From 91e630b9e636954708e933015e7f02f8bcd8b320 Mon Sep 17 00:00:00 2001 From: Tvrtko Ursulin Date: Tue, 4 Oct 2016 09:29:21 +0100 Subject: [PATCH] drm/i915: Use binary search when looking up forcewake domains Instead of the existing linear seach, now that we have sorted range tables, we can do a binary search on them for some potential miniscule performance gain, but more importantly for elegance and code size. Hopefully the perfomance gain is sufficient to offset the function calls which were not there before. v2: Removed const cast away. Signed-off-by: Tvrtko Ursulin Reviewed-by: Chris Wilson --- drivers/gpu/drm/i915/intel_uncore.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c index aa84c40..aa89815 100644 --- a/drivers/gpu/drm/i915/intel_uncore.c +++ b/drivers/gpu/drm/i915/intel_uncore.c @@ -26,6 +26,7 @@ #include "i915_vgpu.h" #include +#include #define FORCEWAKE_ACK_TIMEOUT_MS 50 @@ -589,20 +590,30 @@ struct intel_forcewake_range enum forcewake_domains domains; }; +static int fw_range_cmp(const void *key, const void *elt) +{ + const struct intel_forcewake_range *entry = elt; + u32 offset = (u32)((unsigned long)key); + + if (offset < entry->start) + return -1; + else if (offset > entry->end) + return 1; + else + return 0; +} + static enum forcewake_domains find_fw_domain(u32 offset, const struct intel_forcewake_range *ranges, unsigned int num_ranges) { - unsigned int i; - struct intel_forcewake_range *entry = - (struct intel_forcewake_range *)ranges; + struct intel_forcewake_range *entry; - for (i = 0; i < num_ranges; i++, entry++) { - if (offset >= entry->start && offset <= entry->end) - return entry->domains; - } + entry = bsearch((void *)(unsigned long)offset, (const void *)ranges, + num_ranges, sizeof(struct intel_forcewake_range), + fw_range_cmp); - return -1; + return entry ? entry->domains : -1; } static void -- 2.7.4