[PATCHv5 01/31] CLK: clkdev: add support for looking up clocks from DT

Russell King - ARM Linux linux at arm.linux.org.uk
Mon Aug 26 13:03:27 EDT 2013

On Mon, Aug 26, 2013 at 05:36:15PM +0300, Tero Kristo wrote:
> On 08/03/2013 09:31 PM, Russell King - ARM Linux wrote:
>> On Fri, Aug 02, 2013 at 07:25:20PM +0300, Tero Kristo wrote:
>>> +
>>> +	if (cl)
>>> +		return cl;
>>> +
>>> +	/* If clock was not found, attempt to look-up from DT */
>>> +	node = of_find_node_by_name(NULL, con_id);
>> This is utterly broken if you're looking up purely by a connection ID.
>> Please, go back and read clk_get()'s documentation in linux/clk.h.
>> It's spelt out very plainly there.
>> NAK.
> Hi Russell,
> After looking at this a bit more, it seems difficult to get rid of the  
> clk_get -> of_clk_get conversion, however based on this comment I am  
> somewhat stuck. Do you think it would be acceptable if I change the  
> implementation of this patch to work like this:

Firstly, for clk_get(), you don't need to do anything - clk_get() already
deals with DT, and if your DT is correct, it should already be returning
the appropriate clock(s).

I guess the problem here is clk_get_sys(), because that doesn't take a
struct device (and it doesn't take a struct device because it's used
from code where there is no struct device to use with it.)

If you have an OF node, what's wrong with using of_clk_get_by_name()?
If you don't have an OF node, how do you expect to find the clock in
the device tree, remembering that clocks are specific to devices, and
the 2nd argument to clk_get()/clk_get_sys() is not a unique identifier.

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