Re: omap cpufreq driver in multi-platform kernels

[Nishanth Menon <nm@ti.com>]

On 02:23-20130327, Paul Walmsley wrote:
> Hi
> 
> On Tue, 26 Mar 2013, Rob Herring wrote:
> 
> > The omap cpufreq driver causes problems in multi-platform kernels
> > because it unconditionally registers with the cpufreq core and does not
> > check sufficiently that it is running on an omap platform. So on a
> > kernel with highbank and omap drivers booted on highbank, the
> > cpufreq-cpu0 driver fails to init. Any suggestions for how to fix? For
> > DT this could just be several of_machine_is_compatible checks, but I'm
> > not really sure for non-DT. Converting the driver to a platform driver
> > would be another option.
> 
> We could move the
> 
> 	mpu_clk = clk_get(NULL, "cpufreq_ck");
> 
> down to omap_cpufreq_init(), and bail out early if the clock alias doesn't 
> exist.  (Presumably we'd also want to change the clock role name if we did 
> that, to something like "omap_cpufreq_ck".)
> 
> Experimental patch follows, comments welcome.
We should deprecate usage on omap-cpufreq driver eventually, instead go
towards embracing the SoC generic implementation of cpufreq-cpu0 driver
IMHO.
http://marc.info/?l=linux-omap&m=136371580826031&w=2
is the series to support cpufreq_cpu0 driver in DT based boot.
Would you think this approach is sane? 
> 
> 
> - Paul
> 
> From c1b4374d9cdcf59e0cbe93aa5a23335cb3e60798 Mon Sep 17 00:00:00 2001
> From: Paul Walmsley <paul@pwsan.com>
> Date: Tue, 26 Mar 2013 20:16:39 -0600
> Subject: [PATCH] EXPERIMENTAL: cpufreq: avoid loading the OMAP driver on
>  non-OMAP multiplatform targets
> 
> etc. etc.
> ---
>  arch/arm/mach-omap2/cclock2420_data.c |    2 +-
>  arch/arm/mach-omap2/cclock2430_data.c |    2 +-
>  arch/arm/mach-omap2/cclock3xxx_data.c |    2 +-
>  arch/arm/mach-omap2/cclock44xx_data.c |    2 +-
>  drivers/cpufreq/omap-cpufreq.c        |    8 ++++----
>  5 files changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm/mach-omap2/cclock2420_data.c b/arch/arm/mach-omap2/cclock2420_data.c
> index 0f0a97c..d4316e9 100644
> --- a/arch/arm/mach-omap2/cclock2420_data.c
> +++ b/arch/arm/mach-omap2/cclock2420_data.c
> @@ -1885,7 +1885,7 @@ static struct omap_clk omap2420_clks[] = {
>  	CLK(NULL,	"timer_32k_ck",	&func_32k_ck,	CK_242X),
>  	CLK(NULL,	"timer_sys_ck",	&sys_ck,	CK_242X),
>  	CLK(NULL,	"timer_ext_ck",	&alt_ck,	CK_242X),
> -	CLK(NULL,	"cpufreq_ck",	&virt_prcm_set,	CK_242X),
> +	CLK(NULL,	"omap_cpufreq_ck",	&virt_prcm_set,	CK_242X),
>  };
>  
>  
> diff --git a/arch/arm/mach-omap2/cclock2430_data.c b/arch/arm/mach-omap2/cclock2430_data.c
> index aed8f74..7c855b9 100644
> --- a/arch/arm/mach-omap2/cclock2430_data.c
> +++ b/arch/arm/mach-omap2/cclock2430_data.c
> @@ -2001,7 +2001,7 @@ static struct omap_clk omap2430_clks[] = {
>  	CLK(NULL,	"timer_32k_ck",  &func_32k_ck,   CK_243X),
>  	CLK(NULL,	"timer_sys_ck",	&sys_ck,	CK_243X),
>  	CLK(NULL,	"timer_ext_ck",	&alt_ck,	CK_243X),
> -	CLK(NULL,	"cpufreq_ck",	&virt_prcm_set,	CK_243X),
> +	CLK(NULL,	"omap_cpufreq_ck",	&virt_prcm_set,	CK_243X),
>  };
>  
>  static const char *enable_init_clks[] = {
> diff --git a/arch/arm/mach-omap2/cclock3xxx_data.c b/arch/arm/mach-omap2/cclock3xxx_data.c
> index 4579c3c..17dd82c 100644
> --- a/arch/arm/mach-omap2/cclock3xxx_data.c
> +++ b/arch/arm/mach-omap2/cclock3xxx_data.c
> @@ -3501,7 +3501,7 @@ static struct omap_clk omap3xxx_clks[] = {
>  	CLK(NULL,	"uart4_ick",	&uart4_ick_am35xx,	CK_AM35XX),
>  	CLK(NULL,	"timer_32k_ck",	&omap_32k_fck,  CK_3XXX),
>  	CLK(NULL,	"timer_sys_ck",	&sys_ck,	CK_3XXX),
> -	CLK(NULL,	"cpufreq_ck",	&dpll1_ck,	CK_3XXX),
> +	CLK(NULL,	"omap_cpufreq_ck",	&dpll1_ck,	CK_3XXX),
>  };
>  
>  static const char *enable_init_clks[] = {
> diff --git a/arch/arm/mach-omap2/cclock44xx_data.c b/arch/arm/mach-omap2/cclock44xx_data.c
> index 3d58f33..66b85e5 100644
> --- a/arch/arm/mach-omap2/cclock44xx_data.c
> +++ b/arch/arm/mach-omap2/cclock44xx_data.c
> @@ -1660,7 +1660,7 @@ static struct omap_clk omap44xx_clks[] = {
>  	CLK("4013a000.timer",	"timer_sys_ck",	&syc_clk_div_ck,	CK_443X),
>  	CLK("4013c000.timer",	"timer_sys_ck",	&syc_clk_div_ck,	CK_443X),
>  	CLK("4013e000.timer",	"timer_sys_ck",	&syc_clk_div_ck,	CK_443X),
> -	CLK(NULL,	"cpufreq_ck",	&dpll_mpu_ck,	CK_443X),
> +	CLK(NULL,	"omap_cpufreq_ck",	&dpll_mpu_ck,	CK_443X),
>  };
>  
>  int __init omap4xxx_clk_init(void)
> diff --git a/drivers/cpufreq/omap-cpufreq.c b/drivers/cpufreq/omap-cpufreq.c
> index 9128c07..d46caa5 100644
> --- a/drivers/cpufreq/omap-cpufreq.c
> +++ b/drivers/cpufreq/omap-cpufreq.c
> @@ -175,10 +175,6 @@ static int __cpuinit omap_cpu_init(struct cpufreq_policy *policy)
>  {
>  	int result = 0;
>  
> -	mpu_clk = clk_get(NULL, "cpufreq_ck");
> -	if (IS_ERR(mpu_clk))
> -		return PTR_ERR(mpu_clk);
> -
>  	if (policy->cpu >= NR_CPUS) {
>  		result = -EINVAL;
>  		goto fail_ck;
> @@ -254,6 +250,10 @@ static struct cpufreq_driver omap_driver = {
>  
>  static int __init omap_cpufreq_init(void)
>  {
> +	mpu_clk = clk_get(NULL, "omap_cpufreq_ck");
> +	if (IS_ERR(mpu_clk))
> +		return PTR_ERR(mpu_clk);
> +
>  	mpu_dev = get_cpu_device(0);
>  	if (!mpu_dev) {
>  		pr_warning("%s: unable to get the mpu device\n", __func__);
> -- 
> 1.7.10.4
> 
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-- 
Regards,
Nishanth Menon