From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner Subject: Re: 2.6.31-rt11 freeze on userland start on ARM Date: Wed, 30 Sep 2009 14:57:25 +0200 (CEST) Message-ID: References: <3efb10970909211136g4e74c8b3vc339d548cdd0959f@mail.gmail.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: linux-rt-users , LKML To: Remy Bohmer Return-path: Received: from www.tglx.de ([62.245.132.106]:54399 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752764AbZI3M6Z (ORCPT ); Wed, 30 Sep 2009 08:58:25 -0400 In-Reply-To: <3efb10970909211136g4e74c8b3vc339d548cdd0959f@mail.gmail.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On Mon, 21 Sep 2009, Remy Bohmer wrote: > So, as workaround/test I made this change: > > Index: linux-2.6.31/drivers/serial/atmel_serial.c > =================================================================== > --- linux-2.6.31.orig/drivers/serial/atmel_serial.c 2009-09-21 > 19:44:48.000000000 +0200 > +++ linux-2.6.31/drivers/serial/atmel_serial.c 2009-09-21 > 19:45:15.000000000 +0200 > @@ -808,7 +808,8 @@ static int atmel_startup(struct uart_por > /* > * Allocate the IRQ > */ > - retval = request_irq(port->irq, atmel_interrupt, IRQF_SHARED, > + retval = request_irq(port->irq, atmel_interrupt, > + IRQF_SHARED | IRQF_NODELAY, > tty ? tty->name : "atmel_serial", port); > if (retval) { > printk("atmel_serial: atmel_startup - Can't get irq\n"); The serial irq cannot run in hard irq context. There are two solutions to this problem: 1) Use the other timer which is available on AT91. 2) Make the serial driver explicitely threaded and check in the hardirq handler whether the irq originated from the serial driver. If yes, disable it in the serial device and return IRQ_WAKE_THREAD otherwise return IRQ_NONE. Thanks, tglx