From 865aade42b4f4db9362fe3e10abc9d1eb8f39403 Mon Sep 17 00:00:00 2001
From: Liav A <liavalb@gmail.com>
Date: Fri, 5 Feb 2021 06:51:47 +0200
Subject: [PATCH] Kernel: Clear pending interrupts before enabling IRQs of IDE
 Channel

Calling detect_disks() can generate interrupts, so we must clear it to
allow proper function when booting with kernel argument smp=on.
---
 Kernel/Storage/IDEChannel.cpp | 8 ++++++++
 Kernel/Storage/IDEChannel.h   | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/Kernel/Storage/IDEChannel.cpp b/Kernel/Storage/IDEChannel.cpp
index e7dc66846c1..7d18c662e05 100644
--- a/Kernel/Storage/IDEChannel.cpp
+++ b/Kernel/Storage/IDEChannel.cpp
@@ -142,9 +142,17 @@ IDEChannel::IDEChannel(const IDEController& controller, IOAddressGroup io_group,
 
     initialize(force_pio);
     detect_disks();
+
+    // Note: calling to detect_disks could generate an interrupt, clear it if that's the case
+    clear_pending_interrupts();
     enable_irq();
 }
 
+void IDEChannel::clear_pending_interrupts() const
+{
+    m_io_group.io_base().offset(ATA_REG_STATUS).in<u8>();
+}
+
 IDEChannel::~IDEChannel()
 {
 }
diff --git a/Kernel/Storage/IDEChannel.h b/Kernel/Storage/IDEChannel.h
index edf60473f88..1380ca364ef 100644
--- a/Kernel/Storage/IDEChannel.h
+++ b/Kernel/Storage/IDEChannel.h
@@ -138,6 +138,8 @@ private:
     void start_request(AsyncBlockDeviceRequest&, bool, bool, u16);
     void complete_current_request(AsyncDeviceRequest::RequestResult);
 
+    void clear_pending_interrupts() const;
+
     void ata_access(Direction, bool, u32, u8, u16, bool);
     void ata_read_sectors_with_dma(bool, u16);
     void ata_read_sectors(bool, u16);