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

On 08/26/2013 08:03 PM, Russell King - ARM Linux wrote:

On Mon, Aug 26, 2013 at 05:36:15PM +0300, Tero Kristo wrote:

quoted

On 08/03/2013 09:31 PM, Russell King - ARM Linux wrote:

quoted

On Fri, Aug 02, 2013 at 07:25:20PM +0300, Tero Kristo wrote:

quoted

+
+	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.)

Yeah, most of the OMAP clocks have been traditionally referenced in this 
way, they are using clk_get_sys and with dev=NULL. conn-id is mostly unique.

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.

In the legacy code, pretty much all the clocks are mapped through 
clk_get_sys(NULL, conn), and large amount of the drivers don't even have 
DT conversion in place yet. I am attempting to handle the cases where we 
don't have OF nodes.... yet at least, without converting everything to 
DT, and without causing regressions (also, I don't even pretend to be 
capable of testing all the potential drivers for this.) Some parts of 
the basic infra which are using clk_get_sys are pretty silly also, like 
the ocp_if parts of the hwmod, I haven't figured out yet how to convert 
that to DT.

Personally I don't mind causing a regressions here though, if I get 
approval for it from Tony.

-Tero