linux-kernel - Re: [PATCH net-next-2.6 v2] can: Topcliff: PCH

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Message-ID: <4CE63C05.6060101@grandegger.com>
Date:	Fri, 19 Nov 2010 09:57:41 +0100
From:	Wolfgang Grandegger <wg@...ndegger.com>
To:	Tomoya MORINAGA <tomoya-linux@....okisemi.com>
CC:	"David S. Miller" <davem@...emloft.net>,
	Wolfram Sang <w.sang@...gutronix.de>,
	Christian Pellegrin <chripell@...e.org>,
	Barry Song <21cnbao@...il.com>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	socketcan-core@...ts.berlios.de, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, andrew.chih.howe.khor@...el.com,
	qi.wang@...el.com, margie.foster@...el.com, yong.y.wang@...el.com,
	Masayuki Ohtake <masa-korg@....okisemi.com>,
	kok.howg.ewe@...el.com, joel.clark@...el.com
Subject: Re: [PATCH net-next-2.6 v2] can: Topcliff: PCH_CAN driver: Add Flow
 control,

Hi Tomoya,

On 11/19/2010 08:36 AM, Tomoya MORINAGA wrote:
> On Tuesday, November 16, 2010 7:16 PM, Wolfgang Grandegger wrote :
> 
>>> ......It seems the same line continues forever.
>>
>> Yes, it will continue until you connect the cable, that's normal
>> behavior. But that's not the full sequence. Could you please repeat the
>> test as shown below:
>>
>>   First start the following command in a *separate* session.
>>   # candump any,0:0,#FFFFFFFF"
>>
>>   Then setup and start the CAN controller:
>>   # ip link set can0 up type can bitrate 125000
>>   # cansend can0 123#deadbeef
>>
> 
> I show the result of the above command below,
> 
> [root@...alhost can-utils]# candump any,0:0,#FFFFFFFF
>   can0  20000020  [8] 00 00 00 00 00 00 08 00   ERRORFRAME
>   can0  20000020  [8] 00 00 00 00 00 00 10 00   ERRORFRAME
>   can0  20000020  [8] 00 00 00 00 00 00 18 00   ERRORFRAME
>   can0  20000020  [8] 00 00 00 00 00 00 20 00   ERRORFRAME
>   can0  20000020  [8] 00 00 00 00 00 00 28 00   ERRORFRAME
>   can0  20000020  [8] 00 00 00 00 00 00 30 00   ERRORFRAME
>   can0  20000020  [8] 00 00 00 00 00 00 38 00   ERRORFRAME
>   can0  20000020  [8] 00 00 00 00 00 00 40 00   ERRORFRAME
>   can0  20000020  [8] 00 00 00 00 00 00 48 00   ERRORFRAME
>   can0  20000020  [8] 00 00 00 00 00 00 50 00   ERRORFRAME
>   can0  20000020  [8] 00 00 00 00 00 00 58 00   ERRORFRAME

The above lines describe bus errors. Therefore it should be

    can0  20000088  [8] 00 00 80 19 00 00 58 00   ERRORFRAME

>   can0  20000024  [8] 00 00 00 00 00 00 60 00   ERRORFRAME

The TX error counter has reached 96 signaling a can error state change
to "error warning".

>   can0  20000024  [8] 00 08 00 00 00 00 68 00   ERRORFRAME

CAN_ERR_CRTL in the id and CAN_ERR_CRTL_TX_WARNING in data[1], but ...

>   can0  20000024  [8] 00 08 00 00 00 00 70 00   ERRORFRAME

the state change should be signaled only *once*.

>   can0  20000024  [8] 00 08 00 00 00 00 78 00   ERRORFRAME
>   can0  20000024  [8] 00 28 00 00 00 00 80 00   ERRORFRAME

"Error passive" state is reached and CAN_ERR_CRTL_TX_PASSIVE sould be
set in data[1], but CAN_ERR_CRTL_TX_WARNING should be removed.

>   can0  20000024  [8] 00 28 00 00 00 00 80 00   ERRORFRAME
>   can0  20000024  [8] 00 28 00 00 00 00 80 00   ERRORFRAME
>   can0  20000024  [8] 00 28 00 00 00 00 80 00   ERRORFRAME

Sounds magic, well, I'm going to prepare a patch as soon as your pending
patch series is applied.

Could you please do the same testing while triggering a bus-off? After
the test, the output of "ip -d -s link" would be interesting as well.

Thanks,

Wolfgang.
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