From 020c1b5a20fa94338a9fbc156c5b6babd5b2ae4b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Tue, 4 Jun 2019 17:48:57 +0300 Subject: [PATCH] drm/i915: Do not touch the PCH SSC reference if a PLL is using it MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Our PCH refclk init code currently assumes that the PCH SSC reference can only be used for FDI. That is not true and it can be used by SPLL/WRPLL for eDP SSC or clock bending as well. Before we go reconfiguring it let's make sure no PLL is currently using the PCH SSC reference. This will mean that we won't reconfigure the PCH SSC reference properly for FDI in case the BIOS has decided to use it for eg. clock bending. But hopefully that won't happen in practive. We really should move this code to be part of the modeset seqeuence and properly deal with the potentially conflicting requirements imposed on PLL reference clocks. But that requires actual work. Signed-off-by: Ville Syrjälä --- drivers/gpu/drm/i915/i915_reg.h | 1 + drivers/gpu/drm/i915/intel_display.c | 79 ++++++++++++++++++++++++++-- 2 files changed, 77 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h index 07e3f861a92e..d5fee72fc079 100644 --- a/drivers/gpu/drm/i915/i915_reg.h +++ b/drivers/gpu/drm/i915/i915_reg.h @@ -7511,6 +7511,7 @@ enum { #define ILK_eDP_A_DISABLE (1 << 24) #define HSW_CDCLK_LIMIT (1 << 24) #define ILK_DESKTOP (1 << 23) +#define HSW_CPU_SSC_ENABLE (1 << 21) #define ILK_DSPCLK_GATE_D _MMIO(0x42020) #define ILK_VRHUNIT_CLOCK_GATE_DISABLE (1 << 28) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index fc47ed0247c5..75ca2030ffb0 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -9121,22 +9121,95 @@ static void lpt_bend_clkout_dp(struct drm_i915_private *dev_priv, int steps) #undef BEND_IDX +static bool spll_uses_pch_ssc(struct drm_i915_private *dev_priv) +{ + u32 fuse_strap = I915_READ(FUSE_STRAP); + u32 ctl = I915_READ(SPLL_CTL); + + if ((ctl & SPLL_PLL_ENABLE) == 0) + return false; + + if ((ctl & SPLL_PLL_REF_MASK) == SPLL_PLL_SSC && + (fuse_strap & HSW_CPU_SSC_ENABLE) == 0) + return true; + + if (IS_BROADWELL(dev_priv) && + (ctl & SPLL_PLL_REF_MASK) == SPLL_PLL_NON_SSC) + return true; + + return false; +} + +static bool wrpll_uses_pch_ssc(struct drm_i915_private *dev_priv, + enum intel_dpll_id id) +{ + u32 fuse_strap = I915_READ(FUSE_STRAP); + u32 ctl = I915_READ(WRPLL_CTL(id)); + + if ((ctl & WRPLL_PLL_ENABLE) == 0) + return false; + + if ((ctl & WRPLL_PLL_REF_MASK) == WRPLL_PLL_SSC) + return true; + + if ((IS_BROADWELL(dev_priv) || IS_HSW_ULT(dev_priv)) && + (ctl & WRPLL_PLL_REF_MASK) == WRPLL_PLL_NON_SSC && + (fuse_strap & HSW_CPU_SSC_ENABLE) == 0) + return true; + + return false; +} + static void lpt_init_pch_refclk(struct drm_i915_private *dev_priv) { struct intel_encoder *encoder; - bool has_vga = false; + bool pch_ssc_in_use = false; + bool has_fdi = false; for_each_intel_encoder(&dev_priv->drm, encoder) { switch (encoder->type) { case INTEL_OUTPUT_ANALOG: - has_vga = true; + has_fdi = true; break; default: break; } } - if (has_vga) { + /* + * The BIOS may have decided to use the PCH SSC + * reference so we must not disable it until the + * relevant PLLs have stopped relying on it. We'll + * just leave the PCH SSC reference enabled in case + * any active PLL is using it. It will get disabled + * after runtime suspend if we don't have FDI. + * + * TODO: Move the whole reference clock handling + * to the modeset sequence proper so that we can + * actually enable/disable/reconfigure these things + * safely. To do that we need to introduce a real + * clock hierarchy. That would also allow us to do + * clock bending finally. + */ + if (spll_uses_pch_ssc(dev_priv)) { + DRM_DEBUG_KMS("SPLL using PCH SSC\n"); + pch_ssc_in_use = true; + } + + if (wrpll_uses_pch_ssc(dev_priv, DPLL_ID_WRPLL1)) { + DRM_DEBUG_KMS("WRPLL1 using PCH SSC\n"); + pch_ssc_in_use = true; + } + + if (wrpll_uses_pch_ssc(dev_priv, DPLL_ID_WRPLL2)) { + DRM_DEBUG_KMS("WRPLL2 using PCH SSC\n"); + pch_ssc_in_use = true; + } + + if (pch_ssc_in_use) + return; + + if (has_fdi) { lpt_bend_clkout_dp(dev_priv, 0); lpt_enable_clkout_dp(dev_priv, true, true); } else { -- 2.21.0