From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e6.ny.us.ibm.com (e6.ny.us.ibm.com [32.97.182.146]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e6.ny.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 98286B6F99 for ; Thu, 16 Jun 2011 05:18:14 +1000 (EST) Received: from d01relay05.pok.ibm.com (d01relay05.pok.ibm.com [9.56.227.237]) by e6.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id p5FIs1Cv022974 for ; Wed, 15 Jun 2011 14:54:01 -0400 Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d01relay05.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p5FJI9I1051488 for ; Wed, 15 Jun 2011 15:18:09 -0400 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p5FDHtwf027335 for ; Wed, 15 Jun 2011 07:17:55 -0600 Date: Wed, 15 Jun 2011 12:17:47 -0700 From: Nishanth Aravamudan To: jgarzik@pobox.com Subject: libata/ipr/powerpc: regression between 2.6.39-rc4 and 2.6.39-rc5 Message-ID: <20110615191747.GA6324@us.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: wayneb@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, tj@kernel.org, mbizon@freebox.fr, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Jeff, It appears that commit 7b3a24c57d2eeda8dba9c205342b12689c4679f9 broke CD-ROMs on the IPR SATA bus on powerpc machines: ata_port_alloc: ENTER ata_port_probe: ata1: bus probe begin ata1.00: ata_dev_read_id: ENTER ata1.00: failed to IDENTIFY (I/O error, err_mask=0x40) ata1.00: ata_dev_read_id: ENTER ata1.00: failed to IDENTIFY (I/O error, err_mask=0x40) ata1.00: limiting speed to UDMA7:PIO5 ata1.00: ata_dev_read_id: ENTER ata1.00: failed to IDENTIFY (I/O error, err_mask=0x40) ata1.00: disabled ata_port_probe: ata1: bus probe end scsi_alloc_sdev: Allocation failure during SCSI scanning, some SCSI devices might not be configured The commit in question is tagged as AHCI, but does touch the libata core. I'm not well-versed with this code, but here's what I think I know :) >>From __scsi_add_device, we first allocate the target: scsi_alloc_target -> shost->hostt->target_alloc -> ipr_target_alloc -> ata_port_alloc -> sets FROZEN We error out when we allocate the sdev: scsi_alloc_sdev -> shost->hostt->slave_alloc -> ipr_slave_alloc -> ipr_ata_slave_alloc -> ata_sas_port_init -> ata_port_probe >>From what I can tell, the only place that explicitly clears the FROZEN flag is the error-handling code via ata_eh_thaw_port(). So I thought either we're not invoking the error-handler at probe time correctly to kick the port or perhaps the SAS code is not clearing the flag? I tried the following patch: diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c index d51f979..abd0e0b 100644 --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -3797,6 +3797,7 @@ EXPORT_SYMBOL_GPL(ata_sas_port_alloc); */ int ata_sas_port_start(struct ata_port *ap) { + ap->pflags &= ~ATA_PFLAG_FROZEN; return 0; } EXPORT_SYMBOL_GPL(ata_sas_port_start); and the CD-ROM drive works, but I have no idea if it's the right thing to do. I chose this particular change, FWIW, because we call ata_sas_port_start before we probe in ata_sas_port_init and it seems like we need to mark the port as not frozen before we init it? Perhaps that should really be a call to a thaw function, not sure. Let's just say the ATA/SAS/SCSI interactions are a bit hard to follow at first :) Any insight you can provide would be great! Thanks, Nish -- Nishanth Aravamudan IBM Linux Technology Center