Re: [PATCH 7/8] mpt3sas: set an unlimited max_segment_size for SAS 3.0 HBAs

[Suganath Prabu Subramani <suganath-prabu.subramani@broadcom.com>]

Please consider this as Acked-by: Suganath Prabu
<suganath-prabu.subramani@broadcom.com>


On Tue, Jun 18, 2019 at 6:16 AM Ming Lei <tom.leiming@gmail.com> wrote:
>
> On Mon, Jun 17, 2019 at 8:21 PM Christoph Hellwig <hch@lst.de> wrote:
> >
> > When using a virt_boundary_mask, as done for NVMe devices attached to
> > mpt3sas controllers we require an unlimited max_segment_size, as the
> > virt boundary merging code assumes that.  But we also need to propagate
> > that to the DMA mapping layer to make dma-debug happy.  The SCSI layer
> > takes care of that when using the per-host virt_boundary setting, but
> > given that mpt3sas only wants to set the virt_boundary for actual
> > NVMe devices we can't rely on that.  The DMA layer maximum segment
> > is global to the HBA however, so we have to set it explicitly.  This
> > patch assumes that mpt3sas does not have a segment size limitation,
> > which seems true based on the SGL format, but will need to be verified.
> >
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > ---
> >  drivers/scsi/mpt3sas/mpt3sas_scsih.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> > index 1ccfbc7eebe0..c719b807f6d8 100644
> > --- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> > +++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> > @@ -10222,6 +10222,7 @@ static struct scsi_host_template mpt3sas_driver_template = {
> >         .this_id                        = -1,
> >         .sg_tablesize                   = MPT3SAS_SG_DEPTH,
> >         .max_sectors                    = 32767,
> > +       .max_segment_size               = 0xffffffff,
>
> .max_segment_size should be aligned, either setting it here correctly or
> forcing to make it aligned in scsi-core.
>
> Thanks,
> Ming Lei