From 215733fadb87709e91b3a622d786865292c9ab11 Mon Sep 17 00:00:00 2001 From: Paulo Zanoni Date: Mon, 19 Aug 2013 13:18:07 -0300 Subject: [PATCH] drm/i915: grab force_wake when restoring LCPLL If LCPLL is disabled, there's a chance we might be in package C8 state or deeper, and we'll get a hard hang when restoring LCPLL (also, a red led lights up on my motherboard). So grab the force_wake, which will get us out of RC6 and, as a consequence, out of PC8+ (since we need RC6 to get into PC8+). Note: Discussions with hw designers are still ongoing what exactly goes boom here. But I think we can go ahead and just merge this little hack for now until it's clear what we actually need. Signed-off-by: Paulo Zanoni [danvet: Add small note about the current state of the discussion around this hack.] Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_display.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 7a40427823c7..a2c8cb360ae8 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -6033,6 +6033,10 @@ void hsw_restore_lcpll(struct drm_i915_private *dev_priv) LCPLL_POWER_DOWN_ALLOW)) == LCPLL_PLL_LOCK) return; + /* Make sure we're not on PC8 state before disabling PC8, otherwise + * we'll hang the machine! */ + dev_priv->uncore.funcs.force_wake_get(dev_priv); + if (val & LCPLL_POWER_DOWN_ALLOW) { val &= ~LCPLL_POWER_DOWN_ALLOW; I915_WRITE(LCPLL_CTL, val); @@ -6060,6 +6064,8 @@ void hsw_restore_lcpll(struct drm_i915_private *dev_priv) LCPLL_CD_SOURCE_FCLK_DONE) == 0, 1)) DRM_ERROR("Switching back to LCPLL failed\n"); } + + dev_priv->uncore.funcs.force_wake_put(dev_priv); } static void haswell_modeset_global_resources(struct drm_device *dev) -- 2.39.5