = av_info.geometry.base_width;
last_height = av_info.geometry.base_height;
last_aspect = av_info.geometry.aspect_ratio;

if (!timing_changed && (hw_vulkan || !geometry_changed))
{
if (geometry_changed)
environ_cb(RETRO_ENVIRONMENT_SET_GEOMETRY, &av_info.geometry);
return;
}

if (hw_vulkan && MTGS::IsOpen())
MTGS::WaitGS(false);

environ_cb(RETRO_ENVIRONMENT_SET_SYSTEM_AV_INFO, &av_info);
}

void retro_run(void)
Expand Down