From 18354b422ce4ce1124277dfe8f4f094bae0102ad Mon Sep 17 00:00:00 2001 From: Ville Syrjälä Date: Tue, 23 Oct 2018 21:21:02 +0300 Subject: drm/i915: Don't apply the 16Gb DIMM wm latency w/a to BXT/GLK MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The 16Gb DIMM w/a is not applicable to BXT or GLK. Limit it to the appropriate platforms. This was especially harsh on GLK since we don't even try to read the DIMM information on that platforms, hence valid_dimm was always false and thus we always tried to apply the w/a. Furthermore the w/a pushed the level 0 latency above the level 1 latency, which doesn't really make sense. v2: Do the check when populating is_16gb_dimm (Mahesh) Cc: Mahesh Kumar Cc: Maarten Lankhorst Fixes: 86b592876cb6 ("drm/i915: Implement 16GB dimm wa for latency level-0") Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20181023182102.31549-1-ville.syrjala@linux.intel.com Reviewed-by: Rodrigo Vivi Reviewed-by: Mahesh Kumar (cherry picked from commit 5d6f36b27d2764f3dc940606ee6b7ec5c669af3e) Signed-off-by: Joonas Lahtinen --- drivers/gpu/drm/i915/intel_pm.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'drivers/gpu/drm/i915/intel_pm.c') diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 1db9b8328275..245f0022bcfd 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -2881,8 +2881,7 @@ static void intel_read_wm_latency(struct drm_i915_private *dev_priv, * any underrun. If not able to get Dimm info assume 16GB dimm * to avoid any underrun. */ - if (!dev_priv->dram_info.valid_dimm || - dev_priv->dram_info.is_16gb_dimm) + if (dev_priv->dram_info.is_16gb_dimm) wm[0] += 1; } else if (IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv)) { -- cgit From 21556350ade3cb5d7afecc8b3544e56431d21695 Mon Sep 17 00:00:00 2001 From: Ville Syrjälä Date: Wed, 14 Nov 2018 19:34:40 +0200 Subject: drm/i915: Disable LP3 watermarks on all SNB machines MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit I have a Thinkpad X220 Tablet in my hands that is losing vblank interrupts whenever LP3 watermarks are used. If I nudge the latency value written to the WM3 register just by one in either direction the problem disappears. That to me suggests that the punit will not enter the corrsponding powersave mode (MPLL shutdown IIRC) unless the latency value in the register matches exactly what we read from SSKPD. Ie. it's not really a latency value but rather just a cookie by which the punit can identify the desired power saving state. On HSW/BDW this was changed such that we actually just write the WM level number into those bits, which makes much more sense given the observed behaviour. We could try to handle this by disallowing LP3 watermarks only when vblank interrupts are enabled but we'd first have to prove that only vblank interrupts are affected, which seems unlikely. Also we can't grab the wm mutex from the vblank enable/disable hooks because those are called with various spinlocks held. Thus we'd have to redesigne the watermark locking. So to play it safe and keep the code simple we simply disable LP3 watermarks on all SNB machines. To do that we simply zero out the latency values for watermark level 3, and we adjust the watermark computation to check for that. The behaviour now matches that of the g4x/vlv/skl wm code in the presence of a zeroed latency value. v2: s/USHRT_MAX/U32_MAX/ for consistency with the types (Chris) Cc: stable@vger.kernel.org Cc: Chris Wilson Acked-by: Chris Wilson Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101269 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103713 Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20181114173440.6730-1-ville.syrjala@linux.intel.com (cherry picked from commit 03981c6ebec4fc7056b9b45f847393aeac90d060) Signed-off-by: Joonas Lahtinen --- drivers/gpu/drm/i915/intel_pm.c | 41 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-) (limited to 'drivers/gpu/drm/i915/intel_pm.c') diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 245f0022bcfd..3fe358db1276 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -2493,6 +2493,9 @@ static uint32_t ilk_compute_pri_wm(const struct intel_crtc_state *cstate, uint32_t method1, method2; int cpp; + if (mem_value == 0) + return U32_MAX; + if (!intel_wm_plane_visible(cstate, pstate)) return 0; @@ -2522,6 +2525,9 @@ static uint32_t ilk_compute_spr_wm(const struct intel_crtc_state *cstate, uint32_t method1, method2; int cpp; + if (mem_value == 0) + return U32_MAX; + if (!intel_wm_plane_visible(cstate, pstate)) return 0; @@ -2545,6 +2551,9 @@ static uint32_t ilk_compute_cur_wm(const struct intel_crtc_state *cstate, { int cpp; + if (mem_value == 0) + return U32_MAX; + if (!intel_wm_plane_visible(cstate, pstate)) return 0; @@ -3008,6 +3017,34 @@ static void snb_wm_latency_quirk(struct drm_i915_private *dev_priv) intel_print_wm_latency(dev_priv, "Cursor", dev_priv->wm.cur_latency); } +static void snb_wm_lp3_irq_quirk(struct drm_i915_private *dev_priv) +{ + /* + * On some SNB machines (Thinkpad X220 Tablet at least) + * LP3 usage can cause vblank interrupts to be lost. + * The DEIIR bit will go high but it looks like the CPU + * never gets interrupted. + * + * It's not clear whether other interrupt source could + * be affected or if this is somehow limited to vblank + * interrupts only. To play it safe we disable LP3 + * watermarks entirely. + */ + if (dev_priv->wm.pri_latency[3] == 0 && + dev_priv->wm.spr_latency[3] == 0 && + dev_priv->wm.cur_latency[3] == 0) + return; + + dev_priv->wm.pri_latency[3] = 0; + dev_priv->wm.spr_latency[3] = 0; + dev_priv->wm.cur_latency[3] = 0; + + DRM_DEBUG_KMS("LP3 watermarks disabled due to potential for lost interrupts\n"); + intel_print_wm_latency(dev_priv, "Primary", dev_priv->wm.pri_latency); + intel_print_wm_latency(dev_priv, "Sprite", dev_priv->wm.spr_latency); + intel_print_wm_latency(dev_priv, "Cursor", dev_priv->wm.cur_latency); +} + static void ilk_setup_wm_latency(struct drm_i915_private *dev_priv) { intel_read_wm_latency(dev_priv, dev_priv->wm.pri_latency); @@ -3024,8 +3061,10 @@ static void ilk_setup_wm_latency(struct drm_i915_private *dev_priv) intel_print_wm_latency(dev_priv, "Sprite", dev_priv->wm.spr_latency); intel_print_wm_latency(dev_priv, "Cursor", dev_priv->wm.cur_latency); - if (IS_GEN6(dev_priv)) + if (IS_GEN6(dev_priv)) { snb_wm_latency_quirk(dev_priv); + snb_wm_lp3_irq_quirk(dev_priv); + } } static void skl_setup_wm_latency(struct drm_i915_private *dev_priv) -- cgit