Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932105AbVLSOpX (ORCPT ); Mon, 19 Dec 2005 09:45:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932117AbVLSOpX (ORCPT ); Mon, 19 Dec 2005 09:45:23 -0500 Received: from moutvdom.kundenserver.de ([212.227.126.249]:63732 "EHLO moutvdomng.kundenserver.de") by vger.kernel.org with ESMTP id S932105AbVLSOpV (ORCPT ); Mon, 19 Dec 2005 09:45:21 -0500 Message-ID: <43A6C780.5070000@anagramm.de> Date: Mon, 19 Dec 2005 15:45:20 +0100 From: Clemens Koller User-Agent: Mozilla Thunderbird 1.0.2 (Windows/20050317) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Bartlomiej Zolnierkiewicz CC: linux-kernel@vger.kernel.org Subject: Re: IDE: PDC20275 turning on/off DMA dangerous? References: <43A2DE5F.7060108@anagramm.de> <58cb370e0512190440p3889a489sbc82f0c482fd9db9@mail.gmail.com> In-Reply-To: <58cb370e0512190440p3889a489sbc82f0c482fd9db9@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2584 Lines: 80 Hello, Bartolmiej! >>I am working on an embedded ppc (mpc8540) using a pretty common Promise IDE >>PCI controller w/ a PDC20275 on it (it's called Ultra TX2). >>I have an otherwise good Maxtor 6B120P0 (160GB) connected to it. >> >>But sometimes (expecially with more than zero disk-i/o-load), when I >>turn on DMA by >> >>$hdparm -X69 -d1 /dev/hda >>I get >> >>hda: task_out_intr: status=0x58 { DriveReady SeekComplete DataRequest } >>ide: failed opcode was: unknown >>hda: CHECK for good STATUS >> >>And when I turn off DMA with >>$hdparm -d0 /dev/hda >>I get sometimes a >> >>hda: DMA disabled >> >>which is fine but sometimes I also get: >> >>hda: status error: status=0x58 { DriveReady SeekComplete DataRequest } >>ide: failed opcode was: unknown >>hda: drive not ready for command >>hda: CHECK for good STATUS >> >>which is not so nice. >>Can you tell me if this is dangerous? > > > Is there any particular reason why you are using hdparm with '-d' and '-X'? I want to test it with DMA before fixing it into the kernel. > Your IDE host driver (pdc202xx_new in this case) should configure > best xfer mode and enable DMA so you shouldn't need to use hdparm. I didn't enable automatic turning on of DMA it in the kernel by default in the past because I had problems with this hdd controller and interrupts (some PCI IRQ mapping issues). The interrupt issues are solved now, so I've tried to enable DMA. DMA works pretty fine, I was just worried about the severity of the message. It doesn't really tell anything useful for non-ide-hackers. (whether it's dangerous or not.) > Given that IDE driver code for changing xfer mode and DMA setting > is racy and actually quite hard to fix, it will probably be removed in > the future (after auditing IDE host drivers). So, I guess the answer is: DMA itself seems to work and it isn't really dangerous - it's working as it's supposed to. But if you do it the way you do, you can run into problems due to races. Right? So, if I enable DMA as usual in the kernel, I don't usually risk my data?! > BTW please use linux-ide@vger.kernel.org for IDE problems Okay, in next thread. Thanks, -- Clemens Koller _______________________________ R&D Imaging Devices Anagramm GmbH Rupert-Mayer-Str. 45/1 81379 Muenchen Germany http://www.anagramm.de Phone: +49-89-741518-50 Fax: +49-89-741518-19 - 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/