From: "Allen Hubbe" <Allen.Hubbe@dell.com>
To: "'Logan Gunthorpe'" <logang@deltatee.com>,
<linux-ntb@googlegroups.com>, <linux-pci@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Cc: "'Jon Mason'" <jdmason@kudzu.us>,
"'Dave Jiang'" <dave.jiang@intel.com>,
"'Bjorn Helgaas'" <bhelgaas@google.com>,
"'Greg Kroah-Hartman'" <gregkh@linuxfoundation.org>,
"'Kurt Schwemmer'" <kurt.schwemmer@microsemi.com>,
"'Stephen Bates'" <sbates@raithlin.com>,
"'Serge Semin'" <fancer.lancer@gmail.com>
Subject: RE: [PATCH 06/16] ntb: add check and comment for link up to mw_count and mw_get_align
Date: Thu, 29 Jun 2017 17:35:50 -0400 [thread overview]
Message-ID: <000501d2f11f$af340d70$0d9c2850$@dell.com> (raw)
In-Reply-To:
Let me try that again...
From: Hubbe, Allen
> From: Logan Gunthorpe
> > On 6/29/2017 2:13 PM, Allen Hubbe wrote:
> > > Unfortunately, it is to work around hardware errata. That is not so trivial to fix.
> >
> > Can you describe more what the work around is doing? Can you share the
> > code? It seems odd that a workaround is based on the alignment
> > restrictions of the mws.
>
> Sure, while not making any claim that this is ready for upstream.
>
> It is not a workaround for alignment restrictions of the mws. It is a restriction to avoid the use of
> doorbells and scratchpads. Memory windows are used exclusively.
>
> Read msi-x local <addr,data> and send that to the peer:
https://github.com/ntrdma/ntrdma/blob/master/drivers/ntc/ntc_ntb_msi.c#L583
> Transform peer's addr to the memory window region:
https://github.com/ntrdma/ntrdma/blob/master/drivers/ntc/ntc_ntb_msi.c#L603
> Append a dma immediate value operation after other operations, to write the data at addr:
https://github.com/ntrdma/ntrdma/blob/master/drivers/ntc/ntc_ntb_msi.c#L1195
>
> Above describes the workaround.
>
> Used in the context of a rdma-over-ntb driver here:
> https://github.com/ntrdma/ntrdma/blob/master/drivers/infiniband/hw/ntrdma/ntrdma_qp.c#L1585
>
> >
> > Logan
next prev parent reply other threads:[~2017-06-29 21:36 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-29 3:26 [PATCH 00/16] Logan Gunthorpe
2017-06-29 3:26 ` [PATCH 01/16] switchtec: move structure definitions into a common header Logan Gunthorpe
2017-07-05 19:37 ` Bjorn Helgaas
2017-06-29 3:26 ` [PATCH 02/16] switchtec: export class symbol for use in upper layer driver Logan Gunthorpe
2017-06-29 3:26 ` [PATCH 03/16] switchtec: add ntb hardware register definitions Logan Gunthorpe
2017-06-29 3:26 ` [PATCH 04/16] switchtec: add link event notifier callback Logan Gunthorpe
2017-06-29 3:26 ` [PATCH 05/16] ntb: ensure ntb_mw_get_align is only called when the link is up Logan Gunthorpe
2017-06-29 18:11 ` Allen Hubbe
2017-06-29 3:26 ` [PATCH 06/16] ntb: add check and comment for link up to mw_count and mw_get_align Logan Gunthorpe
2017-06-29 18:11 ` Allen Hubbe
2017-06-29 19:00 ` Logan Gunthorpe
2017-06-29 20:13 ` Allen Hubbe
2017-06-29 20:17 ` Logan Gunthorpe
2017-06-29 21:27 ` Hubbe, Allen
2017-06-29 21:35 ` Allen Hubbe [this message]
2017-06-29 22:14 ` Logan Gunthorpe
2017-06-29 3:26 ` [PATCH 07/16] ntb: ntb_test: ensure the link is up before trying to configure the mws Logan Gunthorpe
2017-06-29 3:26 ` [PATCH 08/16] switchtec_ntb: introduce initial ntb driver Logan Gunthorpe
2017-06-29 3:26 ` [PATCH 09/16] switchtec_ntb: initialize hardware for memory windows Logan Gunthorpe
2017-06-29 3:26 ` [PATCH 10/16] switchtec_ntb: initialize hardware for doorbells and messages Logan Gunthorpe
2017-06-29 3:26 ` [PATCH 11/16] switchtec_ntb: add skeleton ntb driver Logan Gunthorpe
2017-06-29 3:26 ` [PATCH 12/16] switchtec_ntb: add link management Logan Gunthorpe
2017-06-29 18:11 ` Allen Hubbe
2017-06-29 18:37 ` Logan Gunthorpe
2017-06-29 3:26 ` [PATCH 13/16] switchtec_ntb: implement doorbell registers Logan Gunthorpe
2017-07-05 19:42 ` Bjorn Helgaas
2017-06-29 3:26 ` [PATCH 14/16] switchtec_ntb: implement scratchpad registers Logan Gunthorpe
2017-06-29 18:11 ` Allen Hubbe
2017-06-29 18:33 ` Logan Gunthorpe
2017-06-29 3:26 ` [PATCH 15/16] switchtec_ntb: add memory window support Logan Gunthorpe
2017-07-05 19:46 ` Bjorn Helgaas
2017-06-29 3:26 ` [PATCH 16/16] switchtec_ntb: update switchtec documentation with notes for ntb Logan Gunthorpe
2017-06-29 15:15 ` [PATCH 00/16] Greg Kroah-Hartman
2017-06-29 15:37 ` Logan Gunthorpe
2017-07-05 19:47 ` Bjorn Helgaas
2017-07-05 19:50 ` Logan Gunthorpe
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