From 078890ca21d7e9414ea4b948bbe0e28cb1ab640c Mon Sep 17 00:00:00 2001 From: Kevin Hao Date: Sat, 12 Jul 2014 12:08:24 +0800 Subject: [PATCH] libata: support the ata host which implements a queue depth less than 32 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: Ben Hutchings --- 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 2b662725fd90..e8052f843235 100644 --- a/drivers/ata/libata-core.c +++ b/drivers/ata/libata-core.c @@ -4711,6 +4711,10 @@ 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. */ @@ -4718,14 +4722,16 @@ 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) @@ -5998,6 +6004,16 @@ 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"); -- 2.39.2