The following commit was intended to fix problems with specific AHCI
controller(s) that would become bricks if the AHCI specification was not
followed strictly (that is, if ahci_start_engine() was called while the
controller was in the wrong state):
commit 7faa33da9b7add01db9f1ad92c6a5d9145e940a7
ahci: start engine only during soft/hard resets
However, some devices currently have issues with that fix, so we must
implement a flag that delays the ahci_start_engine() call only for specific
controllers.
This commit simply introduces the flag, without enabling it in any driver.
Note that even when AHCI_HFLAG_DELAY_ENGINE is not enabled, this patch does
not constitue a full revert to commit 7faa33da; there is still a change in
behavior to the ahci_port_suspend() failure path.
Signed-off-by: Brian Norris <computersforpeace@xxxxxxxxx>
---
drivers/ata/ahci.h | 3 +++
drivers/ata/libahci.c | 5 +++++
2 files changed, 8 insertions(+), 0 deletions(-)
diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index b175000..feb127e 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -210,6 +210,9 @@ enum {
AHCI_HFLAG_NO_SNTF = (1 << 12), /* no sntf */
AHCI_HFLAG_NO_FPDMA_AA = (1 << 13), /* no FPDMA AA */
AHCI_HFLAG_YES_FBS = (1 << 14), /* force FBS cap on */
+ AHCI_HFLAG_DELAY_ENGINE = (1 << 15), /* do not start engine on
+ port start (wait until
+ error-handling stage) */
/* ap->flags bits */
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index a72bfd0..f9eaa82 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -737,6 +737,7 @@ static void ahci_power_down(struct ata_port *ap)
static void ahci_start_port(struct ata_port *ap)
{
+ struct ahci_host_priv *hpriv = ap->host->private_data;
struct ahci_port_priv *pp = ap->private_data;
struct ata_link *link;
struct ahci_em_priv *emp;
@@ -746,6 +747,10 @@ static void ahci_start_port(struct ata_port *ap)
/* enable FIS reception */
ahci_start_fis_rx(ap);
+ /* enable DMA */
+ if (!(hpriv->flags & AHCI_HFLAG_DELAY_ENGINE))
+ ahci_start_engine(ap);
+
/* turn on LEDs */
if (ap->flags & ATA_FLAG_EM) {
ata_for_each_link(link, ap, EDGE) {
--
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