linux-kernel - Re: [PATCH v2 0/8] Fix breakage caused by the NTB multi-port patchset

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Message-ID: <20180917151622.lnlckvkiyqqxlt4c@alfbook-pro.local>
Date:   Mon, 17 Sep 2018 18:16:23 +0300
From:   Alexander Fomichev <fomichev.ru@...il.com>
To:     Logan Gunthorpe <logang@...tatee.com>
Cc:     linux-kernel@...r.kernel.org, linux-ntb@...glegroups.com,
        Jon Mason <jdmason@...zu.us>, Allen Hubbe <allenbh@...il.com>,
        Serge Semin <fancer.lancer@...il.com>,
        Shyam Sundar S K <Shyam-sundar.S-k@....com>,
        Shuah Khan <shuah@...nel.org>, Doug Meyer <dmeyer@...aio.com>,
        linux@...ro.com
Subject: Re: [PATCH v2 0/8] Fix breakage caused by the NTB multi-port patchset

On Fri, Jul 20, 2018 at 12:00:26PM -0600, Logan Gunthorpe wrote:

> To reiterate the main points on the feedback: the switchtec driver,
> in the cross link mode, will not be able to implement the port number
> function callbacks and will have to always return 0. It's a physical
> impossibility due to the symmetry. Therefore, in order fix this feature
> (which worked when merged), the clients must be changed to support not
> knowing the port number in the way they worked previously (ie. a legacy
> mode where there will only be two ports and you know there will be two
> sets of doorbells, one for each peer). The majority of this patch set
> fixes these issues.
> 
> The other point of controversy is the dma mask. I still strongly
> disagree with doing it in the driver as the code is clearly common
> to all and not at all driver specific. Moreover, I think as written,
> it is extra dangerous seeing all impleminting drivers are operating on
> the new struct device before it's initialized in ntb_register().
> Patch 2 in this series also fixes that.
> 
> [...]
> 
> Logan Gunthorpe (8):
>   NTB: ntb_tool: reading the link file should not end in a NULL byte
>   NTB: Setup the DMA mask globally for all drivers
>   NTB: Fix the default port and peer numbers for legacy drivers
>   NTB: ntb_pingpong: Choose doorbells based on port number
>   NTB: perf: Don't require one more memory window than number of peers
>   NTB: perf: Fix support for hardware that doesn't have port numbers
>   NTB: perf: Fix race condition when run with ntb_test
>   NTB: ntb_test: Fix bug when counting remote files

Tested successfully on i5-based desktop PC, NTB on PM8535 chip, both
ends are on the local system.

Tested-by: Alexander Fomichev <fomichev.ru@...il.com>

-- 
Regards,
  Alexander