netdev - Re: [net 05/11] can: flexcan: flexcan_chip_freeze(): fix chip freeze for missing bitrate

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Date:   Tue, 16 Mar 2021 10:12:16 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Angelo Dureghello <angelo@...nel-space.org>, netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, linux-can@...r.kernel.org,
        kernel@...gutronix.de
Subject: Re: [net 05/11] can: flexcan: flexcan_chip_freeze(): fix chip freeze
 for missing bitrate

On 3/16/21 10:02 AM, Angelo Dureghello wrote:
> Hi all,
> 
> On 16/03/21 9:20 AM, Marc Kleine-Budde wrote:
>> From: Angelo Dureghello <angelo@...nel-space.org>
>>
>> For cases when flexcan is built-in, bitrate is still not set at
>> registering. So flexcan_chip_freeze() generates:
>>
>> [    1.860000] *** ZERO DIVIDE ***   FORMAT=4
>> [    1.860000] Current process id is 1
>> [    1.860000] BAD KERNEL TRAP: 00000000
>> [    1.860000] PC: [<402e70c8>] flexcan_chip_freeze+0x1a/0xa8
>>
>> To allow chip freeze, using an hardcoded timeout when bitrate is still
>> not set.
>>
>> Fixes: ec15e27cc890 ("can: flexcan: enable RX FIFO after FRZ/HALT valid")
>> Link: https://lore.kernel.org/r/20210315231510.650593-1-angelo@kernel-space.org
>> Signed-off-by: Angelo Dureghello <angelo@...nel-space.org>
>> [mkl: use if instead of ? operator]
>> Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
>> ---
>>  drivers/net/can/flexcan.c | 8 +++++++-
>>  1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
>> index 134c05757a3b..57f3635ad8d7 100644
>> --- a/drivers/net/can/flexcan.c
>> +++ b/drivers/net/can/flexcan.c
>> @@ -697,9 +697,15 @@ static int flexcan_chip_disable(struct flexcan_priv *priv)
>>  static int flexcan_chip_freeze(struct flexcan_priv *priv)
>>  {
>>  	struct flexcan_regs __iomem *regs = priv->regs;
>> -	unsigned int timeout = 1000 * 1000 * 10 / priv->can.bittiming.bitrate;
>> +	unsigned int timeout;
>> +	u32 bitrate = priv->can.bittiming.bitrate;
>>  	u32 reg;
>>  
>> +	if (bitrate)
>> +		timeout = 1000 * 1000 * 10 / bitrate;
>> +	else
>> +		timeout = FLEXCAN_TIMEOUT_US / 10;
>> +
>>  	reg = priv->read(&regs->mcr);
>>  	reg |= FLEXCAN_MCR_FRZ | FLEXCAN_MCR_HALT;
>>  	priv->write(reg, &regs->mcr);
> 
> ?
> 
> Just curious, what's the issue with my "?" ?

Personal preference and readability.

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
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Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |



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