From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hurley Subject: Re: What to set uart_port->irq to for polled driver? Date: Thu, 28 Feb 2013 15:16:33 -0500 Message-ID: <1362082593.3337.16.camel@thor.lan> References: <1362076338.3337.3.camel@thor.lan> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mailout02.c08.mtsvc.net ([205.186.168.190]:58550 "EHLO mailout02.c08.mtsvc.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759169Ab3B1UQg (ORCPT ); Thu, 28 Feb 2013 15:16:36 -0500 In-Reply-To: Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Grant Edwards Cc: linux-serial@vger.kernel.org On Thu, 2013-02-28 at 18:43 +0000, Grant Edwards wrote: > On 2013-02-28, Peter Hurley wrote: > > On Wed, 2013-02-13 at 15:24 +0000, Grant Edwards wrote: > >> For a polled serial driver that doesn't use interrupts, to what should > >> the "irq" field in the uart_port structure be set? Should it be 0? > >> Should it be the unused IRQ associated with the PCI card slot in which > >> the board is found? > > > > Doesn't look supported, but adding the support doesn't look difficult. > > At the very least, a patch is required so that on port shutdown, the > > core doesn't synchronize_irq(). > > Does the call ty synchronize_irq() do any harm? AFAICT, it will just > cause a short delay if handling of that IRQ is in-progress. > > I currently set the "irq" field to the IRQ number that would be used > by the board if I did choose to enable interrupts. That seems to work > fine (with rather limited testing). AFAICT, it's probably ok; but it might not be. Certainly more robust to just add a UPF_POLLING flag and skip the synchronize_irq(). Is this an in-tree driver? Regards, Peter Hurley