Re: [PATCH 9/9] tcm_qla2xxx: Add special case for COMPARE_AND_WRITE data_direction

[Roland Dreier]

On Tue, Aug 20, 2013 at 1:08 PM, Nicholas A. Bellinger
<nab@xxxxxxxxxxxxx> wrote:
> Add a special case for COMPARE_AND_WRITE for the reverse data direction
> mapping used for pci_map_sg() + friends.

I don't understand this.  In fact the whole patch series looks quite
confused.  COMPARE AND WRITE is a normal Data-Out command, with no
requirement for special bidirectional handling or anything like that.
The only slightly unusual thing is that a CAW command with a NUMBER OF
LOGICAL BLOCKS equal to N will actually transfer 2*N worth of data --
one set of data for the compare operation and a second set to write if
the compare succeeds.  But just to be clear, the transfer of those 2*N
blocks happens as a single transfer during the Data-Out phase.

 - R.
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