From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sylwester Nawrocki <s.nawrocki@samsung.com>
Date: Mon, 08 Apr 2013 15:20:35 +0000
Subject: Re: [PATCH v6 1/7] media: V4L2: add temporary clock helpers
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To: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: Sylwester Nawrocki <sylvester.nawrocki@gmail.com>, linux-media@vger.kernel.org, Laurent Pinchart <laurent.pinchart@ideasonboard.com>, Hans Verkuil <hverkuil@xs4all.nl>, Sylwester Nawrocki <s.nawrocki@samsung.com>, linux-sh@vger.kernel.org, Magnus Damm <magnus.damm@gmail.com>, Sakari Ailus <sakari.ailus@iki.fi>, Prabhakar Lad <prabhakar.lad@ti.com>

On 04/08/2013 12:36 PM, Guennadi Liakhovetski wrote:
> On Mon, 18 Mar 2013, Sylwester Nawrocki wrote:
> 
> [snip]
> 
>>> +unsigned long v4l2_clk_get_rate(struct v4l2_clk *clk)
>>> +{
>>> +	if (!clk->ops->get_rate)
>>> +		return -ENOSYS;
>>
>> I guess we should just WARN if this callback is null and return 0
>> or return value type of this function needs to be 'long'. Otherwise
>> we'll get insanely large frequency value by casting this error code
>> to unsigned long.
> 
> Comparing to the CCF: AFAICS, they do the same, you're supposed to use 
> IS_ERR_VALUE() on the clock rate, obtained from clk_get_rate().

Hmm, that might work. Nevertheless I consider that a pretty horrible
pattern. I couldn't find any references to IS_ERR_VALUE in the clock
code though. Only that 0 is returned when clk is NULL.

Regards,
Sylwester