linux-kernel - Re: [PATCH v4 12/19] cpufreq: cpufreq-cpu0: remove device tree parsing for cpu nodes

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Message-ID: <522EFAD1.4020709@arm.com>
Date:	Tue, 10 Sep 2013 11:56:17 +0100
From:	Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@....com>
To:	Shawn Guo <shawn.guo@...aro.org>
CC:	Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@....com>,
	Guennadi Liakhovetski <g.liakhovetski@....de>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Jonas Bonn <jonas@...thpole.se>,
	Michal Simek <monstr@...str.eu>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>
Subject: Re: [PATCH v4 12/19] cpufreq: cpufreq-cpu0: remove device tree parsing
 for cpu nodes

On 10/09/13 03:44, Shawn Guo wrote:
> On Mon, Sep 09, 2013 at 04:24:18PM +0100, Sudeep KarkadaNagesha wrote:
>> Hi Shawn,
>>
>> Ok. But I am bit suspicious about devm_clk_get(cpu_dev, NULL).
>> I don't understand completely as how the clock are registered(whether
>> with dev_id or with connection_id).
> 
> As the connection_id of devm_clk_get() call here is NULL, the clock
> lookup should be registered with a proper dev_id in clk_register_clkdev()
> call.  And that's what you have seen with imx and shmobile code.
> 
>
>> A quick grep revealed that i.mx and shmobile is using conection id while
>> registering.
> 
> They are using dev_id.
> 
Yes correct. I misunderstood, was expecting caller to pass dev and clk
layer extract dev_name so that even when device name is changed the clk
registration need not be changed.

>> If the clock is registered with connection id and retrieved
>> with cpu_dev(now dev_id is cpu0 and not cpufreq-cpu0), IIUC that would
>> break. If we pass pdev->dev for clk_get, it should be fine but again
>> IIUC it breaks highbank which gets all the information from DT.
> 
> If the clock lookup is from DT, we should be just fine, since it will
> work as long as the DT node with 'clocks' property (/cpus/cpu@0 in this
> case) is attached to the struct device pointer of devm_clk_get() call.
> 
This can be ignored if we are registering with "cpu0" as below in your
patch.

>> So only solution I can think of is to continue to have the code
>> assigning (&pdev->dev)->of_node with cpu device node which is not clean
>> and arguable as incorrect since there is no DT node for cpufreq-cpu0.
>> I don't have a strong opinion though.
>>
>> Let me know how would you like to fix this.
> 
> So we only need to change all clkdev registration to use "cpu0" as
> dev_id intstead of "cpufreq-cpu0.0", something like below.
> 
> And for imx, it should work even without the changes, because we have
> device tree lookup ready there, and those clk_register_clkdev() calls
> can just be removed now.  But I prefer to include the change and leave
> the cleanup to another patch for keeping the change log clear.
> 
Ok makes sense, do you want me to include this patch also as fix.
I can send a series to fix this if you OK:
1. Fix in cpufreq-cpu0
2. Fix in i.MX driver and platform file
3. Patch below

Regards,
Sudeep

> 
> ---8<----------
> 
> diff --git a/arch/arm/mach-imx/clk-imx27.c b/arch/arm/mach-imx/clk-imx27.c
> index c3cfa41..c6b40f3 100644
> --- a/arch/arm/mach-imx/clk-imx27.c
> +++ b/arch/arm/mach-imx/clk-imx27.c
> @@ -285,7 +285,7 @@ int __init mx27_clocks_init(unsigned long fref)
>  	clk_register_clkdev(clk[ata_ahb_gate], "ata", NULL);
>  	clk_register_clkdev(clk[rtc_ipg_gate], NULL, "imx21-rtc");
>  	clk_register_clkdev(clk[scc_ipg_gate], "scc", NULL);
> -	clk_register_clkdev(clk[cpu_div], NULL, "cpufreq-cpu0.0");
> +	clk_register_clkdev(clk[cpu_div], NULL, "cpu0");
>  	clk_register_clkdev(clk[emi_ahb_gate], "emi_ahb" , NULL);
>  
>  	mxc_timer_init(MX27_IO_ADDRESS(MX27_GPT1_BASE_ADDR), MX27_INT_GPT1);
> diff --git a/arch/arm/mach-imx/clk-imx51-imx53.c b/arch/arm/mach-imx/clk-imx51-imx53.c
> index 1a56a33..de1964c 100644
> --- a/arch/arm/mach-imx/clk-imx51-imx53.c
> +++ b/arch/arm/mach-imx/clk-imx51-imx53.c
> @@ -328,7 +328,7 @@ static void __init mx5_clocks_common_init(unsigned long rate_ckil,
>  	clk_register_clkdev(clk[ssi2_ipg_gate], NULL, "imx-ssi.1");
>  	clk_register_clkdev(clk[ssi3_ipg_gate], NULL, "imx-ssi.2");
>  	clk_register_clkdev(clk[sdma_gate], NULL, "imx35-sdma");
> -	clk_register_clkdev(clk[cpu_podf], NULL, "cpufreq-cpu0.0");
> +	clk_register_clkdev(clk[cpu_podf], NULL, "cpu0");
>  	clk_register_clkdev(clk[iim_gate], "iim", NULL);
>  	clk_register_clkdev(clk[dummy], NULL, "imx2-wdt.0");
>  	clk_register_clkdev(clk[dummy], NULL, "imx2-wdt.1");
> diff --git a/arch/arm/mach-shmobile/clock-r8a73a4.c b/arch/arm/mach-shmobile/clock-r8a73a4.c
> index 8ea5ef6..5bd2e85 100644
> --- a/arch/arm/mach-shmobile/clock-r8a73a4.c
> +++ b/arch/arm/mach-shmobile/clock-r8a73a4.c
> @@ -555,7 +555,7 @@ static struct clk_lookup lookups[] = {
>  	CLKDEV_CON_ID("pll2h",			&pll2h_clk),
>  
>  	/* CPU clock */
> -	CLKDEV_DEV_ID("cpufreq-cpu0",		&z_clk),
> +	CLKDEV_DEV_ID("cpu0",			&z_clk),
>  
>  	/* DIV6 */
>  	CLKDEV_CON_ID("zb",			&div6_clks[DIV6_ZB]),
> diff --git a/arch/arm/mach-shmobile/clock-sh73a0.c b/arch/arm/mach-shmobile/clock-sh73a0.c
> index 1942eae..c92c023 100644
> --- a/arch/arm/mach-shmobile/clock-sh73a0.c
> +++ b/arch/arm/mach-shmobile/clock-sh73a0.c
> @@ -616,7 +616,7 @@ static struct clk_lookup lookups[] = {
>  	CLKDEV_DEV_ID("smp_twd", &twd_clk), /* smp_twd */
>  
>  	/* DIV4 clocks */
> -	CLKDEV_DEV_ID("cpufreq-cpu0", &div4_clks[DIV4_Z]),
> +	CLKDEV_DEV_ID("cpu0", &div4_clks[DIV4_Z]),
>  
>  	/* DIV6 clocks */
>  	CLKDEV_CON_ID("vck1_clk", &div6_clks[DIV6_VCK1]),
> 
> 


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