Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 23 Apr 2020 15:45:29 +0100
From:   Mark Brown <broonie@kernel.org>
To:     AceLan Kao <acelan.kao@canonical.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Aaron Sierra <asierra@xes-inc.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] regmap-i2c: add 16 bits register width support
Message-ID: <20200423144529.GM4808@sirena.org.uk>
References: <20200423085857.93684-1-acelan.kao@canonical.com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
        protocol="application/pgp-signature"; boundary="EE8jvUPYYQjJtG7J"
Content-Disposition: inline
In-Reply-To: <20200423085857.93684-1-acelan.kao@canonical.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


--EE8jvUPYYQjJtG7J
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline

On Thu, Apr 23, 2020 at 04:58:57PM +0800, AceLan Kao wrote:
> This allows to access data with 16 bits register width
> via i2c smbus block functions.

> The implementation is inspired by below commit
> https://patchwork.ozlabs.org/patch/545292/

Do you actually have a system that needs this or is it just being
implemented for completeness?  The patch you link to mentions that there
are correctness issues with this implementation.

Please include human readable descriptions of things like commits and
issues being discussed in e-mail in your mails, this makes them much
easier for humans to read especially when they have no internet access.
I do frequently catch up on my mail on flights or while otherwise
travelling so this is even more pressing for me than just being about
making things a bit easier to read.

> @@ -255,6 +312,10 @@ static const struct regmap_bus *regmap_get_i2c_bus(struct i2c_client *i2c,
>  		 i2c_check_functionality(i2c->adapter,
>  					 I2C_FUNC_SMBUS_I2C_BLOCK))
>  		return &regmap_i2c_smbus_i2c_block;
> +	else if (config->val_bits == 8 && config->reg_bits == 16 &&
> +		i2c_check_functionality(i2c->adapter,
> +					I2C_FUNC_SMBUS_I2C_BLOCK))
> +		return &regmap_i2c_smbus_i2c_block_reg16;

OTOH we'll only use it if the device wouldn't otherwise work so I'm not
sure that it's any worse than just hoping the bus is uncontested,
hopefully system designers have taken this into account when building
systems without real I2C controllers.

--EE8jvUPYYQjJtG7J
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----

iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl6hqggACgkQJNaLcl1U
h9DIqgf+O6MUgn8IRhVjKqiNm14EY05T45nx9Glldr42oSPuanv/Og8adXetxcNf
IJP1xEihOrPMS7DZJl1Vc/jbJR3SMX0cbhDNxQTjXV00R02YeHDieCy/991CaNrY
ZwaOEoVjguOHCs9Z5f9jRGTUd2FZ5uLNgpssj3rS4Jugs+GUka5FFQGQMs9ckh1S
fynMgFbn1rsAsSsMnjHSUwgSxp/6ZXsXhnUt7twiQf0B7aW9m7NjsZduXE8LRpJA
hJC5Aj+Xrm0QqtzUmeb/Us5t5IYoE/u3DXLDfghbHkpzeLki86Vxw9m0IuAm0rMP
XhZyIBBMKsTUakQhqffh/aqMFEvckA==
=nI9G
-----END PGP SIGNATURE-----

--EE8jvUPYYQjJtG7J--