kernel - Adjust AHCI driver to deal with AMD braindamage / 880G chipset

kernel - Adjust AHCI driver to deal with AMD braindamage / 880G chipset

* As of this writing AMD has some new chipsets out for AM3 MBs which
  supports AHCI on 5 SATA + 1 E-SATA connector.  My testing was done
  on a MB with the 880G chipset.

  The AHCI firmware for this chipset is a bit on the rough side.  It
  seems a bit slow on the INIT/device-detection sequencing (possibly due
  to longer PHY training time?  It's supposed to be a 6GBit PHY), and it
  generates a stream of PCS interrupts for some devices.

  My assumption is that the PCS interrupts are not being masked by the
  chipset during the INIT phase.  Both IFS and PCS interrupts seem to
  occur during INIT/RESET and PM probing stages.

  In addition, at least one drive... an Intel SSD, caused a large number
  of PCS interrupts during the INIT phase even when connected to an
  internal SATA port at power-on.  This is clearly a bug in the AMD
  AHCI chipset, again related to their firmware not internally masking
  communications glitches during INIT, and/or taking an extra long time
  to train the PHY.

* Adjust the AHCI driver to deal with this situation.  Limit the interrupt
  rate for PCS errors and do harsh reinitialization of the port when we get
  a PCS error, along with allowing extra time for the device detect to
  succeed.

* As a side benefit the AHCI driver should be able to deal with device
  connection and disconnection on non-hot-swap-capable ports, at least
  up to a point.

* Silence some of the console output during probe.

* Try harder to clear the CI/SACT registers when stopping a port.  Some
  chipsets appear to not clear the registers when we cycle ST when they
  have already stopped the command processor, possibly as part of the IFS
  or PCS interrupt paths.

* Fix a bug where an IFS or PCS interrupt marks a probe command (software
  reset sequence) as complete when it actually errored-out.

* Sleep longer between retries if a command fails due to an IFS error.
  When testing with the WD Green drives a drive inserted into a PM
  enclosure cold seems to take longer to start up during the COMRESET
  sequence.  This only seems to occur with the AMD chipset and does
  not occur with the older NVidia chipset.  IFS errors occur for several
  seconds beyond what I would consider a reasonable sleep interval.