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drm/i915: set the LPT FDI RX polarity reversal bit when needed

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If we fail to set the bit when needed we get some nice FDI link
training failures (AKA "black screen on VGA output").

While we don't really know how to properly choose whether we need to
set the bit or not (VBT?), just read the initial value set by the BIOS
and store it for later usage.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Paulo Zanoni 2012-12-01 12:04:26 -02:00 committed by Daniel Vetter
parent dde86e2db5
commit 68d18ad7fb
4 changed files with 13 additions and 0 deletions
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2
drivers/gpu/drm/i915/i915_drv.h
View File

@ -915,6 +915,8 @@ typedef struct drm_i915_private {
bool hw_contexts_disabled;
uint32_t hw_context_size;
bool fdi_rx_polarity_reversed;
struct i915_suspend_saved_registers regfile;
/* Old dri1 support infrastructure, beware the dragons ya fools entering

1
drivers/gpu/drm/i915/i915_reg.h
View File

@ -3917,6 +3917,7 @@
#define FDI_FS_ERRC_ENABLE (1<<27)
#define FDI_FE_ERRC_ENABLE (1<<26)
#define FDI_DP_PORT_WIDTH_X8 (7<<19)
#define FDI_RX_POLARITY_REVERSED_LPT (1<<16)
#define FDI_8BPC (0<<16)
#define FDI_10BPC (1<<16)
#define FDI_6BPC (2<<16)

8
drivers/gpu/drm/i915/intel_crt.c
View File

@ -798,4 +798,12 @@ void intel_crt_init(struct drm_device *dev)
crt->force_hotplug_required = 0;
dev_priv->hotplug_supported_mask |= CRT_HOTPLUG_INT_STATUS;
/*
* TODO: find a proper way to discover whether we need to set the
* polarity reversal bit or not, instead of relying on the BIOS.
*/
if (HAS_PCH_LPT(dev))
dev_priv->fdi_rx_polarity_reversed =
!!(I915_READ(_FDI_RXA_CTL) & FDI_RX_POLARITY_REVERSED_LPT);
}

2
drivers/gpu/drm/i915/intel_ddi.c
View File

@ -180,6 +180,8 @@ void hsw_fdi_link_train(struct drm_crtc *crtc)
/* Enable the PCH Receiver FDI PLL */
rx_ctl_val = FDI_RX_PLL_ENABLE | FDI_RX_ENHANCE_FRAME_ENABLE |
((intel_crtc->fdi_lanes - 1) << 19);
if (dev_priv->fdi_rx_polarity_reversed)
rx_ctl_val |= FDI_RX_POLARITY_REVERSED_LPT;
I915_WRITE(_FDI_RXA_CTL, rx_ctl_val);
POSTING_READ(_FDI_RXA_CTL);
udelay(220);