linux-kernel - Re: [RFD] voltage/current regulator consumer interface

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Date:	Tue, 21 Apr 2009 16:54:51 +0300
From:	Mike Rapoport <mike@...pulab.co.il>
To:	Mark Brown <broonie@...ena.org.uk>
CC:	Liam Girdwood <lrg@...mlogic.co.uk>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFD] voltage/current regulator consumer interface

Mark Brown wrote:
> On Tue, Apr 21, 2009 at 03:00:41PM +0300, Mike Rapoport wrote:
> 
>> I've managed to create some preliminary "line-consumer" driver. I don't really
>> like the name, but I couldn't think of something better and "virtual" is
>> already taken :)
> 
> "userspace" or "user"?  The goal here is to let userspace applications
> be consumers.

I don't quite understand your intention here. Do you mean that it would bebetter
to use a character device rather than sysfs?

>> +static ssize_t set_state(struct device *dev, struct device_attribute *attr,
>> +			 const char *buf, size_t count)
>> +{
>> +	struct line_consumer_data *data = dev_get_drvdata(dev);
>> +	bool enabled;
>> +	int ret;
>> +
>> +	/*
>> +	 * sysfs_streq() doesn't need the \n's, but we add them so the strings
>> +	 * will be shared with show_state(), above.
>> +	 */
>> +	if (sysfs_streq(buf, "enabled\n") == 0)
>> +		enabled = true;
>> +	else if (sysfs_streq(buf, "disabled\n") == 0)
>> +		enabled = false;
> 
> I'd be inclined to also accept 1 and 0 here.
> 
>> +static DEVICE_ATTR(name, 0444, show_name, NULL);
>> +static DEVICE_ATTR(state, 0666, show_state, set_state);
> 
> Permissions for set_state() should probably be tighter?
> 
>> +	for (i = 0; i < ARRAY_SIZE(attributes); i++) {
>> +		ret = device_create_file(&pdev->dev, attributes[i]);
>> +		if (ret != 0)
>> +			goto err_create_attrs;
>> +	}
> 
> device_add_attributes()?
> 
>> +	if (pdata->init_on)
>> +		ret = regulator_bulk_enable(drvdata->num_supplies,
>> +					    drvdata->supplies);
>> +	else
>> +		ret = regulator_bulk_disable(drvdata->num_supplies,
>> +					     drvdata->supplies);
> 
> The disable case will lead to unbalanced enables and disables, loosing
> a reference to the supply.  Just don't do anything if the supplies
> should not be enabled.
> 
>> +static int regulator_line_consumer_remove(struct platform_device *pdev)
>> +{
>> +	struct line_consumer_data *drvdata = platform_get_drvdata(pdev);
>> +	int i;
>> +
>> +	for (i = 0; i < ARRAY_SIZE(attributes); i++)
>> +		device_remove_file(&pdev->dev, attributes[i]);
>> +
>> +	regulator_bulk_free(drvdata->num_supplies, drvdata->supplies);
>> +	kfree(drvdata->supplies);
>> +	kfree(drvdata);
>> +
>> +	return 0;
>> +}
> 
> Hrm.  You probably want to disable the supplies if you weren't using
> them here.
> --
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> 

-- 
Sincerely yours,
Mike.



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