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

[Heiko Schocher]

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!

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;
>   }
>

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