linux-kernel - Re: canfdtest on flexcan loopback

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Message-ID: <12688d2b-a198-ef5e-dd8f-64957df36574@pengutronix.de>
Date:   Wed, 16 Sep 2020 13:32:49 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Vladimir Oltean <olteanv@...il.com>, wg@...ndegger.com,
        pankaj.bansal@....com, pankaj.bansal@....nxp.com,
        linux-can@...r.kernel.org
Cc:     qiangqing.zhang@....com, linux-kernel@...r.kernel.org,
        vladimir.oltean@....com
Subject: Re: canfdtest on flexcan loopback

On 9/16/20 1:04 PM, Vladimir Oltean wrote:
> [ resending, forgot to copy Wolfgang ]
> 
> On Wed 9/2/2020 10:09 AM, Wolfgang Grandegger wrote:
>> canfdtest normally runs on the DUT *and* a the host. The DUT receives
>> the messages from the host, increments the frame data bytes and then
>> sends them back to the host. With "loopback" mode, the data bytes are
>> not incremented and that's what you see above.
>>
>> Wolfgang
> 
> Wolfgang is of course right, but we're nonetheless investigating what
> seems to be a real problem, and what Pankaj had seen was a red herring.
> 
> So currently what I suspect is going on, when I am running canfdtest
> between 2 LS1028A-RDB boards, is that the DUT is reordering frames on
> TX.
> 
> See, for example, the screenshot below:
> https://drive.google.com/file/d/1rOeW3aXh3kPh1CJ39lCccRfjFz5JN5I6/view?usp=sharing
> 
> I have added trace points to the end of the flexcan_start_xmit function,
> which print the entire skb, and the frames appear to be written to the
> TX message buffer in the correct order. They are seen, however, in the
> incorrect order on the wire.

Which driver are you using? The mainline driver only uses one TX buffer.

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
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