From: Damien Lespiau <damien.lespiau at intel.com>
The FDI link has supported link reversal to make the PCB layout
engineer's life easier for quite a while and we have always presered
this bit as we programmed FDI_RX_CTL with a read/modify/write sequence.
We're trying to take a bit more control over what the BIOS leaves in
various register and with the introduction of DDI, started to program
FDI_RX_CTL fully.
There's a fused bit to indicate DMI link reversal and FDI defaults to
mirroring that configuration. We have a bit to override that behaviour
that we need to preserve from the BIOS.
Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
---
drivers/gpu/drm/i915/i915_drv.h | 2 +-
drivers/gpu/drm/i915/i915_reg.h | 2 +-
drivers/gpu/drm/i915/intel_crt.c | 14 +++++++++-----
drivers/gpu/drm/i915/intel_ddi.c | 6 ++----
4 files changed, 13 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 557843d..31fc37a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -915,7 +915,7 @@ typedef struct drm_i915_private {
bool hw_contexts_disabled;
uint32_t hw_context_size;
- bool fdi_rx_polarity_reversed;
+ u32 fdi_rx_config;
struct i915_suspend_saved_registers regfile;
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 3f75cfa..ceeac97 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3922,7 +3922,7 @@
#define FDI_10BPC (1<<16)
#define FDI_6BPC (2<<16)
#define FDI_12BPC (3<<16)
-#define FDI_LINK_REVERSE_OVERWRITE (1<<15)
+#define FDI_RX_LINK_REVERSAL_OVERRIDE (1<<15)
#define FDI_DMI_LINK_REVERSE_MASK (1<<14)
#define FDI_RX_PLL_ENABLE (1<<13)
#define FDI_FS_ERR_CORRECT_ENABLE (1<<11)
diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index fe20bf7..86b557e 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -800,10 +800,14 @@ void intel_crt_init(struct drm_device *dev)
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.
+ * TODO: find a proper way to discover whether we need to set the the
+ * polarity and link reversal bits 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);
+ if (HAS_PCH_LPT(dev)) {
+ u32 fdi_config = FDI_RX_POLARITY_REVERSED_LPT |
+ FDI_RX_LINK_REVERSAL_OVERRIDE;
+
+ dev_priv->fdi_rx_config = I915_READ(_FDI_RXA_CTL) & fdi_config;
+ }
}
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 4bad0f7..cb2dcc6 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -178,10 +178,8 @@ void hsw_fdi_link_train(struct drm_crtc *crtc)
FDI_RX_TP1_TO_TP2_48 | FDI_RX_FDI_DELAY_90);
/* 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;
+ rx_ctl_val = dev_priv->fdi_rx_config | FDI_RX_ENHANCE_FRAME_ENABLE |
+ FDI_RX_PLL_ENABLE | ((intel_crtc->fdi_lanes - 1) << 19);
I915_WRITE(_FDI_RXA_CTL, rx_ctl_val);
POSTING_READ(_FDI_RXA_CTL);
udelay(220);
--
1.7.11.7
