[PATCH 03/17] cxlflash: Reset hardware queue context via specified register

[Matthew R. Ochs]

> On Jun 21, 2017, at 9:14 PM, Uma Krishnan <ukrishn at linux.vnet.ibm.com> wrote:
> 
> Per the SISLite specification, context_reset() writes 0x1 to the LSB of the
> reset register. When the AFU processes this reset request, it is expected
> to clear the bit after reset is complete. The current implementation simply
> checks that the entire value read back is not 1, instead of masking off the
> LSB and evaluating it for a change to 0. Should the AFU manipulate other
> bits during the reset (reading back a value of 0xF for example), successful
> completion will be prematurely indicated given the existing logic.
> 
> Additionally, in the event that the context reset operation fails, there
> does not currently exist a way to provide feedback to the initiator of the
> reset. This poses a problem for the rare case that a context reset fails as
> the caller will proceed on the assumption that all is well.
> 
> To remedy these issues, refactor the context reset routine to only mask off
> the LSB when evaluating for success and return status to the caller. Also
> update the context reset handler parameters to pass a hardware queue
> reference instead of a single command to better reflect that the entire
> queue associated with the context is impacted by the reset.
> 
> Signed-off-by: Uma Krishnan <ukrishn at linux.vnet.ibm.com>

Acked-by: Matthew R. Ochs <mrochs at linux.vnet.ibm.com>