On 30 June 2014 14:49, Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote:
> On Mon, Jun 30, 2014 at 12:39:26PM +0200, Vincent Guittot wrote:
>> On 30 June 2014 12:29, Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx> wrote:
>> > On Mon, Jun 30, 2014 at 12:12:22PM +0200, Maxime Ripard wrote:
>> >> The Cortex-A7 and Cortex-A15 based SoCs need a clock-frequency property in the
>> >> topology code.
>> >>
>> >> Allow to use a clock to provide the same information.
>> >>
>> >> Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
>> >
>> > This looks fine to me, but I don't know this code. Maybe Vincent Guittot
>> > should be on the To: list (added)?
>>
>> Thanks
>
> Ah, sorry for that.
>
>>
>> >
>> >> ---
>> >> arch/arm/kernel/topology.c | 25 ++++++++++++++++++-------
>> >> 1 file changed, 18 insertions(+), 7 deletions(-)
>> >>
>> >> diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
>> >> index 9d853189028b..268443d88094 100644
>> >> --- a/arch/arm/kernel/topology.c
>> >> +++ b/arch/arm/kernel/topology.c
>> >> @@ -11,6 +11,7 @@
>> >> * for more details.
>> >> */
>> >>
>> >> +#include <linux/clk.h>
>> >> #include <linux/cpu.h>
>> >> #include <linux/cpumask.h>
>> >> #include <linux/export.h>
>> >> @@ -100,8 +101,8 @@ static void __init parse_dt_topology(void)
>> >> GFP_NOWAIT);
>> >>
>> >> for_each_possible_cpu(cpu) {
>> >> - const u32 *rate;
>> >> - int len;
>> >> + struct clk *clk;
>> >> + u32 rate = 0;
>> >>
>> >> /* too early to use cpu->of_node */
>> >> cn = of_get_cpu_node(cpu, NULL);
>> >> @@ -117,14 +118,24 @@ static void __init parse_dt_topology(void)
>> >> if (cpu_eff->compatible == NULL)
>> >> continue;
>> >>
>> >> - rate = of_get_property(cn, "clock-frequency", &len);
>> >> - if (!rate || len != 4) {
>> >> - pr_err("%s missing clock-frequency property\n",
>> >> - cn->full_name);
>> >> + clk = of_clk_get(cn, 0);
>> >> + if (!IS_ERR(clk))
>> >> + rate = clk_get_rate(clk);
>>
>> We need the max frequency as it will be used to weight the different
>> CPUs capacity. How do you ensure that the current clock rate is the
>> max one ?
>
> Hmm, the clock-frequency attribute in the ePAPR is defined at the
> current CPU frequency, not the max one.
What means current frequency in device tree when DVFS is involved ?
Vincent
>
> Maxime
>
> --
> Maxime Ripard, Free Electrons
> Embedded Linux, Kernel and Android engineering
> http://free-electrons.com
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