[PATCH 33/33] ARM: i.MX6: implement clocks using common clock framework

[Richard Zhao]

On Thu, Apr 26, 2012 at 10:04:41AM +0200, Sascha Hauer wrote:
> On Thu, Apr 26, 2012 at 09:14:13AM +0200, Sascha Hauer wrote:
> > On Thu, Apr 26, 2012 at 02:57:02PM +0800, Richard Zhao wrote:
> > > On Thu, Apr 26, 2012 at 08:41:50AM +0200, Sascha Hauer wrote:
> > > > On Thu, Apr 26, 2012 at 10:48:38AM +0800, Richard Zhao wrote:
> > > > > The below code is removed from mx6q_clocks_init implicitly.
> > > > > Why? If it's reasonable, it needs to be on a separate patch too.
> > > > > 
> > > > > clk_set_rate(&usdhc1_clk, 49500000);
> > > > > clk_set_rate(&usdhc2_clk, 49500000);
> > > > > clk_set_rate(&usdhc3_clk, 49500000);
> > > > > clk_set_rate(&usdhc4_clk, 49500000);
> > > > 
> > > > Can't say anything to these, probably Shawn has simply lost them while
> > > > porting.
> > > > 
> > > > > 
> > > > > clk_set_parent(&cko1_clk, &ahb_clk);
> > > > 
> > > > Why this? The cko pin has different usecases on each board, mostly I
> > > > think for debugging. We shouldn't touch it here.
> > > clko1's used by audio codec on many boards.
> > > Do you/Shawn think I can add board specific code here with
> > > of_machine_is_compatible? I need to add audio codec clkdev. Other places
> > > can not get clk pointers.
> > 
> > Agreed that we need something to adjust/reparent this clock, but adding
> > board specific code to this file is not the right thing to do.
> 
> BTW I generally wonder how a board (or SoC code) can reparent clocks if
> needed. At the moment we need
> 
> 	clk_get_sys(mux);
> 	clk_get_sys(new_parent);
> 	clk_set_parent(mux, new_parent);
> 
> The above needs error checking and we need a clkdev for all clocks we want
> to reparent + a clkdev for all possible parents.
> 
> All this together makes reparenting in practice quite cumbersome. I have
> the hope that future additions to the clock framework will make this
> easier.
Maybe dts file can describe the set-rate/reparent information. It's
sometimes board specific.
For reparent switching at runtime, we can expose the clk, and use such
cumbersome way.

Richard
> 
> Sascha
> 
> -- 
> Pengutronix e.K.                           |                             |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
>