On Fri, Sep 30, 2016 at 06:48:48PM +0100, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
>
> Simply replace the linear search with the kernel's binary
> search implementation. There is only six registers currently
> in that table so this may not be that interesting. It adds a
> function call so hopefully remains performance neutral for now.
>
> v2: No need for manual conversion to bool for return.
> (Joonas Lahtinen)
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_uncore.c | 26 +++++++++++++++++++++-----
> 1 file changed, 21 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index 10b21516a7de..70a7fef79846 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -689,14 +689,30 @@ static void intel_shadow_table_check(void)
> #endif
> }
>
> +static int mmio_reg_cmp(const void *key, const void *elt)
> +{
> + u32 offset = (u32)(unsigned long)key;
> + i915_reg_t *reg = (i915_reg_t *)elt;
> +
> + if (offset < i915_mmio_reg_offset(*reg))
> + return -1;
> + else if (offset > i915_mmio_reg_offset(*reg))
> + return 1;
> + else
> + return 0;
There's no issue with using
return offset - i915_mmio_reg_offset(*reg)
here.
> +}
> +
> static bool is_gen8_shadowed(u32 offset)
> {
> - int i;
> - for (i = 0; i < ARRAY_SIZE(gen8_shadowed_regs); i++)
> - if (offset == gen8_shadowed_regs[i].reg)
> - return true;
> + i915_reg_t *reg;
>
> - return false;
> + reg = bsearch((void *)(unsigned long)offset,
> + (const void *)gen8_shadowed_regs,
> + ARRAY_SIZE(gen8_shadowed_regs),
> + sizeof(i915_reg_t),
> + mmio_reg_cmp);
> +
> + return reg;
Or just return bseearch() ? (Probably like this for easing future
patches.)
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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