On 4/24/24 15:30, Alan Stern wrote:
On Wed, Apr 24, 2024 at 12:59:51PM -0700, Guenter Roeck wrote:Testing ohci functionality with qemu's pci-ohci emulation often results in ohci interface stalls, resulting in hung task timeouts. The problem is caused by lost interrupts between the emulation and the Linux kernel code. Additional interrupts raised while the ohci interrupt handler in Linux is running and before the handler clears the interrupt status are not handled. The fix for a similar problem in ehci suggests that the problem is likely caused by edge-triggered MSI interrupts. See commit 0b60557230ad ("usb: ehci: Prevent missed ehci interrupts with edge-triggered MSI") for details. Ensure that the ohci interrupt code handles all pending interrupts before returning to solve the problem. Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx> Fixes: 306c54d0edb6 ("usb: hcd: Try MSI interrupts on PCI devices") Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx> --- v2: Only repeat if the interface is still activeReviewed-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Greg might insist that the patch be CC'ed to stable@xxxxxxxxxxxxxxx since it contains a Fixes: tag.
Sure, I'll be happy to send v3 and add it if he wants me to do that. I never know if I should add it myself or if this is supposed to be a maintainer privilege. Thanks, Guenter
