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

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Date:   Fri, 13 Jan 2023 12:03:41 -0600
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Charles Keepax <ckeepax@...nsource.cirrus.com>, vkoul@...nel.org,
        yung-chuan.liao@...ux.intel.com, sanyog.r.kale@...el.com,
        linux-kernel@...r.kernel.org, patches@...nsource.cirrus.com
Subject: Re: [PATCH 2/2] regmap: sdw: Remove 8-bit value size restriction



On 1/13/23 11:11, Mark Brown wrote:
> On Fri, Jan 13, 2023 at 10:57:39AM -0600, Pierre-Louis Bossart wrote:
> 
>> The change from reg_write/read_reg to write/read seems ok, what I was
>> asking about was the gather_write.
> 
>> +	.write = regmap_sdw_write,
>> +	.gather_write = regmap_sdw_gather_write,
>> +	.read = regmap_sdw_read,
> 
>> what happens if you only have .write and .read? What does the
>> .gather_write help with if you only use only address?
> 
> Like I said before it means that the core doesn't have to put the
> register in a linear buffer with the values, meaning it can avoid
> copying already formatted data around or allocating memory.

Ah ok, I read sideways and missed the pointer arithmetic in the write
implementation

return sdw_nwrite_no_pm(slave, addr, val_size - sizeof(addr), val +
sizeof(addr));

Thanks for the clarification.