Re: [PATCH 1/3] can: flexcan.c: Correctly initialize mailboxes

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 09/02/2014 01:38 PM, Marc Kleine-Budde wrote:

>> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
>> index 3f21142..f028c5d 100644
>> --- a/drivers/net/can/flexcan.c
>> +++ b/drivers/net/can/flexcan.c
>> @@ -62,7 +62,7 @@
>>  #define FLEXCAN_MCR_BCC			BIT(16)
>>  #define FLEXCAN_MCR_LPRIO_EN		BIT(13)
>>  #define FLEXCAN_MCR_AEN			BIT(12)
>> -#define FLEXCAN_MCR_MAXMB(x)		((x) & 0xf)
>> +#define FLEXCAN_MCR_MAXMB(x)		((x) & 0x1f)
>>  #define FLEXCAN_MCR_IDAM_A		(0 << 8)
>>  #define FLEXCAN_MCR_IDAM_B		(1 << 8)
>>  #define FLEXCAN_MCR_IDAM_C		(2 << 8)
>> @@ -735,9 +735,11 @@ static int flexcan_chip_start(struct net_device *dev)
>>  	 *
>>  	 */
>>  	reg_mcr = flexcan_read(&regs->mcr);
>> +	reg_mcr &= ~FLEXCAN_MCR_MAXMB(0xff);
>>  	reg_mcr |= FLEXCAN_MCR_FRZ | FLEXCAN_MCR_FEN | FLEXCAN_MCR_HALT |
>>  		FLEXCAN_MCR_SUPV | FLEXCAN_MCR_WRN_EN |
>> -		FLEXCAN_MCR_IDAM_C | FLEXCAN_MCR_SRX_DIS;
>> +		FLEXCAN_MCR_IDAM_C | FLEXCAN_MCR_SRX_DIS |
>> +		FLEXCAN_MCR_MAXMB(FLEXCAN_TX_BUF_ID);
>>  	netdev_dbg(dev, "%s: writing mcr=0x%08x", __func__, reg_mcr);
>>  	flexcan_write(reg_mcr, &regs->mcr);
>>  
>> Eh! This looks wrong! The MAXMB field is 7 bits wide according to the
>> reference manual (bits 0-6)... but the reset default value is supposed to be
> 
> ...according to the imx6 reference manual. The size of the MAXMB field
> depends on the actual IP version.

On mcf5213 (some old coldfire, not supported by this driver)
it's 4 bit wide.
On mx25, mx28, mx53 it's 6 bits wide.
On mx6{q,sdl}, vf610 it's 7 bits wide.
I'm not sure about the powerpc based cores as I don't have the data sheets.

I cannot find a data sheet, where it has a width of 5 bit.

I'll prepare a patch to fix it.

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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