From 8409360381ebaaab82c7ab502665a29423fcdfc2 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Fri, 1 Nov 2013 10:50:21 +0100 Subject: [PATCH] drm/i915: scramble reset support for DP port CRC on g4x We need to reset the DP scrambler on every vsync to get stable CRCs. And since we can't use the normal pipe CRC on DP ports on g4x we really need them to be able to test modesetting issues on (e)DP outputs. Note that the DC balance reset is for SDVO port CRCs so we don't strictly need it. But better safe than sorry (and it's a nice template in case we ever want to grab port CRCs for e.g. audio checking). v2: Apply the suggestions from Damien's review. Reviewed-by: Damien Lespiau Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_debugfs.c | 52 +++++++++++++++++++++++++++++ drivers/gpu/drm/i915/i915_reg.h | 8 +++++ 2 files changed, 60 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index 7c29a8827177..881251611512 100644 --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -2057,6 +2057,9 @@ static int i9xx_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) @@ -2076,16 +2079,19 @@ static int i9xx_pipe_crc_ctl_reg(struct drm_device *dev, if (!IS_G4X(dev)) return -EINVAL; *val = PIPE_CRC_ENABLE | PIPE_CRC_SOURCE_DP_B_G4X; + need_stable_symbols = true; break; case INTEL_PIPE_CRC_SOURCE_DP_C: if (!IS_G4X(dev)) return -EINVAL; *val = PIPE_CRC_ENABLE | PIPE_CRC_SOURCE_DP_C_G4X; + need_stable_symbols = true; break; case INTEL_PIPE_CRC_SOURCE_DP_D: if (!IS_G4X(dev)) return -EINVAL; *val = PIPE_CRC_ENABLE | PIPE_CRC_SOURCE_DP_D_G4X; + need_stable_symbols = true; break; case INTEL_PIPE_CRC_SOURCE_NONE: *val = 0; @@ -2094,9 +2100,52 @@ static int i9xx_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)); + + I915_WRITE(PORT_DFT_I9XX, + I915_READ(PORT_DFT_I9XX) | DC_BALANCE_RESET); + + if (pipe == PIPE_A) + tmp |= PIPE_A_SCRAMBLE_RESET; + else + tmp |= PIPE_B_SCRAMBLE_RESET; + + I915_WRITE(PORT_DFT2_G4X, tmp); + } + return 0; } +static void g4x_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; + I915_WRITE(PORT_DFT2_G4X, tmp); + + if (!(tmp & PIPE_SCRAMBLE_RESET_MASK)) { + I915_WRITE(PORT_DFT_I9XX, + I915_READ(PORT_DFT_I9XX) & ~DC_BALANCE_RESET); + } +} + static int ilk_pipe_crc_ctl_reg(enum intel_pipe_crc_source *source, uint32_t *val) { @@ -2215,6 +2264,9 @@ static int pipe_crc_set_source(struct drm_device *dev, enum pipe pipe, spin_unlock_irq(&pipe_crc->lock); kfree(entries); + + if (IS_G4X(dev)) + g4x_undo_pipe_scramble_reset(dev, pipe); } return 0; diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h index 3dfcac7ef3c4..4328e3bd63b2 100644 --- a/drivers/gpu/drm/i915/i915_reg.h +++ b/drivers/gpu/drm/i915/i915_reg.h @@ -2150,6 +2150,14 @@ #define PCH_HDMIC 0xe1150 #define PCH_HDMID 0xe1160 +#define PORT_DFT_I9XX 0x61150 +#define DC_BALANCE_RESET (1 << 25) +#define PORT_DFT2_G4X 0x61154 +#define DC_BALANCE_RESET_VLV (1 << 31) +#define PIPE_SCRAMBLE_RESET_MASK (0x3 << 0) +#define PIPE_B_SCRAMBLE_RESET (1 << 1) +#define PIPE_A_SCRAMBLE_RESET (1 << 0) + /* Gen 3 SDVO bits: */ #define SDVO_ENABLE (1 << 31) #define SDVO_PIPE_SEL(pipe) ((pipe) << 30) -- GitLab