Re: [PATCH V3 1/2] ARM: OMAP3+: use cpu0-cpufreq driver in device tree supported boot

[Nishanth Menon <nm@ti.com>]

On 10:43-20130404, Rajendra Nayak wrote:
> On Thursday 04 April 2013 08:22 AM, Nishanth Menon wrote:
> > On 11:47-20130403, Kevin Hilman wrote:
> >> Nishanth Menon <nm@ti.com> writes:
> >>
> > [...]
> >>> diff --git a/arch/arm/mach-omap2/board-generic.c b/arch/arm/mach-omap2/board-generic.c
> >>> index afa509a..5b147ef 100644
> >>> --- a/arch/arm/mach-omap2/board-generic.c
> >>> +++ b/arch/arm/mach-omap2/board-generic.c
> >>> @@ -49,6 +49,11 @@ static void __init omap_generic_init(void)
> >>>  		omap4_panda_display_init_of();
> >>>  	else if (of_machine_is_compatible("ti,omap4-sdp"))
> >>>  		omap_4430sdp_display_init_of();
> >>> +
> >>> +	if (IS_ENABLED(CONFIG_GENERIC_CPUFREQ_CPU0)) {
> >>> +		struct platform_device_info devinfo = { .name = "cpufreq-cpu0", };
> >>> +		platform_device_register_full(&devinfo);
> >>> +	}
> >>
> >> Rather than adding new clkdev nodes below, how about using clk add_alias
> >> here?
> > Thanks for pointing this out, I spend some time implementing such a
> > scheme and following is my opinion:
> > 
> > Summary:
> > There is one major problem which forces us to introduce this "clock
> > hack" - clock nodes are not in device tree yet. Yes, clock add alias
> 
> There's already a patch floating around for this..
> https://lkml.org/lkml/2013/4/2/84
Not really. Try on OMAP4 PandaBoard:
Based on
git://git.kernel.org/pub/scm/linux/kernel/git/bcousson/linux-omap-dt.git
for_3.10/dts  d114294 ARM: dts: AM33XX: Corrects typo in interrupt field in SPI node
+ the patch https://patchwork.kernel.org/patch/2335671/ applied
Pandaboard 4 Log: http://pastebin.com/qsdsbv7p
The Patch does not even work, unless there is un-documented patch
dependencies!

Secondly, even if it did work, it would still continue to need yet another
hack[1] - I am agree with Tony in his discussion in
http://marc.info/?t=136370325600009&r=1&w=2

*if* we are moving clock to DT, we should move the data to DT as well -
similar to what other platforms do - highbank as far as i can quickly
see. (drivers/clk/clk-highbank.c and arch/arm/boot/dts/ecx-common.dtsi
as examples). Clk alias might have been a solution, but in this case,
clk add alias (as I indicated in this thread is not really worth the
effort for the mess of code it creates for cpu clock).

[1]
diff --git a/arch/arm/boot/dts/omap4.dtsi b/arch/arm/boot/dts/omap4.dtsi
index dd8f58f..9282b4c 100644
--- a/arch/arm/boot/dts/omap4.dtsi
+++ b/arch/arm/boot/dts/omap4.dtsi
@@ -635,4 +635,9 @@
 			ti,has-mailbox;
 		};
 	};
+
+	dpll_mpu: scrmclks {
+		compatible = "ti,omap4-clock";
+		#clock-cells = <1>;
+	};
 };
diff --git a/arch/arm/boot/dts/omap443x.dtsi b/arch/arm/boot/dts/omap443x.dtsi
index cccf39a..1587a5f 100644
--- a/arch/arm/boot/dts/omap443x.dtsi
+++ b/arch/arm/boot/dts/omap443x.dtsi
@@ -21,6 +21,8 @@
 				800000  1313000
 				1008000 1375000
 			>;
+			clocks = <&dpll_mpu>;
+			clock-names = "cpu";
 			clock-latency = <300000>; /* From legacy driver */
 		};
 	};
diff --git a/arch/arm/mach-omap2/board-generic.c b/arch/arm/mach-omap2/board-generic.c
index afa509a..5b147ef 100644
--- a/arch/arm/mach-omap2/board-generic.c
+++ b/arch/arm/mach-omap2/board-generic.c
@@ -49,6 +49,11 @@ static void __init omap_generic_init(void)
 		omap4_panda_display_init_of();
 	else if (of_machine_is_compatible("ti,omap4-sdp"))
 		omap_4430sdp_display_init_of();
+
+	if (IS_ENABLED(CONFIG_GENERIC_CPUFREQ_CPU0)) {
+		struct platform_device_info devinfo = { .name = "cpufreq-cpu0", };
+		platform_device_register_full(&devinfo);
+	}
 }
 
 #ifdef CONFIG_SOC_OMAP2420
diff --git a/arch/arm/mach-omap2/cclock44xx_data.c b/arch/arm/mach-omap2/cclock44xx_data.c
index a93617b..ba4562a 100644
--- a/arch/arm/mach-omap2/cclock44xx_data.c
+++ b/arch/arm/mach-omap2/cclock44xx_data.c
@@ -1675,6 +1675,7 @@ static struct clk *dt_clks[] = {
 	&auxclk3_ck,
 	&auxclk4_ck,
 	&auxclk5_ck,
+	&dpll_mpu_ck,
 };
 
 static struct clk_onecell_data clock_data;

-- 
Regards,
Nishanth Menon