Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 10 Oct 2001 17:03:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 10 Oct 2001 17:03:30 -0400 Received: from asterix.hrz.tu-chemnitz.de ([134.109.132.84]:58576 "EHLO asterix.hrz.tu-chemnitz.de") by vger.kernel.org with ESMTP id ; Wed, 10 Oct 2001 17:03:17 -0400 Subject: Re: Changes to ide-cd for 2.4.1 are broken? Date: 10 Oct 2001 23:03:43 +0200 Organization: Chemnitz University of Technology Lines: 110 Message-ID: <87het7b428.fsf@kosh.ultra.csn.tu-chemnitz.de> In-Reply-To: <001801c09e3a$4a189270$653b090a@sulaco> <008401c0f20f$4458dec0$643b090a@sulaco> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="=-=-=" User-Agent: Gnus/5.0808 (Gnus v5.8.8) XEmacs/21.4 (Artificial Intelligence) To: linux-kernel@vger.kernel.org From: Enrico Scholz Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= [ This is a very old thread; please see [1] for a complete list and [2] for technical details ] johnsom@home.com ("Michael Johnson") writes: > So, the patch you are proposing will always consider the tray open, > even if it is closed. Why do you need this behavior? I need the behavior to close the tray when it is open. Currently it will never by closed. > Why is checking CDS_TRAY_OPEN, to see if the tray is open, broken? CDS_TRAY_OPEN will never be returned; only CDS_NO_DISC. > The code in cdrom.c looks fine to me. The code there is fine. The code in ide-cd.c is broken: | if (sense.asc == 0x3a && (!sense.ascq||sense.ascq == 1)) | return CDS_NO_DISC; | else | return CDS_TRAY_OPEN; Assuming the tray is open. Then ATAPI IDE-CD drives will have an unspecified ASCQ -- which is mostly zero (see ATAPI specification). Therefore, it will be returned CDS_NO_DISC. This is wrong; the correct result should be CDS_TRAY_OPEN because it is a more special description of the state than CDS_NO_DISC and the layers above are trusting in this value. CDS_NO_DISC would lead to an immediate error in the open_for_data() function in cdrom.c, but CDS_TRAY_OPEN makes it possible to close the tray automatically. This can be demonstrated by: | [kernel <2.4.1; open tray] | $ rmmod cdrom | $ modprobe cdrom autoclose=1 | $ mount /cdrom | ... tray will be closed and the CD mounted ... | $ | | [kernel >=2.4.1; open tray] | $ rmmod cdrom | $ modprobe cdrom autoclose=0 | $ mount /cdrom | mount: No medium found | $ As you can see, the current behavior makes the 'autoclose' option effectless on "normal" IDE-CDROMs. Only special CDROMs following the Mt Fuji standard can profit from the ASCQ test. I suggest the patch already given in [3] and will append it again. > > Hi all, this is an old thread. It was started because the return > > value from cd info was changed in 2.4.1 in the case when the tray > > might be open or there simply be no disc in the drive for an IDE > > CD-ROM. > > [...] > > > > >Right, old ATAPI has 3a/02 as the only possible condition, so > > > > >we can't really tell between no disc and tray open. I guess the > > > > >safest is to just keep the old behaviour for !ascq and report > > > > >open. > > > > > > > I don't understand why the current(2.4.1) behavior is a problem... > > > > Unfortunately changing the return code means that the generic cdrom.c > > code is broekn, in particular [...] to close when attempted to be > > mounted. Enrico Footnotes: [1] http://marc.theaimsgroup.com/?t=98244733600003&w=2&r=1 [2] http://marc.theaimsgroup.com/?l=linux-kernel&m=98252992732626&w=2 [3] http://marc.theaimsgroup.com/?l=linux-kernel&m=98244720319144&w=2 --=-=-= Content-Type: text/x-patch Content-Disposition: attachment; filename=patch-cdrom.diff --- linux/drivers/ide/ide-cd.c.orig Tue May 29 11:24:24 2001 +++ linux/drivers/ide/ide-cd.c Tue May 29 11:25:44 2001 @@ -2319,10 +2319,7 @@ * any other way to detect this... */ if (sense.sense_key == NOT_READY) { - if (sense.asc == 0x3a && (!sense.ascq||sense.ascq == 1)) - return CDS_NO_DISC; - else - return CDS_TRAY_OPEN; + if (sense.asc == 0x3a) return CDS_TRAY_OPEN; } return CDS_DRIVE_NOT_READY; --=-=-=-- - 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/