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

From: Suganath Prabu Subramani
Date: Thu Jun 20 2019 - 03:09:29 EST


Acked-by: Suganath Prabu <suganath-prabu.subramani@xxxxxxxxxxxx>

On Thu, Jun 20, 2019 at 12:34 PM Suganath Prabu Subramani
<suganath-prabu.subramani@xxxxxxxxxxxx> wrote:
>
> Please consider this as Acked-by: Suganath Prabu
> <suganath-prabu.subramani@xxxxxxxxxxxx>
>
>
> On Tue, Jun 18, 2019 at 6:16 AM Ming Lei <tom.leiming@xxxxxxxxx> wrote:
> >
> > On Mon, Jun 17, 2019 at 8:21 PM Christoph Hellwig <hch@xxxxxx> 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@xxxxxx>
> > > ---
> > > 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