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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

WARNING: multiple messages have this Message-ID (diff)
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


  parent reply	other threads:[~2017-06-29 21:36 UTC|newest]

Thread overview: 47+ 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 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 18:11     ` Allen Hubbe
2017-06-29 18:11     ` Allen Hubbe
2017-06-29 19:00     ` Logan Gunthorpe
2017-06-29 20:13       ` Allen Hubbe
2017-06-29 20:13         ` Allen Hubbe
2017-06-29 20:13         ` Allen Hubbe
2017-06-29 20:17         ` Logan Gunthorpe
2017-06-29 21:27           ` Hubbe, Allen
2017-06-29 21:27             ` Hubbe, Allen
2017-06-29 21:35           ` Allen Hubbe [this message]
2017-06-29 21:35             ` Allen Hubbe
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 18:11     ` Allen Hubbe
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 18:11     ` Allen Hubbe
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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