From: Wolfgang Grandegger <wg-5Yr1BZd7O62+XT7JhA+gdA@public•gmane.org>
To: Marc Kleine-Budde <mkl-bIcnvbaLZ9MEGnE8C9+IrQ@public•gmane.org>
Cc: socketcan-core-0fE9KPoRgkgATYTw5x5z8w@public•gmane.org,
netdev-u79uwXL29TY76Z2rM5mHXA@public•gmane.org
Subject: Re: [PATCH] socketcan: add a driver for FlexCAN controllers.
Date: Fri, 18 Jun 2010 14:30:41 +0200 [thread overview]
Message-ID: <4C1B66F1.1060605@grandegger.com> (raw)
In-Reply-To: <4C1B5E1F.5080702-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>
On 06/18/2010 01:53 PM, Wolfgang Grandegger wrote:
> On 06/18/2010 01:21 PM, Marc Kleine-Budde wrote:
>> Wolfgang Grandegger wrote:
>>> On 06/18/2010 12:44 PM, Marc Kleine-Budde wrote:
>>>> Wolfgang Grandegger wrote:
>>>>> On 06/18/2010 12:16 PM, Marc Kleine-Budde wrote:
>>>>>> Wolfgang Grandegger wrote:
>>>>>>> Hi Hans-Jürgen,
>>>>>>>
>>>>>>> On 06/17/2010 12:52 PM, Hans J. Koch wrote:
>>>>>>>> This adds a driver for FlexCAN based CAN controllers,
>>>>>>>> e.g. found in Freescale i.MX35 SoCs.
>>>>>>>>
>>>>>>>> The original version of this driver was posted by Sascha Hauer in July 2009:
>>>>>>>> http://kerneltrap.org/mailarchive/linux-netdev/2009/7/29/6251621
>>>>>>>>
>>>>>>>> I took this version, added NAPI support, and fixed some problems found
>>>>>>>> during testing. Well, here is the result. Please review.
>>>>>>> I briefly browsed the patch and various bits and pieces are missing or
>>>>>>> not correctly implemented. Marc already pointed out a few of them:
>>>>>>>
>>>>>>> - I do not find can_put/get_echo_skb functions in the code. How is
>>>>>>> IFF_ECHO supposed to work?
>>>>>> the driver uses hardware loopback
>>>>> OK, then
>>>>>
>>>>> dev = alloc_candev(sizeof(struct flexcan_priv), 0);
>>>>>
>>>>> should be used (and TX_ECHO_SKB_MAX removed) in Hans-Jürgens driver.
>>>>>
>>>>>>> - Support for CAN_CTRLMODE_BERR_REPORTING and do_get_berr_counter()
>>>>>>> seems to be missing.
>>>>>>>
>>>>>>> - Make use of alloc_can_skb() and alloc_can_err_skb().
>>>>>> the last two points are already addressed in my version of the driver.
>>>>> I do not see support for CAN_CTRLMODE_BERR_REPORTING in your driver
>>>>> (which has nothing to do with do_get_berr_counter).
>>>> oh yes...sorry, got confused.
>>>>
>>>> However I implemented CAN_CTRLMODE_BERR_REPORTING, i.e. turning of the
>>>> bit error interrupts by default. This has the effect that no bus warning
>>>> and bus passive interrupt was signalled.
>>>>
>>>> I should add a comment to my driver.
>>>
>>> I'm confused, CAN_CTRLMODE_BERR_REPORTING means that the user can enable
>>> bus error reporting, which seems not be handled in the driver your sent.
>>> See:
>>>
>>> http://lxr.linux.no/linux/drivers/net/can/sja1000/sja1000.c#L134
>>> http://lxr.linux.no/linux/drivers/net/can/sja1000/sja1000.c#L588
>>
>> Which interrupts does "IRQ_BEI" include? What should
>> CAN_CTRLMODE_BERR_REPORTING do?
>>
>> Looking at:
>> http://lxr.linux.no/linux+v2.6.34/drivers/net/can/sja1000/sja1000.c#L393
>> it seems that BEI on the SJA just effects bit, form and stuff errors.
>
> Yes, it effects *bus errors*... actually the one you handle in
> at91_poll_err_frame(). Especially the AT91_IRQ_AERR does cause the
> infamous interrupt flooding (which is, btw, not treated correctly as
> bus error in your driver).
>
>> If I disable the corresponding interrupt in the flexcan. This is
>> ERR_MSK, (1 << 14 in CTRL), I don't get error warning or error passive
>> interrupts either. I'm not sure about the bus off interrupt.
>
> Hm, my understanding is that you can disable those bus error
> interrupts individually via AT91_IRQ_ERR_FRAME.
>
>> From my point of view this is not that what CAN_CTRLMODE_BERR_REPORTING
>> should do, is it?
>
> It should *not* disable state change interrupts, of course. I have
> started to fix some issues in the at91 driver some time ago, which
> I have attached below.
Sorry, I drifted away to the at91 driver. If the flexcan hardware does
not allow to disable bus error reporting individually, just do *not*
support CAN_CTRLMODE_BERR_REPORTING, as you already do in your patch.
Wolfgang.
next prev parent reply other threads:[~2010-06-18 12:30 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-17 10:52 [PATCH] socketcan: add a driver for FlexCAN controllers Hans J. Koch
[not found] ` <20100617105201.GA2015-hikPBsva6T+Nj9Bq2fkWzw@public.gmane.org>
2010-06-17 14:10 ` Marc Kleine-Budde
2010-06-18 10:04 ` Wolfgang Grandegger
2010-06-18 9:47 ` Wolfgang Grandegger
[not found] ` <4C1B4098.3090800-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>
2010-06-18 10:16 ` Marc Kleine-Budde
[not found] ` <4C1B4796.3060506-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2010-06-18 10:33 ` Wolfgang Grandegger
[not found] ` <4C1B4B85.3010905-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>
2010-06-18 10:44 ` Marc Kleine-Budde
[not found] ` <4C1B4DF0.2090103-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2010-06-18 11:04 ` Wolfgang Grandegger
[not found] ` <4C1B52A7.3060607-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>
2010-06-18 11:21 ` Marc Kleine-Budde
[not found] ` <4C1B56BC.1050303-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2010-06-18 11:53 ` Wolfgang Grandegger
[not found] ` <4C1B5E1F.5080702-5Yr1BZd7O62+XT7JhA+gdA@public.gmane.org>
2010-06-18 12:30 ` Wolfgang Grandegger [this message]
2010-06-18 12:00 ` Hans J. Koch
[not found] ` <20100618120044.GB2007-hikPBsva6T+Nj9Bq2fkWzw@public.gmane.org>
2010-06-18 12:19 ` Wolfgang Grandegger
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4C1B66F1.1060605@grandegger.com \
--to=wg-5yr1bzd7o62+xt7jha+gda@public$(echo .)gmane.org \
--cc=mkl-bIcnvbaLZ9MEGnE8C9+IrQ@public$(echo .)gmane.org \
--cc=netdev-u79uwXL29TY76Z2rM5mHXA@public$(echo .)gmane.org \
--cc=socketcan-core-0fE9KPoRgkgATYTw5x5z8w@public$(echo .)gmane.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox