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

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Message-ID: <Y8BOCpXyOyF3igfG@sirena.org.uk>
Date:   Thu, 12 Jan 2023 18:14:34 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
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 Thu, Jan 12, 2023 at 11:38:38AM -0600, Pierre-Louis Bossart wrote:

> > +static int regmap_sdw_gather_write(void *context,
> > +				   const void *reg_buf, size_t reg_size,
> > +				   const void *val_buf, size_t val_size)
> >  {
> >  	struct device *dev = context;
> >  	struct sdw_slave *slave = dev_to_sdw_dev(dev);
> > -	int read;
> > +	u32 addr = le32_to_cpu(*(const __le32 *)reg_buf);

> what's the difference between regmap_sdw_write() and
> regmap_sdw_gather_write()? Seems to me that it's the same functionality
> of writing at consecutive addresses. It's not a true 'gather' in the
> sense that only the first address is used?

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).

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