From 8d2f24ca1f19e1e5ca6b941a3f6488f9ccae5390 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Fri, 1 Nov 2013 10:50:22 +0100 Subject: [PATCH] drm/i915: scramble reset support for DP port CRC on vlv They've moved the DC balance reset bit around. Again I don't think we need it, but better safe than sorry and maybe HDMI port CRC will prove useful for checking infoframes or hdmi audio. v2: Apply the suggestions from Damien's review. Reviewed-by: Damien Lespiau Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_debugfs.c | 46 +++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index 881251611512..82c58eb1aa66 100644 --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -2026,6 +2026,9 @@ static int vlv_pipe_crc_ctl_reg(struct drm_device *dev, enum intel_pipe_crc_source *source, uint32_t *val) { + struct drm_i915_private *dev_priv = dev->dev_private; + bool need_stable_symbols = false; + if (*source == INTEL_PIPE_CRC_SOURCE_AUTO) { int ret = i9xx_pipe_crc_auto_source(dev, pipe, source); if (ret) @@ -2038,9 +2041,11 @@ static int vlv_pipe_crc_ctl_reg(struct drm_device *dev, break; case INTEL_PIPE_CRC_SOURCE_DP_B: *val = PIPE_CRC_ENABLE | PIPE_CRC_SOURCE_DP_B_VLV; + need_stable_symbols = true; break; case INTEL_PIPE_CRC_SOURCE_DP_C: *val = PIPE_CRC_ENABLE | PIPE_CRC_SOURCE_DP_C_VLV; + need_stable_symbols = true; break; case INTEL_PIPE_CRC_SOURCE_NONE: *val = 0; @@ -2049,6 +2054,29 @@ static int vlv_pipe_crc_ctl_reg(struct drm_device *dev, return -EINVAL; } + /* + * When the pipe CRC tap point is after the transcoders we need + * to tweak symbol-level features to produce a deterministic series of + * symbols for a given frame. We need to reset those features only once + * a frame (instead of every nth symbol): + * - DC-balance: used to ensure a better clock recovery from the data + * link (SDVO) + * - DisplayPort scrambling: used for EMI reduction + */ + if (need_stable_symbols) { + uint32_t tmp = I915_READ(PORT_DFT2_G4X); + + WARN_ON(!IS_G4X(dev)); + + tmp |= DC_BALANCE_RESET_VLV; + if (pipe == PIPE_A) + tmp |= PIPE_A_SCRAMBLE_RESET; + else + tmp |= PIPE_B_SCRAMBLE_RESET; + + I915_WRITE(PORT_DFT2_G4X, tmp); + } + return 0; } @@ -2128,6 +2156,22 @@ static int i9xx_pipe_crc_ctl_reg(struct drm_device *dev, return 0; } +static void vlv_undo_pipe_scramble_reset(struct drm_device *dev, + enum pipe pipe) +{ + struct drm_i915_private *dev_priv = dev->dev_private; + uint32_t tmp = I915_READ(PORT_DFT2_G4X); + + if (pipe == PIPE_A) + tmp &= ~PIPE_A_SCRAMBLE_RESET; + else + tmp &= ~PIPE_B_SCRAMBLE_RESET; + if (!(tmp & PIPE_SCRAMBLE_RESET_MASK)) + tmp &= ~DC_BALANCE_RESET_VLV; + I915_WRITE(PORT_DFT2_G4X, tmp); + +} + static void g4x_undo_pipe_scramble_reset(struct drm_device *dev, enum pipe pipe) { @@ -2267,6 +2311,8 @@ static int pipe_crc_set_source(struct drm_device *dev, enum pipe pipe, if (IS_G4X(dev)) g4x_undo_pipe_scramble_reset(dev, pipe); + else if (IS_VALLEYVIEW(dev)) + vlv_undo_pipe_scramble_reset(dev, pipe); } return 0; -- 2.30.2