From: Jason Gunthorpe <jgg@ziepe.ca>
To: "Marciniszyn, Mike" <mike.marciniszyn@intel.com>
Cc: "Dalessandro, Dennis" <dennis.dalessandro@intel.com>,
"dledford@redhat.com" <dledford@redhat.com>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
"Wan, Kaike" <kaike.wan@intel.com>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
"Erwin, James" <james.erwin@intel.com>
Subject: Re: [PATCH for-rc 1/4] IB/hfi1: Allow for all speeds higher than gen3
Date: Wed, 30 Oct 2019 15:07:54 -0300 [thread overview]
Message-ID: <20191030180754.GA31799@ziepe.ca> (raw)
In-Reply-To: <32E1700B9017364D9B60AED9960492BC729594E1@fmsmsx120.amr.corp.intel.com>
On Tue, Oct 29, 2019 at 09:19:34PM +0000, Marciniszyn, Mike wrote:
> > Subject: Re: [PATCH for-rc 1/4] IB/hfi1: Allow for all speeds higher than gen3
> >
> > On Fri, Oct 25, 2019 at 03:58:24PM -0400, Dennis Dalessandro wrote:
> > > From: James Erwin <james.erwin@intel.com>
> > >
> > > The driver avoids the gen3 speed bump when the parent
> > > bus speed isn't identical to gen3, 8.0GT/s. This is not
> > > compatible with gen4 and newer speeds.
> > >
> > > Fix by relaxing the test to explicitly look for the lower
> > > capability speeds which inherently allows for all future speeds.
> >
> > This description does not seem like stable material to me.
> >
>
> Having a card unknowingly operate at half speed would seem pretty serious to me.
Since gen4 systems are really new this also sounds like a new feature
to me.. You need to be concerned that changing the pci setup doesn't
cause regressions on existing systems too.
> Perhaps the description should say:
>
> IB/hfi1: Insure full Gen3 speed in a Gen4 system
And maybe explain what the actual user visible impact is here. Sounds
like plugging a card into a gen4 system will not run at gen3 speeds?
Jason
next prev parent reply other threads:[~2019-10-30 18:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-25 19:58 [PATCH for-rc 0/4] Few more rc fixes Dennis Dalessandro
2019-10-25 19:58 ` [PATCH for-rc 1/4] IB/hfi1: Allow for all speeds higher than gen3 Dennis Dalessandro
2019-10-29 19:52 ` Jason Gunthorpe
2019-10-29 21:19 ` Marciniszyn, Mike
2019-10-30 18:07 ` Jason Gunthorpe [this message]
2019-10-30 20:14 ` Marciniszyn, Mike
2019-11-01 19:39 ` Marciniszyn, Mike
2019-10-25 19:58 ` [PATCH for-rc 2/4] IB/hfi1: Ensure r_tid_ack is valid before building TID RDMA ACK packet Dennis Dalessandro
2019-10-25 19:58 ` [PATCH for-rc 3/4] IB/hfi1: Calculate flow weight based on QP MTU for TID RDMA Dennis Dalessandro
2019-10-25 19:58 ` [PATCH for-rc 4/4] IB/hfi1: TID RDMA WRITE should not return IB_WC_RNR_RETRY_EXC_ERR Dennis Dalessandro
2019-11-06 17:26 ` [PATCH for-rc 0/4] Few more rc fixes Jason Gunthorpe
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