From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: something strange in libata-core.c for kernel 2.6.22-rc3 Date: Mon, 21 May 2007 11:09:03 +0200 Message-ID: <465161AF.6030002@gmail.com> References: <46515983.6030206@shaw.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from wr-out-0506.google.com ([64.233.184.231]:12755 "EHLO wr-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754375AbXEUJJ2 (ORCPT ); Mon, 21 May 2007 05:09:28 -0400 Received: by wr-out-0506.google.com with SMTP id 76so1315709wra for ; Mon, 21 May 2007 02:09:27 -0700 (PDT) In-Reply-To: <46515983.6030206@shaw.ca> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Robert Hancock Cc: linux-kernel , ide , l.genoni@oltrelinux.com, Alan Cox Robert Hancock wrote: >> Alan, did you have a chance to test the ACPI cable detection? It just >> didn't work when I tried it. It always returned 80c on my machine. > > On a whim I started poking around in the disassembled ACPI DSDT code for > my Asus A8N-SLI Deluxe board, which is one of these chipsets. The > original thought was that the STM/GTM trick on these chipsets is > supposed to allow us to determine what modes we should use based on what > modes it sets up appropriately. Unfortunately, unless I'm missing > something in the AML (which is possible) it doesn't seem like there is > any validation being done on the settings passed in. The settings appear > to essentially just get programmed into the controller when STM is > called and read back on GTM. Yeah, that's consistent to what I've seen on my machine which is a variant of A8N. No matter what value I through at _STM, _GTM just echoed the result thus always leading to 80c configuration. > I guess this means that what we have to do is trust that the BIOS set up > a reasonable mode and base the cable detect on that (either by reading > back the boot-up controller registers, or by calling GTM). I imagine > this is what the Windows default IDE driver is doing (just using the > boot-up mode and feeding it back using GTM/STM on suspend/resume cycles). Alan, what do you think? -- tejun