Hi Heiko,
2015-04-21 23:56 GMT+09:00 Heiko Stübner <heiko@xxxxxxxxx>:
> Am Dienstag, 21. April 2015, 16:21:27 schrieb Masahiro Yamada:
>> Initial commit for a new SoC family, UniPhier, developed by
>> Socionext Inc. (formerly, System LSI Business Division of
>> Panasonic Corporation).
>>
>> This commit includes a minimal set of components for booting the
>> kernel, including SMP support.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
>> ---
>
> [...]
>
>> +static int uniphier_boot_secondary(unsigned int cpu,
>> + struct task_struct *idle)
>> +{
>> + struct regmap *sbcm_regmap;
>> + int ret;
>> +
>> + sbcm_regmap = syscon_regmap_lookup_by_compatible(
>> + "socionext,uniphier-system-bus-controller-misc");
>> + if (IS_ERR(sbcm_regmap)) {
>> + pr_err("failed to regmap system-bus-controller-misc\n");
>> + return PTR_ERR(sbcm_regmap);
>> + }
>> +
>> + ret = regmap_write(sbcm_regmap, 0x1208,
>> + virt_to_phys(uniphier_secondary_startup));
>> + if (!ret)
>> + asm("sev"); /* wake up secondary CPU */
>> +
>> + return ret;
>> +}
>> +
>> +struct smp_operations uniphier_smp_ops __initdata = {
>> + .smp_prepare_cpus = uniphier_smp_prepare_cpus,
>> + .smp_boot_secondary = uniphier_boot_secondary,
>> +};
>
> this is more of a drive-by comment, but you're doing the syscon lookup on
> every boot of a core, which includes walking big parts of the devicetree every
> time.
>
> Is there anything speaking against doing this once in a .smp_prepare_cpus
> callback?
Not really.
I fixed this in v5.
Thanks for reviewing my patch!
--
Best Regards
Masahiro Yamada
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