Hi Sudeep,
Couple of comments inline...
On Tue, Aug 13, 2013 at 06:29:42PM +0100, Sudeep KarkadaNagesha wrote:
> From: Sudeep KarkadaNagesha <sudeep.karkadanage...@arm.com>
>
> This patch configures the event stream frequency and enables it.
> It also adds the hwcaps as well as compat-specific definitions to
> the user to detect this event stream feature.
>
> Cc: Catalin Marinas <catalin.mari...@arm.com>
> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieral...@arm.com>
> Signed-off-by: Will Deacon <will.dea...@arm.com>
> [sudeep: moving ARM/ARM64 changes into separate patches]
> Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanage...@arm.com>
> ---
> arch/arm64/include/asm/arch_timer.h | 12 ++++++++++--
> arch/arm64/include/asm/hwcap.h | 4 +++-
> arch/arm64/include/uapi/asm/hwcap.h | 1 +
> arch/arm64/kernel/setup.c | 1 +
> 4 files changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/include/asm/arch_timer.h
> b/arch/arm64/include/asm/arch_timer.h
> index 69f5c8e..43f322a 100644
> --- a/arch/arm64/include/asm/arch_timer.h
> +++ b/arch/arm64/include/asm/arch_timer.h
> @@ -106,14 +106,22 @@ static inline void arch_counter_set_user_access(int
> divider)
> /* Disable user access to the timers and the physical counter. */
> cntkctl &= ~(ARCH_TIMER_USR_PT_ACCESS_EN
> | ARCH_TIMER_USR_VT_ACCESS_EN
> + | ARCH_TIMER_EVT_TRIGGER_MASK
> | ARCH_TIMER_USR_PCT_ACCESS_EN);
>
> - /* Enable user access to the virtual counter. */
> - cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;
> + /* Enable event stream and user access to the virtual counter */
> + cntkctl |= (divider << ARCH_TIMER_EVT_TRIGGER_SHIFT)
> + | ARCH_TIMER_VIRT_EVT_EN
> + | ARCH_TIMER_USR_VCT_ACCESS_EN;
>
> asm volatile("msr cntkctl_el1, %0" : : "r" (cntkctl));
> }
>
> +static inline void arch_timer_set_hwcap_evtstrm(void)
> +{
> + elf_hwcap |= HWCAP_EVTSTRM;
> +}
> +
> static inline u64 arch_counter_get_cntvct(void)
> {
> u64 cval;
> diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
> index 6d4482f..effd8f9 100644
> --- a/arch/arm64/include/asm/hwcap.h
> +++ b/arch/arm64/include/asm/hwcap.h
> @@ -30,6 +30,7 @@
> #define COMPAT_HWCAP_IDIVA (1 << 17)
> #define COMPAT_HWCAP_IDIVT (1 << 18)
> #define COMPAT_HWCAP_IDIV (COMPAT_HWCAP_IDIVA|COMPAT_HWCAP_IDIVT)
> +#define COMPAT_HWCAP_EVTSTRM (1 << 21)
Looking at the context, we should also add COMPAT_HWCAP_LPAE as a separate
patch (not part of this series).
> #ifndef __ASSEMBLY__
> /*
> @@ -41,7 +42,8 @@
> COMPAT_HWCAP_FAST_MULT|COMPAT_HWCAP_EDSP|\
> COMPAT_HWCAP_TLS|COMPAT_HWCAP_VFP|\
> COMPAT_HWCAP_VFPv3|COMPAT_HWCAP_VFPv4|\
> - COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV)
> + COMPAT_HWCAP_NEON|COMPAT_HWCAP_IDIV|\
> + COMPAT_HWCAP_EVTSTRM)
So here you're hardcoding COMPAT_HWCAP_EVTSTRM in the COMPAT_ELF_HWCAP, yet
we only enable the native one from the arch-timer driver. The question then is
"Can we rely on the event-stream working for AArch64?". If so, we don't need
the native hwcap at all. If not, then we need to make the compat hwcap
dynamic.
Will
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