On 25/05/18 11:36, Suzuki K Poulose wrote:
On 25/05/18 11:17, Julien Thierry wrote:
On 25/05/18 11:04, Suzuki K Poulose wrote:
On 25/05/18 10:49, Julien Thierry wrote:
Add a cpufeature indicating whether a cpu supports masking interrupts
by priority.
How is this different from the SYSREG_GIC_CPUIF cap ? Is it just
the description ?
More or less.
It is just to have an easier condition in the rest of the series.
Basically the PRIO masking feature is enabled if we have a GICv3 CPUIF
working *and* the option was selected at build time. Before this meant
that I was checking for the GIC_CPUIF cap inside #ifdefs (and putting
alternatives depending on that inside #ifdefs as well).
Having this as a separate feature feels easier to manage in the code.
It also makes it clearer at boot time that the kernel will be using
irq priorities (although I admit it was not the initial intention):
[ 0.000000] CPU features: detected: IRQ priority masking
But yes that new feature will be detected only if SYSREG_GIC_CPUIF
gets detected as well.
Well, you could always wrap the check like :
static inline bool system_has_irq_priority_masking(void)
{
return (IS_ENABLED(CONFIG_YOUR_CONFIG) &&
cpus_have_const_cap(HWCAP_SYSREG_GIC_CPUIF));
}
and use it everywhere.
Yes, but I can't use that in the asm parts that use alternatives and
would need to surround them in #ifdef... :\
The description could be statically changed to reflect based on the #ifdef.
static const struct arm64_cpu_capabilities arm64_features[] = {
{
#ifdef CONFIG_YOUR_CONFIG
.desc = "GIC System register CPU interface with IRQ priority
masking"
#else
.desc = "GIC system register CPU interface",
#endif
.capability = ARM64_HAS_SYSREG_GIC_CPUIF,
.type = ARM64_CPUCAP_SYSTEM_FEATURE,
.matches = has_useable_gicv3_cpuif,
.sys_reg = SYS_ID_AA64PFR0_EL1,
.field_pos = ID_AA64PFR0_GIC_SHIFT,
.sign = FTR_UNSIGNED,
.min_field_value = 1,
Cheers
Suzuki
--
Julien Thierry
