From: Marc Kleine-Budde <mkl@pengutronix.de>
To: David Jander <david@protonic.nl>
Cc: wg@grandegger.com, linux-can@vger.kernel.org
Subject: Re: [PATCH 1/3] can: flexcan.c: Correctly initialize mailboxes
Date: Tue, 02 Sep 2014 12:59:42 +0200 [thread overview]
Message-ID: <5405A31E.1060403@pengutronix.de> (raw)
In-Reply-To: <20140902123725.01808f36@archvile>
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On 09/02/2014 12:37 PM, David Jander wrote:
> On Tue, 02 Sep 2014 12:24:28 +0200
> Marc Kleine-Budde <mkl@pengutronix.de> wrote:
>
>> On 08/27/2014 11:58 AM, David Jander wrote:
>>> Apparently mailboxes may contain random data at startup, causing some of
>>> them being prepared for message reception. This causes overruns being
>>> missed or even confusing the IRQ check for trasmitted messages, increasing
>>> the transmit counter instead of the error counter.
>>>
>>> Signed-off-by: David Jander <david@protonic.nl>
>>
>> Before patch
>>
>> 0d1862e can: flexcan: fix flexcan_chip_start() on imx6
>>
>> there was a loop clearing the whole cantxfg register space. But this
>> turned out to be bogus, as message buffers 1...7 are reserved by the
>> FIFO engine and we're not allowed to tough them. This lead to some kind
>> of abort on imx6.
>>
>> You may need this patch once you don't make use of the FIFO engine any more.
>
> You will need this patch in either case, but indeed, if you use the FIFO, you
> should skip the MB's that are shadowed by the FIFO.
ACK
> If you don't clear the rest of the MB's they may still contain random data and
> the problem remains.
> IMHO 0d1862e is wrong, since buffers are not in reset default values. There is
> no indication of that in the reference manual, and I have observed that they
> are indeed not cleared after reset.
Yes, 0d1862e was not complete, the initialisation was fixes with:
d5a7b40 can: flexcan: flexcan_chip_start: fix regression,
mark one MB for TX and abort pending TX
Which sets FLEXCAN_MCR_MAXMB to 8, which is the only mailbox used for tx
and the code of the tx mailbox is set to 0x4 == tx, inactive.
This should be enough in FIFO mode, correct?
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Industrial Linux Solutions | Phone: +49-231-2826-924 |
Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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next prev parent reply other threads:[~2014-09-02 10:59 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-27 9:58 [PATCH 0/3] Decrease likelyhood of RX overruns David Jander
2014-08-27 9:58 ` [PATCH 1/3] can: flexcan.c: Correctly initialize mailboxes David Jander
2014-09-02 10:24 ` Marc Kleine-Budde
2014-09-02 10:37 ` David Jander
2014-09-02 10:59 ` Marc Kleine-Budde [this message]
2014-09-02 11:15 ` David Jander
2014-09-02 13:54 ` Marc Kleine-Budde
2014-09-02 14:27 ` David Jander
2014-09-02 11:32 ` David Jander
2014-09-02 11:38 ` Marc Kleine-Budde
2014-09-02 14:53 ` Marc Kleine-Budde
2014-08-27 9:58 ` [PATCH 2/3] can: flexcan.c: Re-write receive path to use MB queue instead of FIFO David Jander
2014-09-02 11:30 ` Marc Kleine-Budde
2014-09-02 12:04 ` David Jander
2014-09-02 14:53 ` Marc Kleine-Budde
2014-09-03 7:19 ` David Jander
2014-09-03 9:12 ` Marc Kleine-Budde
2014-09-03 15:42 ` David Jander
2014-08-27 9:58 ` [PATCH 3/3] can: flexcan.c: Implement last step of workaround for errata ERR005829 David Jander
2014-09-02 11:28 ` Marc Kleine-Budde
2014-09-02 11:36 ` David Jander
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