linux-kernel - Re: [PATCH v6 6/9] misc: smpro-errmon: Add Ampere's SMpro error monitor driver

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Message-ID: <YcXLGYWx4gYq/Y+J@sirena.org.uk>
Date:   Fri, 24 Dec 2021 13:28:57 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Quan Nguyen <quan@...amperecomputing.com>
Cc:     Joel Stanley <joel@....id.au>, Andrew Jeffery <andrew@...id.au>,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Rob Herring <robh+dt@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Jonathan Corbet <corbet@....net>, linux-hwmon@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-aspeed@...ts.ozlabs.org,
        openbmc@...ts.ozlabs.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Derek Kiernan <derek.kiernan@...inx.com>,
        Dragan Cvetic <dragan.cvetic@...inx.com>,
        Arnd Bergmann <arnd@...db.de>,
        Gustavo Pimentel <Gustavo.Pimentel@...opsys.com>,
        Open Source Submission <patches@...erecomputing.com>,
        Phong Vo <phong@...amperecomputing.com>,
        "Thang Q . Nguyen" <thang@...amperecomputing.com>
Subject: Re: [PATCH v6 6/9] misc: smpro-errmon: Add Ampere's SMpro error
 monitor driver

On Fri, Dec 24, 2021 at 11:13:49AM +0700, Quan Nguyen wrote:

> +static int read_i2c_block_data(struct i2c_client *client, u16 address, u16 length, u8 *data)
> +{
> +	unsigned char outbuf[MAX_READ_BLOCK_LENGTH];
> +	unsigned char inbuf[2];
> +	struct i2c_msg msgs[2];
> +	ssize_t ret;
> +
> +	inbuf[0] = (address & 0xff);
> +	inbuf[1] = length;
> +
> +	msgs[0].addr = client->addr;
> +	msgs[0].flags = client->flags & I2C_M_TEN;
> +	msgs[0].len = 2;
> +	msgs[0].buf = inbuf;
> +
> +	msgs[1].addr = client->addr;
> +	msgs[1].flags = (client->flags  & I2C_M_TEN) | I2C_M_RD;
> +	msgs[1].len = length;
> +	msgs[1].buf = outbuf;
> +
> +	ret = i2c_transfer(client->adapter, msgs, NUM_I2C_MESSAGES);
> +	if (ret < 0)

regmap already supports bulk data access so it's not clear why we
would open code this.  Given that this is a single I2C transfer
it's also unclear why we'd need to export the regmap lock - a
single I2C transfer is atomic at the bus level so the regmap lock
isn't providing any additional concurrency protection.

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