Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754192AbaG3MYv (ORCPT ); Wed, 30 Jul 2014 08:24:51 -0400 Received: from ip4-83-240-18-248.cust.nbox.cz ([83.240.18.248]:36775 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753001AbaG3MPd (ORCPT ); Wed, 30 Jul 2014 08:15:33 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Hao , Tejun Heo , Jiri Slaby Subject: [PATCH 3.12 81/94] libata: support the ata host which implements a queue depth less than 32 Date: Wed, 30 Jul 2014 14:15:10 +0200 Message-Id: <7e8fe9628fa3b778bf8b00c5faead306e80c0a47.1406722270.git.jslaby@suse.cz> X-Mailer: git-send-email 2.0.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kevin Hao 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 1871ee134b73fb4cadab75752a7152ed2813c751 upstream. The sata on fsl mpc8315e is broken after the commit 8a4aeec8d2d6 ("libata/ahci: accommodate tag ordered controllers"). The reason is that the ata controller on this SoC only implement a queue depth of 16. When issuing the commands in tag order, all the commands in tag 16 ~ 31 are mapped to tag 0 unconditionally and then causes the sata malfunction. It makes no senses to use a 32 queue in software while the hardware has less queue depth. So consider the queue depth implemented by the hardware when requesting a command tag. Fixes: 8a4aeec8d2d6 ("libata/ahci: accommodate tag ordered controllers") Signed-off-by: Kevin Hao Acked-by: Dan Williams Signed-off-by: Tejun Heo Signed-off-by: Jiri Slaby --- drivers/ata/libata-core.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c index d2eb9df3da3d..97b5e01a6814 100644 --- a/drivers/ata/libata-core.c +++ b/drivers/ata/libata-core.c @@ -4787,6 +4787,10 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words) * ata_qc_new - Request an available ATA command, for queueing * @ap: target port * + * Some ATA host controllers may implement a queue depth which is less + * than ATA_MAX_QUEUE. So we shouldn't allocate a tag which is beyond + * the hardware limitation. + * * LOCKING: * None. */ @@ -4794,14 +4798,16 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words) static struct ata_queued_cmd *ata_qc_new(struct ata_port *ap) { struct ata_queued_cmd *qc = NULL; - unsigned int i, tag; + unsigned int i, tag, max_queue; + + max_queue = ap->scsi_host->can_queue; /* no command while frozen */ if (unlikely(ap->pflags & ATA_PFLAG_FROZEN)) return NULL; - for (i = 0; i < ATA_MAX_QUEUE; i++) { - tag = (i + ap->last_tag + 1) % ATA_MAX_QUEUE; + for (i = 0, tag = ap->last_tag + 1; i < max_queue; i++, tag++) { + tag = tag < max_queue ? tag : 0; /* the last tag is reserved for internal command. */ if (tag == ATA_TAG_INTERNAL) @@ -6184,6 +6190,16 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht) { int i, rc; + /* + * The max queue supported by hardware must not be greater than + * ATA_MAX_QUEUE. + */ + if (sht->can_queue > ATA_MAX_QUEUE) { + dev_err(host->dev, "BUG: the hardware max queue is too large\n"); + WARN_ON(1); + return -EINVAL; + } + /* host must have been started */ if (!(host->flags & ATA_HOST_STARTED)) { dev_err(host->dev, "BUG: trying to register unstarted host\n"); -- 2.0.1 -- 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/