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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Sinan Kaya <okaya@codeaurora.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	linux-pci@vger.kernel.org, sulrich@codeaurora.org,
	timur@codeaurora.org, linux-arm-msm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Mike Marciniszyn <mike.marciniszyn@intel.com>,
	Dennis Dalessandro <dennis.dalessandro@intel.com>,
	Doug Ledford <dledford@redhat.com>,
	"open list:HFI1 DRIVER" <linux-rdma@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>,
	Alex Deucher <alexander.deucher@amd.com>
Subject: Re: [PATCH 1/2] IB/hfi1: Try slot reset before secondary bus reset
Date: Fri, 20 Apr 2018 08:54:00 -0600	[thread overview]
Message-ID: <20180420145400.GA30433@ziepe.ca> (raw)
In-Reply-To: <20180419214722.GO28657@bhelgaas-glaptop.roam.corp.google.com>

On Thu, Apr 19, 2018 at 04:47:23PM -0500, Bjorn Helgaas wrote:
 
> I *thought* the hardware was supposed to automatically negotiate to
> the highest rate supported by both sides without any help at all from
> software.  But since several drivers have code to do it themselves, I
> wonder if I'm missing something, or maybe there's something the PCI
> core should be doing that it isn't, and the driver code is basically
> working around that PCI core deficiency.

The HW is supposed to do that, but Gen3 is electrically *hard*.

I'm not surprised that some HW has run into trouble where the driver
might have to be involved to tweak the SERDES.. eg there is now often
on-device software involved here and updating the SERDES 'firmware'
may be needed.

Jason

  parent reply	other threads:[~2018-04-20 14:54 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-19 19:56 Sinan Kaya
2018-04-19 19:56 ` [PATCH 2/2] PCI/AER: " Sinan Kaya
2018-04-27 18:51   ` Sinan Kaya
2018-04-19 20:26 ` [PATCH 1/2] IB/hfi1: " Jason Gunthorpe
2018-04-19 20:35   ` Sinan Kaya
2018-04-19 21:47   ` Bjorn Helgaas
2018-04-19 22:11     ` Deucher, Alexander
2018-04-20 14:12       ` Dennis Dalessandro
2018-04-20 14:55       ` Jason Gunthorpe
2018-04-19 22:19     ` Sinan Kaya
2018-04-20 14:00       ` Bjorn Helgaas
2018-04-20 14:23         ` Sinan Kaya
2018-04-20 15:04         ` Alex Williamson
2018-04-23 17:28           ` Sinan Kaya
2018-04-23 19:10             ` Alex Williamson
2018-04-23 20:17               ` Sinan Kaya
2018-04-23 20:23               ` Bjorn Helgaas
2018-04-23 20:41                 ` Alex Williamson
2018-04-25 14:13               ` Sinan Kaya
2018-04-20 14:54     ` Jason Gunthorpe [this message]
2018-06-19 21:43 ` Bjorn Helgaas
2018-06-19 22:21   ` Sinan Kaya
2018-06-22 14:01     ` Bjorn Helgaas
2018-06-22 16:04       ` Sinan Kaya

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