From 233624e0d5a0854638eff9e77fc37161890e9440 Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Mon, 2 Aug 2021 22:01:48 +0300 Subject: drm/i915: Apply CMTG clock disabling WA while DPLL0 is enabled MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit CI test results/further experiments show that the workaround added in commit 573d7ce4f69a ("drm/i915/adlp: Add workaround to disable CMTG clock gating") can be applied only while DPLL0 is enabled. If it's disabled the TRANS_CMTG_CHICKEN register is not accessible. Accordingly move the WA to DPLL0 HW state sanitization and enabling. This fixes an issue where the WA won't get applied (and a WARN is thrown due to an unexpected value in TRANS_CMTG_CHICKEN) if the driver is loaded without DPLL0 being enabled: booting without BIOS enabling an output with this PLL, or reloading the driver. While at it also add a debug print for the unexpected register value. Cc: José Roberto de Souza Signed-off-by: Imre Deak Reviewed-by: José Roberto de Souza Link: https://patchwork.freedesktop.org/patch/msgid/20210802190148.2099625-1-imre.deak@intel.com --- drivers/gpu/drm/i915/display/intel_dpll_mgr.c | 34 ++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-) (limited to 'drivers/gpu/drm/i915/display/intel_dpll_mgr.c') diff --git a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c index a379649d3e9e..94718c573283 100644 --- a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c +++ b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c @@ -3735,6 +3735,31 @@ static void icl_pll_enable(struct drm_i915_private *dev_priv, drm_err(&dev_priv->drm, "PLL %d not locked\n", pll->info->id); } +static void adlp_cmtg_clock_gating_wa(struct drm_i915_private *i915, struct intel_shared_dpll *pll) +{ + u32 val; + + if (!IS_ADLP_DISPLAY_STEP(i915, STEP_A0, STEP_B0) || + pll->info->id != DPLL_ID_ICL_DPLL0) + return; + /* + * Wa_16011069516:adl-p[a0] + * + * All CMTG regs are unreliable until CMTG clock gating is disabled, + * so we can only assume the default TRANS_CMTG_CHICKEN reg value and + * sanity check this assumption with a double read, which presumably + * returns the correct value even with clock gating on. + * + * Instead of the usual place for workarounds we apply this one here, + * since TRANS_CMTG_CHICKEN is only accessible while DPLL0 is enabled. + */ + val = intel_de_read(i915, TRANS_CMTG_CHICKEN); + val = intel_de_read(i915, TRANS_CMTG_CHICKEN); + intel_de_write(i915, TRANS_CMTG_CHICKEN, DISABLE_DPT_CLK_GATING); + if (drm_WARN_ON(&i915->drm, val & ~DISABLE_DPT_CLK_GATING)) + drm_dbg_kms(&i915->drm, "Unexpected flags in TRANS_CMTG_CHICKEN: %08x\n", val); +} + static void combo_pll_enable(struct drm_i915_private *dev_priv, struct intel_shared_dpll *pll) { @@ -3764,6 +3789,8 @@ static void combo_pll_enable(struct drm_i915_private *dev_priv, icl_pll_enable(dev_priv, pll, enable_reg); + adlp_cmtg_clock_gating_wa(dev_priv, pll); + /* DVFS post sequence would be here. See the comment above. */ } @@ -4273,7 +4300,12 @@ void intel_dpll_readout_hw_state(struct drm_i915_private *i915) static void sanitize_dpll_state(struct drm_i915_private *i915, struct intel_shared_dpll *pll) { - if (!pll->on || pll->active_mask) + if (!pll->on) + return; + + adlp_cmtg_clock_gating_wa(i915, pll); + + if (pll->active_mask) return; drm_dbg_kms(&i915->drm, -- cgit v1.2.3-59-g8ed1b