From 367294be7c257dd4d8d8f0e296aa9824eae18568 Mon Sep 17 00:00:00 2001 From: Vandana Kannan Date: Tue, 4 Nov 2014 17:06:46 +0000 Subject: [PATCH] drm/i915/gen9: Add 2us read latency to WM level MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit According to the updated Bspec, The mailbox response data is not currently accounting for memory read latency. Add 2 microseconds to the result for each level. This patch adds 2us to latency of level 0 for all cases and for all other levels (1-7) only if latency[level] > 0. v2: Slightly rework the patch and add a big comment (Damien) v3: Rebase on top of the renames of the memory latency defines Signed-off-by: Vandana Kannan (v1) Signed-off-by: Damien Lespiau Reviewed-by: Ville Syrjälä (v2) Reviewed-by: M, Satheeshakrishna (v1) Cc: Lespiau, Damien Cc: M, Satheeshakrishna Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_pm.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 09a81b3a754d..44fecfc3fc52 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -2286,6 +2286,7 @@ static void intel_read_wm_latency(struct drm_device *dev, uint16_t wm[8]) if (IS_GEN9(dev)) { uint32_t val; int ret; + int level, max_level = ilk_wm_max_level(dev); /* read the first set of memory latencies[0:3] */ val = 0; /* data0 to be programmed to 0 for first set */ @@ -2328,6 +2329,21 @@ static void intel_read_wm_latency(struct drm_device *dev, uint16_t wm[8]) wm[7] = (val >> GEN9_MEM_LATENCY_LEVEL_3_7_SHIFT) & GEN9_MEM_LATENCY_LEVEL_MASK; + /* + * punit doesn't take into account the read latency so we need + * to add 2us to the various latency levels we retrieve from + * the punit. + * - W0 is a bit special in that it's the only level that + * can't be disabled if we want to have display working, so + * we always add 2us there. + * - For levels >=1, punit returns 0us latency when they are + * disabled, so we respect that and don't add 2us then + */ + wm[0] += 2; + for (level = 1; level <= max_level; level++) + if (wm[level] != 0) + wm[level] += 2; + } else if (IS_HASWELL(dev) || IS_BROADWELL(dev)) { uint64_t sskpd = I915_READ64(MCH_SSKPD);