From 7126a42d4d2ceabfb8af5f13e055351b5d0abb33 Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Sun, 1 Dec 2019 12:53:19 +0100
Subject: [PATCH] Kernel: Use a WaitQueue in the SoundBlaster 16 driver

Instead of waking up to check for IRQ's regularly, use a WaitQueue and
wake it up in the IRQ handler.
---
 Kernel/Devices/SB16.cpp | 17 +++++++----------
 Kernel/Devices/SB16.h   |  4 +++-
 2 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/Kernel/Devices/SB16.cpp b/Kernel/Devices/SB16.cpp
index 0ec3b382450..e51ed079df3 100644
--- a/Kernel/Devices/SB16.cpp
+++ b/Kernel/Devices/SB16.cpp
@@ -65,6 +65,8 @@ SB16& SB16::the()
 
 void SB16::initialize()
 {
+    disable_irq();
+
     IO::out8(0x226, 1);
     IO::delay();
     IO::out8(0x226, 0);
@@ -81,7 +83,6 @@ void SB16::initialize()
     auto vmin = dsp_read();
 
     kprintf("SB16: found version %d.%d\n", m_major_version, vmin);
-    enable_irq();
 }
 
 bool SB16::can_read(const FileDescription&) const
@@ -134,16 +135,15 @@ void SB16::handle_irq()
     if (m_major_version >= 4)
         IO::in8(DSP_R_ACK); // 16 bit interrupt
 
-    m_interrupted = true;
+    m_irq_queue.wake_all();
 }
 
 void SB16::wait_for_irq()
 {
-    // Well, we have no way of knowing how much got written. So just hope all of
-    // it did, even if we're interrupted.
-    (void)current->block_until("Interrupting", [this] {
-        return m_interrupted;
-    });
+    cli();
+    enable_irq();
+    current->wait_on(m_irq_queue);
+    disable_irq();
 }
 
 ssize_t SB16::write(FileDescription&, const u8* data, ssize_t length)
@@ -162,7 +162,6 @@ ssize_t SB16::write(FileDescription&, const u8* data, ssize_t length)
 
     u8 mode = (u8)SampleFormat::Signed | (u8)SampleFormat::Stereo;
 
-    disable_irq();
     const int sample_rate = 44100;
     set_sample_rate(sample_rate);
     memcpy(m_dma_buffer_page->paddr().as_ptr(), data, length);
@@ -183,8 +182,6 @@ ssize_t SB16::write(FileDescription&, const u8* data, ssize_t length)
     dsp_write((u8)sample_count);
     dsp_write((u8)(sample_count >> 8));
 
-    m_interrupted = false;
-    enable_irq();
     wait_for_irq();
     return length;
 }
diff --git a/Kernel/Devices/SB16.h b/Kernel/Devices/SB16.h
index 63d54569b86..43d70d595e8 100644
--- a/Kernel/Devices/SB16.h
+++ b/Kernel/Devices/SB16.h
@@ -5,6 +5,7 @@
 #include <Kernel/IRQHandler.h>
 #include <Kernel/VM/PhysicalAddress.h>
 #include <Kernel/VM/PhysicalPage.h>
+#include <Kernel/WaitQueue.h>
 
 class SB16;
 
@@ -37,6 +38,7 @@ private:
     u8 dsp_read();
 
     RefPtr<PhysicalPage> m_dma_buffer_page;
-    bool m_interrupted { false };
     int m_major_version { 0 };
+
+    WaitQueue m_irq_queue;
 };