linux-kernel - Re: [PATCH] can: flexcan: bump FLEXCAN_TIMEOUT

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Date:   Thu, 21 Mar 2019 16:30:37 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Thomas Winding <twi@...f.com>, Fabio Estevam <festevam@...il.com>,
        Per Christensen <pnc@...f.com>,
        Rasmus Villemoes <Rasmus.Villemoes@...vas.se>,
        "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] can: flexcan: bump FLEXCAN_TIMEOUT_US to 250

On 3/21/19 3:34 PM, Rasmus Villemoes wrote:
> On 20/03/2019 14.18, Marc Kleine-Budde wrote:
>> On 3/7/19 4:00 PM, Rasmus Villemoes wrote:
>>> While trying to add support for the Flexcan modules on the MPC8309,
>>> I'm hitting ETIMEDOUT in flexcan_chip_disable(). With this, probing
>>> succeeds. Checking the leftover value of timeout with a primitive
>>>
>>>   pr_err("%s: timeout==%d\n", __func__, timeout);
>>>
>>> after the loop in chip_disable() typically shows values around 12-14,
>>> i.e. suggesting that it takes about 110-130 us for the LPM_ACK bit to
>>> appear. So a timeout value of about twice that seems reasonable.
>>>
>>> Signed-off-by: Rasmus Villemoes <rasmus.villemoes@...vas.dk>
>>
>> I've scheduled the patch by Joakim Zhang:
>>
>>     9daed89ae8a3 can: flexcan: fix timeout when set small bitrate
>>
>> that doubles the timeout to 100.
> 
> Eh, ok, but that's not sufficient for the MPC8309 (I tried with 100 at
> first, but as I write the minimally working timeout value turns out to
> be about 140 us). Do you want me to send another patch on top of
> 9daed89ae8a3, or how should I interpret the above?

Can you propose an updated commit message for Joakim Zhang's patch?

https://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can.git/commit/?h=testing&id=9daed89ae8a3fc44ccd2b2bb9c3c4d3e3431904d

I'll add it by hand and increase the timeout to 250. Ok?

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
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