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Kernel: Drain I8042 PS/2 keyboard output after enabling

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As soon as we enable the first PS/2 port on the I8042 controller, the
output buffer may become full. We need to drain it before attempting
any new commands with the controller (such as enabling the second PS/2
port).

Fixes #10872.
This commit is contained in:
Jelle Raaijmakers 2021-11-12 00:17:30 +01:00 • committed by Andreas Kling
parent 5e3fe52fc4
commit 86a1ff5204
2 changed files with 7 additions and 6 deletions
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11
Kernel/Devices/HID/I8042Controller.cpp
View file

@ -36,13 +36,12 @@ UNMAP_AFTER_INIT void I8042Controller::detect_devices()
u8 configuration;
{
SpinlockLocker lock(m_lock);
// Disable devices
drain_output_buffer();
do_wait_then_write(I8042Port::Command, I8042Command::DisableFirstPS2Port);
do_wait_then_write(I8042Port::Command, I8042Command::DisableSecondPS2Port); // ignored if it doesn't exist
// Drain buffers
do_drain();
do_wait_then_write(I8042Port::Command, I8042Command::ReadConfiguration);
configuration = do_wait_then_read(I8042Port::Buffer);
do_wait_then_write(I8042Port::Command, I8042Command::WriteConfiguration);
@ -75,6 +74,8 @@ UNMAP_AFTER_INIT void I8042Controller::detect_devices()
dbgln("I8042: Keyboard port not available");
}
drain_output_buffer();
if (m_is_dual_channel) {
do_wait_then_write(I8042Port::Command, I8042Command::TestSecondPS2Port);
m_second_port_available = (do_wait_then_read(I8042Port::Buffer) == 0);
@ -152,7 +153,7 @@ bool I8042Controller::irq_process_input_buffer(HIDDevice::Type instrument_type)
return false;
}
void I8042Controller::do_drain()
void I8042Controller::drain_output_buffer()
{
for (;;) {
u8 status = IO::in8(I8042Port::Status);