1. 09 Jan, 2012 1 commit
    • Tejun Heo's avatar
      ahci: start engine only during soft/hard resets · 7faa33da
      Tejun Heo authored
      This is another attempt at fixing the same problem that 270dac35
      (libata: ahci_start_engine compliant to AHCI spec) tried to solve.
      Unfortunately, 270dac35 created regressions for a lot more common
      controllers and got reverted.
      
      This specific AHCI IP block becomes a brick if the DMA engine is
      started while DRQ is set.  It is not possible to avoid the condition
      completely but the most common occurrence is caused by spurious use of
      ahci_start_engine() from ahci_start_port() during init sequence.
      
      DMA engine is started after both soft and hard resets and
      ahci_start_port() is always followed by resets, so there is no reason
      to start DMA engine from ahci_start_port().
      
      This patch removes ahci_start_engine() invocation from
      ahci_start_port().  This change makes failure path of
      ahci_port_suspend() leave engine stopped without following resets.
      This is resolved by replacing ahci_start_port() call with
      ata_port_freeze() which forces resets afterwards, which is the better
      behavior anyway.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Reported-by: default avatarBrian Norris <computersforpeace@gmail.com>
      Reported-by: default avatarJian Peng <jipeng2005@gmail.com>
      Signed-off-by: default avatarJeff Garzik <jgarzik@redhat.com>
      7faa33da
  2. 04 Jan, 2012 13 commits
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