Kernel/USB: Ignore shared IRQs

According the USB spec/UHCI datasheet (as well as the Linux and BSD source code), if we receive an IRQ and USBSTS is 0, then the IRQ does not belong to us and we should immediately jump out of the handler.
Author: https://github.com/Quaker762 Commit: https://github.com/SerenityOS/serenity/commit/ff4afe17bee Pull-request: https://github.com/SerenityOS/serenity/pull/4019 Reviewed-by: https://github.com/Lubrsi Reviewed-by: https://github.com/awesomekling
2021-01-03 16:01:52 +11:00 · 2021-01-03 16:01:52 +11:00 · ff4afe17be · 2024-07-19 00:00:47 +09:00
commit ff4afe17be
parent 770a729e59
1 changed files with 4 additions and 0 deletions
--- a/Kernel/Devices/USB/UHCIController.cpp
+++ b/Kernel/Devices/USB/UHCIController.cpp
@ -395,6 +395,10 @@ void UHCIController::spawn_port_proc()

 void UHCIController::handle_irq(const RegisterState&)
 {
+    // Shared IRQ. Not ours!
+    if(!read_usbsts())
+        return;
+
    klog() << "UHCI: Interrupt happened!";
    klog() << "Value of USBSTS: " << read_usbsts();
 }