Hi Laurentiu, > I took your code, added the missing mapping and placed it in a patch. > Please see attached (compile tested only). Thanks! Unfortunately, the OHCI fails with errors such as usb 1-1: device descriptor read/64, error -12 that I tracked down to the calls hub_port_init -> usb_control_msg -> usb_internal_control_msg -> usb_start_wait_urb -> usb_submit_urb -> usb_hcd_submit_urb -> hcd->driver->urb_enqueue -> ohci_urb_enqueue -> ed_get -> ed_alloc -> dma_pool_zalloc -> dma_pool_alloc -> pool_alloc_page, which returns NULL. Then I noticed /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */ that might be a problem considering that the HCD handles pool memory in IRQ handlers, for instance: do_IRQ -> generic_handle_irq -> handle_level_irq -> handle_irq_event -> handle_irq_event_percpu -> __handle_irq_event_percpu -> usb_hcd_irq -> ohci_irq -> ohci_work -> finish_urb -> __usb_hcd_giveback_urb -> usb_hcd_unmap_urb_for_dma -> hcd_buffer_free Also, DMA_BUFFER_SIZE in ohci-ps2.c is only 256 KiB in total. Is the new pool implementation at least as efficient as the previous one? Fredrik
