Changes between Version 5 and Version 6 of venice/PCIe

Timestamp:

01/29/2024 07:51:25 PM (10 months ago)

Author:

Ryan Erbstoesser

Comment:

add msi note

venice/PCIe

@@ -65 +65 @@
 It is recommended to adjust this GPIO in the bootloader and not when the board boots into Linux. If the GPIO state does not persist across reboots, then add the command to the extra variable. 
 
+= MSI Notes
+Some devices/drivers require MSI interrupts and some require legacy interrupts (ath9k radio devices come to mind which require legacy interrupts). 
+
+The Designware PCIe core (used on IMX6/IMX8M) works as such as soon as any MSI interrupt is enabled, the core no longer forwards legacy IRQs so if any card in your system needs legacy interrupts you need to disable MSI with {{{pci=nomsi}}} in uboot:
+{{{
+setenv extra 'pci=nomsi'
+saveenv
+reset
+}}}
+ * Note: (https://patchwork.kernel.org/project/linux-pci/patch/20181120165626.26424-2-stefan@agner.ch/#22345435).
+
+If you have a PCIe card that requires legacy interrupts you can use 'pci=nomsi' but this means you will not be able to use any card that 'requires' MSI (ath11k radio devices come to mind). Enable it if you need to to make your system work.