Hello.
On 11-07-2014 10:10, Kevin Hao wrote:
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")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Kevin Hao <haokexin@xxxxxxxxx>
---
v3: Use ap->scsi_host->can_queue for the queue depth implemented by hardware.
Patch 2 in v2 is also dropped due to this change.
v2: Remove the changes for the ata tag helper functions
Hi Tejun,
I didn't get explicit objection for the codes at http://marc.info/?l=linux-ide&m=140478830920334&w=2
So I assume that you are OK wit it. The code in this patch is the same as that,
just add the commit log.
drivers/ata/libata-core.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 8f3043165048..4792fea79acf 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4728,14 +4728,17 @@ 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;
+ WARN_ON_ONCE(max_queue > ATA_MAX_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;
Assigning 'tag' back to 'tag' is quite stupid, don't you think? Why not:
if (tag >= max_queue)
tag = 0;
MBR, Sergei
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