From 0b3a8687299fddb65ab6c1966ad82dde8fa26187 Mon Sep 17 00:00:00 2001
From: Conrad Pankoff <deoxxa@fknsrs.biz>
Date: Fri, 27 Dec 2019 08:57:58 +1100
Subject: [PATCH] Kernel: Simplify force_pio logic in PATA driver (#923)

---
 Kernel/Devices/PATAChannel.cpp    | 28 ++++++++++++++++------------
 Kernel/Devices/PATAChannel.h      |  1 -
 Kernel/Devices/PATADiskDevice.cpp |  2 +-
 3 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/Kernel/Devices/PATAChannel.cpp b/Kernel/Devices/PATAChannel.cpp
index 1085e1f10fa..6866139e060 100644
--- a/Kernel/Devices/PATAChannel.cpp
+++ b/Kernel/Devices/PATAChannel.cpp
@@ -118,19 +118,23 @@ void PATAChannel::initialize(bool force_pio)
             kprintf("PATAChannel: PATA Controller found! id=%w:%w\n", id.vendor_id, id.device_id);
         }
     });
-    m_force_pio.resource() = false;
-    if (!m_pci_address.is_null()) {
-        // Let's try to set up DMA transfers.
-        PCI::enable_bus_mastering(m_pci_address);
-        m_prdt.end_of_table = 0x8000;
-        m_bus_master_base = PCI::get_BAR4(m_pci_address) & 0xfffc;
-        m_dma_buffer_page = MM.allocate_supervisor_physical_page();
-        kprintf("PATAChannel: Bus master IDE: I/O @ %x\n", m_bus_master_base);
-        if (force_pio) {
-            m_force_pio.resource() = true;
-            kprintf("PATAChannel: Requested to force PIO mode!\n");
-        }
+
+    if (m_pci_address.is_null()) {
+        kprintf("PATAChannel: PCI address was null; can not set up DMA\n");
+        return;
     }
+
+    if (force_pio) {
+        kprintf("PATAChannel: Requested to force PIO mode; not setting up DMA\n");
+        return;
+    }
+
+    // Let's try to set up DMA transfers.
+    PCI::enable_bus_mastering(m_pci_address);
+    m_prdt.end_of_table = 0x8000;
+    m_bus_master_base = PCI::get_BAR4(m_pci_address) & 0xfffc;
+    m_dma_buffer_page = MM.allocate_supervisor_physical_page();
+    kprintf("PATAChannel: Bus master IDE: I/O @ %x\n", m_bus_master_base);
 }
 
 static void print_ide_status(u8 status)
diff --git a/Kernel/Devices/PATAChannel.h b/Kernel/Devices/PATAChannel.h
index af93cf18374..da1cb954218 100644
--- a/Kernel/Devices/PATAChannel.h
+++ b/Kernel/Devices/PATAChannel.h
@@ -69,7 +69,6 @@ private:
     RefPtr<PhysicalPage> m_dma_buffer_page;
     u16 m_bus_master_base { 0 };
     Lockable<bool> m_dma_enabled;
-    Lockable<bool> m_force_pio;
 
     RefPtr<PATADiskDevice> m_master;
     RefPtr<PATADiskDevice> m_slave;
diff --git a/Kernel/Devices/PATADiskDevice.cpp b/Kernel/Devices/PATADiskDevice.cpp
index eadbb1957d4..8c017e5d7a0 100644
--- a/Kernel/Devices/PATADiskDevice.cpp
+++ b/Kernel/Devices/PATADiskDevice.cpp
@@ -24,7 +24,7 @@ const char* PATADiskDevice::class_name() const
 
 bool PATADiskDevice::read_blocks(unsigned index, u16 count, u8* out)
 {
-    if (m_channel.m_bus_master_base && m_channel.m_dma_enabled.resource() && !m_channel.m_force_pio.resource())
+    if (m_channel.m_bus_master_base && m_channel.m_dma_enabled.resource())
         return read_sectors_with_dma(index, count, out);
     return read_sectors(index, count, out);
 }