On 19.2.2020 1.50, Ajay Gupta wrote: > From: Ajay Gupta <ajayg@xxxxxxxxxx> > > Xhci interrupt must be enabled only after controller is > initialized and started. Currently interrupt is enabled > first in xhci_run() and later hcd state is set to running > in xhci_run_finished(). > > On a slow system (such as FPGA based platform) the time > difference between enabling interrupt and setting the hcd > state becomes huge enough where interrupt is triggered but > controller initialization is not complete yet. > > Fixing the same by moving the interrupt enable (CMD_EIE) > part of code snippet from xhci_run() to xhci_run_finished(). > > Signed-off-by: Ajay Gupta <ajayg@xxxxxxxxxx> > --- Sounds reasonable, but xHCI specs wants interrupts set and enabled before xHC is running state. I see this can be an issue if we get a port event for a USB 3 port before the USB3 hcd is added. What kind of issues did you see? I'd guess NULL pointer dereference in handle_port_status()?. We could move interrupt enabling to xhci_run_finished() before xhci_start() is called, then the USB3 hcd should be initialized before we receive interrupts. Does that work for you? Details: xHCI section 4.2 "Host Controller Initialization" has the following sequence: - Enable host system interrupt (CMD_EIE), - Enable primary interupter (set IE bit in IMAN register) - set run bit in USBCMD register. And section 5.5.2 has a note: "All registers of the Primary Interrupter shall be initialized before setting the Run/Stop (RS) flag in the USBCMD register to ‘1’." -Mathias
