S3 ViRGE: Make IRQs happen in main thread

FIFO is also no longer immediately woken up upon writes

src/video/vid_s3_virge.c

@@ -338,6 +338,7 @@ typedef struct virge_t {
     event_t *    fifo_not_full_event;
 
     atomic_int   virge_busy;
+    atomic_uint  virge_irq_req;
 
     uint8_t      subsys_stat;
     uint8_t      subsys_cntl;
@@ -373,6 +374,9 @@ typedef struct virge_t {
     uint32_t     dma_mmio_addr;
     uint32_t     dma_data_type;
 
+    pc_timer_t   wake_timer;
+    pc_timer_t   irq_timer;
+
     int          pci;
     int          is_agp;
 } virge_t;
@@ -383,6 +387,28 @@ wake_fifo_thread(virge_t *virge) {
     thread_set_event(virge->wake_fifo_thread);
 }
 
+void
+s3_virge_wake_fifo_timer(void* priv)
+{
+    virge_t *virge = (virge_t *) priv;
+
+    thread_set_event(virge->wake_fifo_thread); /*Wake up FIFO thread if moving from idle*/
+}
+
+void
+s3_virge_wake_fifo_thread(virge_t *virge)
+{
+    if (!timer_is_enabled(&virge->wake_timer)) {
+        /*Don't wake FIFO thread immediately - if we do that it will probably
+          process one word and go back to sleep, requiring it to be woken on
+          almost every write. Instead, wait a short while so that the CPU
+          emulation writes more data so we have more batched-up work.*/
+        timer_on_auto(&virge->wake_timer, 100.0);
+    }
+    if (!timer_is_enabled(&virge->irq_timer))
+        timer_on_auto(&virge->irq_timer, 100.0);
+}
+
 static virge_t         *reset_state = NULL;
 
 static video_timings_t timing_diamond_stealth3d_2000_pci = { .type = VIDEO_PCI, .write_b = 2, .write_w = 2, .write_l = 3, .read_b = 28, .read_w = 28, .read_l = 45 };
@@ -471,6 +497,19 @@ s3_virge_update_irqs(virge_t *virge)
         pci_clear_irq(virge->pci_slot, PCI_INTA, &virge->irq_state);
 }
 
+void
+s3_virge_update_irq_timer(void* priv)
+{
+    virge_t *virge = (virge_t *) priv;
+
+    if (virge->virge_irq_req) {
+        virge->virge_irq_req--;
+        s3_virge_update_irqs(virge);
+    }
+
+    timer_on_auto(&virge->irq_timer, 100.);
+}
+
 static void
 s3_virge_out(uint16_t addr, uint8_t val, void *priv)
 {
@@ -1101,6 +1140,9 @@ static void
 s3_virge_vblank_start(svga_t *svga) {
     virge_t *virge = (virge_t *) svga->priv;
 
+    if (virge->virge_irq_req)
+        virge->virge_irq_req--;
+
     virge->subsys_stat |= INT_VSY;
     s3_virge_update_irqs(virge);
 }
@@ -1795,7 +1837,8 @@ fifo_thread(void *param)
          if (virge->cmd_dma)
             virge->subsys_stat |= (INT_HOST_DONE | INT_CMD_DONE);
 
-         s3_virge_update_irqs(virge);
+         //s3_virge_update_irqs(virge);
+         virge->virge_irq_req++;
     }
 }
 
@@ -1835,10 +1878,8 @@ s3_virge_queue(virge_t *virge, uint32_t addr, uint32_t val, uint32_t type)
 
     virge->fifo_write_idx++;
 
-    if (FIFO_ENTRIES > 0xe000)
-        wake_fifo_thread(virge);
-    if (FIFO_ENTRIES > 0xe000 || FIFO_ENTRIES < 8)
-        wake_fifo_thread(virge);
+    if (FIFO_ENTRIES > 0xe000 || FIFO_ENTRIES < 16)
+        s3_virge_wake_fifo_thread(virge);
 }
 
 static void
@@ -3642,7 +3683,8 @@ render_thread(void *param)
         }
         virge->s3d_busy = 0;
         virge->subsys_stat |= INT_S3D_DONE;
-        s3_virge_update_irqs(virge);
+        //s3_virge_update_irqs(virge);
+        virge->virge_irq_req++;
     }
 }
 
@@ -4571,6 +4613,9 @@ s3_virge_init(const device_t *info)
     virge->fifo_not_full_event = thread_create_event();
     virge->fifo_thread = thread_create(fifo_thread, virge);
 
+    timer_add(&virge->wake_timer, s3_virge_wake_fifo_timer, virge, 0);
+    timer_add(&virge->irq_timer, s3_virge_update_irq_timer, virge, 0);
+
     virge->local = info->local;
 
     *reset_state = *virge;