1. 25 Jan, 2016 1 commit
    • Danesh Petigara's avatar
      drivers: ata: wake port before DMA stop for ALPM · fb329633
      Danesh Petigara authored
      The AHCI driver code stops and starts port DMA engines at will
      without considering the power state of the particular port. The
      AHCI specification isn't very clear on how to handle this scenario,
      leaving implementation open to interpretation.
      
      Broadcom's STB SATA host controller is unable to handle port DMA
      controller restarts when the port in question is in low power mode.
      When a port enters partial or slumber mode, its PHY is powered down.
      When a controller restart is requested, the controller's internal
      state machine expects the PHY to be brought back up by software which
      never happens in this case, resulting in failures.
      
      To avoid this situation, logic is added to manually wake up the port
      just before its DMA engine is stopped, if the port happens to be in
      a low power state. HBA initiated power management ensures that the port
      eventually returns to its configured low power state, when the link is
      idle (as per the conditions listed in the spec). A new host flag is also
      added to ensure this logic is only exercised for hosts with the above
      limitation.
      
      tj: Formatting changes.
      Signed-off-by: default avatarDanesh Petigara <dpetigara@broadcom.com>
      Reviewed-by: default avatarMarkus Mayer <mmayer@broadcom.com>
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      fb329633
  2. 24 Jan, 2016 39 commits