Re: [PATCH 2/2] regmap: sdw: Remove 8-bit value size restriction

[Pierre-Louis Bossart]

On 1/12/23 13:50, Mark Brown wrote:
> On Thu, Jan 12, 2023 at 12:43:46PM -0600, Pierre-Louis Bossart wrote:
>> On 1/12/23 12:14, Mark Brown wrote:
> 
>>> The regmap gather_write() operation allows the bus to take two buffers,
>>> one for the register and one for the value, rather than requiring the
>>> core combine everything into a single buffer (mainly useful for large
>>> transfers like firmware downloads).
> 
>> Right, but that's not supported in SoundWire. sdw_nwrite() will only
>> work with consecutive addresses - and the auto-increment is handled in
>> software, not hardware.
> 
> No, that's exactly what this is for.  It's for the *register address*
> being in a separate buffer, the data is then a sequence of consecutive
> register values.>
>> What's suggested here is to use the first element of reg_buf, which begs
>> the question how different this is from a regular write. If there was a
>> discontinuity in reg_buf then this wouldn't work at all.
> 
> reg_buf contains the address of exactly one register.

So what's the difference with a plain write() of N data?