[U-Boot] [PATCH] cmd_i2c: Provide option for bulk 'i2c write' in one transaction

[Heiko Schocher]

Hello Lubomir,

Am 28.01.2015 09:32, schrieb Lubomir Popov:
> Hi Heiko,
>
>> Hello Lubomir,
>>
>> Am 24.11.2014 17:00, schrieb Lubomir Popov:
>>> I2C chips do exist that require a write of some multi-byte data to occur in
>>> a single bus transaction (aka atomic transfer), otherwise either the write
>>> does not come into effect at all, or normal operation of internal circuitry
>>> cannot be guaranteed. The current implementation of the 'i2c write' command
>>> (transfer of multiple bytes from a memory buffer) in fact performs a separate
>>> transaction for each byte to be written and thus cannot support such types of
>>> I2C slave devices.
>>>
>>> This patch provides an alternative by allowing 'i2c write' to execute the
>>> write transfer of the given number of bytes in a single bus transaction if
>>> CONFIG_SYS_I2C_BULK_WRITE is defined in the board header (otherwise the old
>>> method shall compile).
>>>
>>> Signed-off-by: Lubomir Popov <l-popov at ti.com>
>>> ---
>>>    common/cmd_i2c.c |   15 ++++++++++++++-
>>>    1 file changed, 14 insertions(+), 1 deletion(-)
>>
>> Could you rebase your patch against current mainline, please?
>> As we have now DM in i2c subsystem your patch does not apply clean
>> anymore ... thanks!
>
> It looks like you are referring V1 of the patch here. The correct
> version is V2 (http://patchwork.ozlabs.org/patch/415117/). If it
> doesn't apply as well, I shall try to find some time to fix it.

Sorry, was the wrong EMail I replied ... but the v2 does not
apply to current mainline. If you can fix it, that would be great.

Thanks!

bye,
Heiko
>
> Thanks,
> Lubo
>
>>
>> bye,
>> Heiko
>>>
>>> diff --git a/common/cmd_i2c.c b/common/cmd_i2c.c
>>> index 3a75f94..7116458 100644
>>> --- a/common/cmd_i2c.c
>>> +++ b/common/cmd_i2c.c
>>> @@ -280,10 +280,22 @@ static int do_i2c_write(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[
>>>    		return cmd_usage(cmdtp);
>>>
>>>    	/*
>>> -	 * Length is the number of objects, not number of bytes.
>>> +	 * Length is the number of bytes.
>>>    	 */
>>>    	length = simple_strtoul(argv[4], NULL, 16);
>>>
>>> +#if defined(CONFIG_SYS_I2C_BULK_WRITE)
>>> +	/*
>>> +	 * Write all bytes in a single I2C transaction. If the target
>>> +	 * device is an EEPROM, it is your responsibility to not cross
>>> +	 * a page bounady.
>>> +	 */
>>> +	if (i2c_write(chip, devaddr, alen, memaddr, length) != 0) {
>>> +		puts("Error writing to the chip.\n");
>>> +		return 1;
>>> +	}
>>> +#else
>>> +	/* Perform <length> separate write transactions of one byte each */
>>>    	while (length-- > 0) {
>>>    		if (i2c_write(chip, devaddr++, alen, memaddr++, 1) != 0) {
>>>    			puts("Error writing to the chip.\n");
>>> @@ -296,6 +308,7 @@ static int do_i2c_write(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[
>>>    		udelay(11000);
>>>    #endif
>>>    	}
>>> +#endif
>>>    	return 0;
>>>    }
>>>
>>
>> --
>> DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
>> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
>>
>
>

-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany