linux-kernel - Re: [PATCH] cmpc_acpi: Added support for Classmate PC ACPI devices.

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Message-Id: <20090929130522.ecf4d5ec.akpm@linux-foundation.org>
Date:	Tue, 29 Sep 2009 13:05:22 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Thadeu Lima de Souza Cascardo <cascardo@...oscopio.com>
Cc:	linux-kernel@...r.kernel.org, len.brown@...el.com, don@...t.com.br,
	linux-acpi@...r.kernel.org, cascardo@...oscopio.com
Subject: Re: [PATCH] cmpc_acpi: Added support for Classmate PC ACPI devices.

On Mon, 28 Sep 2009 22:38:00 -0300
Thadeu Lima de Souza Cascardo <cascardo@...oscopio.com> wrote:

> This add supports for devices like keyboard, backlight, tablet and
> accelerometer.
> 
> This work is supported by International Syst S/A.
> 

I need to have a big whine about the coding style.

> +static acpi_status cmpc_start_accel(acpi_handle handle)
> +{
> +	union acpi_object param[2];
> +	struct acpi_object_list input;
> +	acpi_status status;
> +	param[0].type = ACPI_TYPE_INTEGER;
> +	param[0].integer.value = 0x3;
> +	param[1].type = ACPI_TYPE_INTEGER;
> +	input.count = 2;
> +	input.pointer = param;
> +	status = acpi_evaluate_object(handle, "ACMD", &input, NULL);
> +	return status;
> +}

To the jaded kernel developer's eye, this is quite hard to read.  Every
function here squishes the declarations of the locals up against the
start of the code.  It's a small thing, but this:

static acpi_status cmpc_start_accel(acpi_handle handle)
{
	union acpi_object param[2];
	struct acpi_object_list input;
	acpi_status status;

	param[0].type = ACPI_TYPE_INTEGER;
	param[0].integer.value = 0x3;
	param[1].type = ACPI_TYPE_INTEGER;
	input.count = 2;
	input.pointer = param;
	status = acpi_evaluate_object(handle, "ACMD", &input, NULL);
	return status;
}

puts a smile on our faces.

>
> ...
>
> +static ssize_t cmpc_accel_sense_store(struct device *dev,
> +				      struct device_attribute *attr,
> +				      const char *buf, size_t count)
> +{
> +	struct acpi_device *acpi;
> +	int sense;
> +	acpi = to_acpi_device(dev);
> +	if (sscanf(buf, "%d", &sense) <= 0)
> +		return -EINVAL;
> +	cmpc_accel_set_sense(acpi->handle, sense);
> +	return strnlen(buf, count);
> +}

This will treat input of the form "42foo" as a valid decimal number. 
That's a bit sloppy.  Can we use strict_strtoul() here?

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