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

[Lubomir Popov]

Hi Heiko,

> 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.
OK. Do you have a deadline to finish the I2C updates? I'm really
very busy right now and am not sure if I shall manage with this
before the end of the week, but can try...

Regards,
Lubo

>
> 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
>