Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758548AbWK0UBm (ORCPT ); Mon, 27 Nov 2006 15:01:42 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758547AbWK0UBm (ORCPT ); Mon, 27 Nov 2006 15:01:42 -0500 Received: from outbound-cpk.frontbridge.com ([207.46.163.16]:16944 "EHLO outbound1-cpk-R.bigfish.com") by vger.kernel.org with ESMTP id S1758548AbWK0UBl (ORCPT ); Mon, 27 Nov 2006 15:01:41 -0500 X-BigFish: VP X-Server-Uuid: 89466532-923C-4A88-82C1-66ACAA0041DF Date: Mon, 27 Nov 2006 13:04:21 -0700 From: "Jordan Crouse" To: "Alan" cc: linux-kernel@vger.kernel.org, info-linux@ldcmail.amd.com Subject: Re: char: Add MFGPT driver for the CS5535/CS5536 Message-ID: <20061127200421.GB4495@cosmic.amd.com> References: <20061122205736.GA588@cosmic.amd.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.5.11 X-OriginalArrivalTime: 27 Nov 2006 19:58:22.0916 (UTC) FILETIME=[64B50840:01C7125E] X-WSS-ID: 69759CD41WC1545491-01-01 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2073 Lines: 50 On 22/11/06 22:17 +0000, Alan wrote: > > The attached driver provides a low-level interface to the block, and > > allows for other kernel drivers to use the timers. > > Three comments > > 2. There is an RTC timer interface - could you use that interface > for some of this so its compatible and consistent ? Do you mean, use the RTC interface itself (i.e. - turn the mfgpt driver into an RTC driver), or just emulate parts of the RTC interface in the MFGPT driver. I would be fine with the second option - the first doesn't really fit, since the only functionality the RTC and the MFGPT share is the periodic interrupt feature (which is sub-optimal on RTC anyway). If the "timer interrupt" feature feels tacked on, thats because it is. The best use for the MFGPT block is to drive a duty cycle on the output pin suitable for LEDs and such. Most Geode customers would use it for that purpose. Running a close second on the usefulness scale is the watchdog timer - its always nice to have that sort of functionality available at the hardware level (and its a double bonus that the watchdog can be set up to continue running while in suspend). The interrupt/NMI functionality was added to the hardware for the BIOS to use, and we added it to the kernel driver for a sense of completeness. I personally can't fathom anybody using the timers, and I would gladly remove them if nobody else can come up with a realistic usage model. > 3. Ditto for a watchdog use - although that would be a separate > driver using the kernel hooks anyway. That was the plan - I do have a watchdog driver that I had when I first wrote the MFGPT driver for a now defunct project. I should dust it off and add it in. Thanks, Jordan -- Jordan Crouse Senior Linux Engineer Advanced Micro Devices, Inc. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/