On Fri, Jul 10, 2020 at 01:55:29PM +0100, Jon Hunter wrote: > Following this change, I have noticed that several debugfs entries can > no longer be read on some Tegra platforms. For example ... > > $ sudo cat /sys/kernel/debug/usb/xhci/3530000.usb/event-ring/cycle > cat: /sys/kernel/debug/usb/xhci/3530000.usb/event-ring/cycle: Invalid > argument > > $ sudo cat /sys/kernel/debug/emc/available_rates > > > cat: /sys/kernel/debug/emc/available_rates: Invalid argument > > $ sudo cat /sys/kernel/debug/bpmp/debug/proc/testint > cat: /sys/kernel/debug/bpmp/debug/proc/testint: Invalid argument > > $ sudo cat /sys/kernel/debug/pcie/ports > > > cat: /sys/kernel/debug/pcie/ports: Invalid argument > > I have reverted the above drivers to use seq_read() instead of > seq_read_iter() and they work again. Have you seen any problems with this? I haven't seen any of that. But some of these files should also exist on x86, so let me try to reproduce it.