Re: [PATCH 11/12] libata: use IRQ expecting

From: Jeff Garzik
Date: Thu Jun 24 2010 - 20:22:49 EST

On 06/13/2010 11:31 AM, Tejun Heo wrote:
Thanks to its age, ATA is very susceptible to IRQ delivery problems in
both directions - lost and spurious interrupts. In traditional PATA,
the IRQ line is ultimately out of the controller and driver's control.
Even relatively new SATA isn't free from these issues. Many
controllers still emulate the traditional IDE interface which doesn't
have reliable way to indicate interrupt pending state and there also
is an issue regarding the interpretation of nIEN on both sides of the

Most of these problems can be worked around by using the new IRQ
expecting mechanism without adding noticeable overhead. In ATA,
almost all operations are initiated by the host and the controller
signals progress or completion using IRQ. IRQ expecting can easily be
added in libata core and applied to all libata drivers.

Signed-off-by: Tejun Heo<tj@xxxxxxxxxx>
drivers/ata/libata-core.c | 15 +++++++++++++--
drivers/ata/libata-eh.c | 4 +++-
drivers/ata/libata-sff.c | 37 +++++++++++++++++++------------------
include/linux/libata.h | 2 ++
4 files changed, 37 insertions(+), 21 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index ddf8e48..9a0aaa0 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4972,6 +4972,8 @@ void ata_qc_complete(struct ata_queued_cmd *qc)
struct ata_port *ap = qc->ap;

+ unexpect_irq(ap->irq_expect, false);
/* XXX: New EH and old EH use different mechanisms to
* synchronize EH with regular execution path.

Unconditional use of unexpect_irq() here seems incorrect for some cases, such as sata_mv's use, where ata_qc_complete() is called multiple times rather than a singleton ata_qc_complete_multiple() call.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at