libata: add deadline support to prereset and reset methods

Add @deadline to prereset and reset methods and make them honor it.
ata_wait_ready() which directly takes @deadline is implemented to be
used as the wait function.  This patch is in preparation for EH timing
improvements.

* ata_wait_ready() never does busy sleep.  It's only used from EH and
  no wait in EH is that urgent.  This function also prints 'be
  patient' message automatically after 5 secs of waiting if more than
  3 secs is remaining till deadline.

* ata_bus_post_reset() now fails with error code if any of its wait
  fails.  This is important because earlier reset tries will have
  shorter timeout than the spec requires.  If a device fails to
  respond before the short timeout, reset should be retried with
  longer timeout rather than silently ignoring the device.

  There are three behavior differences.

  1. Timeout is applied to both devices at once, not separately.  This
     is more consistent with what the spec says.

  2. When a device passes devchk but fails to become ready before
     deadline.  Previouly, post_reset would just succeed and let
     device classification remove the device.  New code fails the
     reset thus causing reset retry.  After a few times, EH will give
     up disabling the port.

  3. When slave device passes devchk but fails to become accessible
     (TF-wise) after reset.  Original code disables dev1 after 30s
     timeout and continues as if the device doesn't exist, while the
     patched code fails reset.  When this happens, new code fails
     reset on whole port rather than proceeding with only the primary
     device.

  If the failing device is suffering transient problems, new code
  retries reset which is a better behavior.  If the failing device is
  actually broken, the net effect is identical to it, but not to the
  other device sharing the channel.  In the previous code, reset would
  have succeeded after 30s thus detecting the working one.  In the new
  code, reset fails and whole port gets disabled.  IMO, it's a
  pathological case anyway (broken device sharing bus with working
  one) and doesn't really matter.

* ata_bus_softreset() is changed to return error code from
  ata_bus_post_reset().  It used to return 0 unconditionally.

* Spin up waiting is to be removed and not converted to honor
  deadline.

* To be on the safe side, deadline is set to 40s for the time being.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/ata/pata_sil680.c b/drivers/ata/pata_sil680.c
index 6770820cfca..a5886f061c0 100644
--- a/drivers/ata/pata_sil680.c
+++ b/drivers/ata/pata_sil680.c
@@ -94,11 +94,13 @@ static int sil680_cable_detect(struct ata_port *ap) {
 /**
  *	sil680_bus_reset	-	reset the SIL680 bus
  *	@ap: ATA port to reset
+ *	@deadline: deadline jiffies for the operation
  *
  *	Perform the SIL680 housekeeping when doing an ATA bus reset
  */
 
-static int sil680_bus_reset(struct ata_port *ap,unsigned int *classes)
+static int sil680_bus_reset(struct ata_port *ap,unsigned int *classes,
+			    unsigned long deadline)
 {
 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
 	unsigned long addr = sil680_selreg(ap, 0);
@@ -108,7 +110,7 @@ static int sil680_bus_reset(struct ata_port *ap,unsigned int *classes)
 	pci_write_config_byte(pdev, addr, reset | 0x03);
 	udelay(25);
 	pci_write_config_byte(pdev, addr, reset);
-	return ata_std_softreset(ap, classes);
+	return ata_std_softreset(ap, classes, deadline);
 }
 
 static void sil680_error_handler(struct ata_port *ap)