Date: Tue, 24 Apr 2007 18:58:43 +0200 From: Thomas Quinot <thomas@FreeBSD.ORG> To: Josh Carroll <josh.carroll@gmail.com> Cc: freebsd-scsi@freebsd.org, bug-followup@freebsd.org Subject: Re: kern/103602: drive gets wedged on READ CD CAPACITY if no disc is in Message-ID: <20070424165843.GD7087@melamine.cuivre.fr.eu.org> In-Reply-To: <8cb6106e0704240929j38178df6k1b6391446c69a2ae@mail.gmail.com> References: <8cb6106e0703261318o120c620ar6b2461802632fc01@mail.gmail.com> <8cb6106e0703262119g5a9afd4m2c3d5665c85c4969@mail.gmail.com> <4608A35E.3010404@samsco.org> <8cb6106e0703262157m7fd0ae96p3bb5368af797dc6b@mail.gmail.com> <460AA9E3.4030106@samsco.org> <8cb6106e0703281531k4c5bebecp5566c64c8f458a74@mail.gmail.com> <8cb6106e0704030039if46397fvfc993d9c9e19e1fc@mail.gmail.com> <8cb6106e0704032107w457026b1t1e04ed11008af48a@mail.gmail.com> <20070424162008.GA7087@melamine.cuivre.fr.eu.org> <8cb6106e0704240929j38178df6k1b6391446c69a2ae@mail.gmail.com>
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--4SFOXa2GPu3tIq4H Content-Type: text/plain; charset=us-ascii Content-Disposition: inline * Josh Carroll, 2007-04-24 : > Here is my output (first with no disk, second with). I see sk=02 here as > well: > > % ./readcap /dev/acd0 > ioctl returned error 5 Input/output error > Sense data: error=70 sk=02 asc=3a ascq=00 > > % ./readcap /dev/acd0 > ioctl returned error 0 Unknown error: 0 > Sense data: error=00 sk=00 asc=00 ascq=00 > LBA of last sector in last session: 185805 > Sector size: 2048 It just occurred to me that there is one point that is different when using readcap, compared to sg_readcap+ATAPI/CAM: only in the latter case is DMA used. *And* you mentioned, very early in this PR, that disabling DMA altogether made the problem disappear. So, let's try something: enable DMA only for READ and WRITE commands (where it's most useful). Apparently it's not a completely unhead-of situation that some drives have problems with DMA for commands other than READ and WRITE, see: http://www.mail-archive.com/linux-ide@vger.kernel.org/msg05425.html Patch attached. Thomas. --4SFOXa2GPu3tIq4H Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=d Index: sys/dev/ata/atapi-cam.c =================================================================== RCS file: /space/mirror/ncvs/src/sys/dev/ata/atapi-cam.c,v retrieving revision 1.50 diff -u -r1.50 atapi-cam.c --- sys/dev/ata/atapi-cam.c 14 Mar 2007 01:59:00 -0000 1.50 +++ sys/dev/ata/atapi-cam.c 24 Apr 2007 16:57:11 -0000 @@ -516,10 +516,10 @@ switch (ccb_h->flags & CAM_DIR_MASK) { case CAM_DIR_IN: - request_flags |= ATA_R_READ|ATA_R_DMA; + request_flags |= ATA_R_READ; break; case CAM_DIR_OUT: - request_flags |= ATA_R_WRITE|ATA_R_DMA; + request_flags |= ATA_R_WRITE; break; case CAM_DIR_NONE: /* No flags need to be set */ @@ -528,8 +528,6 @@ device_printf(softc->dev, "unknown IO operation\n"); goto action_invalid; } - if (softc->atadev[tid]->mode < ATA_DMA) - request_flags &= ~ATA_R_DMA; if ((hcb = allocate_hcb(softc, unit, bus, ccb)) == NULL) { printf("cannot allocate ATAPI/CAM hcb\n"); @@ -594,7 +592,23 @@ request->u.atapi.ccb[3] = request->u.atapi.ccb[1] & 0x1f; request->u.atapi.ccb[2] = 0; request->u.atapi.ccb[1] = 0; + + case READ_10: + /* FALLTHROUGH */ + case WRITE_10: + /* FALLTHROUGH */ + case READ_12: + /* FALLTHROUGH */ + case WRITE_12: + /* + * Enable DMA (if target supports it) for READ and WRITE commands + * only, as some combinations of drive, controller and chipset do + * not behave correctly when DMA is enabled for other commands. + */ + if (softc->atadev[tid]->mode >= ATA_DMA) + request_flags |= ATA_R_DMA; break; + } if ((ccb_h->flags & CAM_DIR_MASK) == CAM_DIR_IN && (len & 1)) { @@ -616,7 +630,7 @@ /* * no retries are to be performed at the ATA level; any retries - * will be done by CAM . + * will be done by CAM. */ request->retries = 0; --4SFOXa2GPu3tIq4H--
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