IVB shares 4 lanes between FDI B and FDI C. When sharing, compute the
maximum BPC based on the available bandwidth.
Signed-off-by: Keith Packard <keithp at keithp.com>
---
drivers/gpu/drm/i915/intel_display.c | 101 +++++++++++++++++++++++++++++++---
1 file changed, 94 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_display.c
b/drivers/gpu/drm/i915/intel_display.c
index 70d30fc..7106807 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3575,7 +3575,7 @@ void intel_encoder_destroy(struct drm_encoder *encoder)
}
static bool intel_crtc_mode_fixup(struct drm_crtc *crtc,
- struct drm_display_mode *mode,
+ const struct drm_display_mode *mode,
struct drm_display_mode *adjusted_mode)
{
struct drm_device *dev = crtc->dev;
@@ -3728,7 +3728,8 @@ static inline bool intel_panel_use_ssc(struct
drm_i915_private *dev_priv)
*/
static bool intel_choose_pipe_bpp_dither(struct drm_crtc *crtc,
unsigned int *pipe_bpp,
- struct drm_display_mode *mode)
+ struct drm_display_mode *mode,
+ int max_fdi_bpp)
{
struct drm_device *dev = crtc->dev;
struct drm_i915_private *dev_priv = dev->dev_private;
@@ -3800,6 +3801,15 @@ static bool intel_choose_pipe_bpp_dither(struct drm_crtc
*crtc,
display_bpc = 6;
}
+ if (display_bpc * 3 > max_fdi_bpp) {
+ if (max_fdi_bpp < 24)
+ display_bpc = 6;
+ else if (max_fdi_bpp < 30)
+ display_bpc = 8;
+ else if (max_fdi_bpp < 36)
+ display_bpc = 10;
+ DRM_DEBUG_KMS("Dithering FDI to %dbpc\n", display_bpc);
+ }
/*
* We could just drive the pipe at the highest bpc all the time and
* enable dithering as needed, but that costs bandwidth. So choose
@@ -4570,6 +4580,53 @@ static int ironlake_get_refclk(struct drm_crtc *crtc)
return 120000;
}
+/*
+ * FDI C can only have 2 lanes, borrowed from FDI B
+ */
+
+static int ivb_fdi_max_lanes(struct drm_crtc *crtc)
+{
+ struct drm_device *dev = crtc->dev;
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+ enum pipe other_pipe;
+ struct drm_crtc *other_crtc;
+ struct intel_crtc *other_intel_crtc;
+ int max_lanes;
+
+ /* FDI links B and C share 4 lanes */
+ switch (intel_crtc->pipe) {
+ case PIPE_B:
+ other_pipe = PIPE_C;
+ max_lanes = 4;
+ break;
+ case PIPE_C:
+ other_pipe = PIPE_B;
+ max_lanes = 2;
+ break;
+ default:
+ return 4;
+ }
+ other_crtc = dev_priv->pipe_to_crtc_mapping[other_pipe];
+ other_intel_crtc = to_intel_crtc(other_crtc);
+
+ /* If the other FDI link isn't running, we can use all of the
+ * available lanes
+ */
+ if (!other_intel_crtc->active)
+ return max_lanes;
+
+ /* If the other FDI link is using too many lanes, we can't have
+ * any
+ */
+ if (other_intel_crtc->fdi_lanes > 2)
+ return 0;
+
+ /* When both are running, we only get 2 lanes at most
+ */
+ return 2;
+}
+
static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
struct drm_display_mode *mode,
struct drm_display_mode *adjusted_mode,
@@ -4595,6 +4652,8 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
unsigned int pipe_bpp;
bool dither;
bool is_cpu_edp = false, is_pch_edp = false;
+ int max_fdi_bpp;
+ int max_lane;
for_each_encoder_on_crtc(dev, crtc, encoder) {
switch (encoder->type) {
@@ -4672,7 +4731,18 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
according to current link config */
if (is_cpu_edp) {
intel_edp_link_config(edp_encoder, &lane, &link_bw);
+ max_fdi_bpp = 0;
+ max_lane = lane;
} else {
+ u32 fdi_bw;
+
+ /* [e]DP over FDI requires target mode clock
+ instead of link clock */
+ if (is_dp)
+ target_clock = mode->clock;
+ else
+ target_clock = adjusted_mode->clock;
+
/* FDI is a binary signal running at ~2.7GHz, encoding
* each output octet as 10 bits. The actual frequency
* is stored as a divider into a 100MHz clock, and the
@@ -4681,6 +4751,18 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
* is:
*/
link_bw = intel_fdi_link_freq(dev) * MHz(100)/KHz(1)/10;
+
+ max_lane = 4;
+ if (IS_IVYBRIDGE(dev))
+ max_lane = ivb_fdi_max_lanes(crtc);
+
+ /*
+ * Compute the available FDI bandwidth, use that
+ * to compute the maximum supported BPP
+ */
+ fdi_bw = link_bw * max_lane * 19 / 20;
+ max_fdi_bpp = fdi_bw / target_clock;
+ DRM_DEBUG_KMS("max lane %d yields max fdi bpp %d\n", max_lane,
max_fdi_bpp);
}
/* [e]DP over FDI requires target mode clock instead of link clock. */
@@ -4694,7 +4776,7 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
/* determine panel color depth */
temp = I915_READ(PIPECONF(pipe));
temp &= ~PIPE_BPC_MASK;
- dither = intel_choose_pipe_bpp_dither(crtc, &pipe_bpp, mode);
+ dither = intel_choose_pipe_bpp_dither(crtc, &pipe_bpp, mode,
max_fdi_bpp);
switch (pipe_bpp) {
case 18:
temp |= PIPE_6BPC;
@@ -4716,19 +4798,24 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
break;
}
- intel_crtc->bpp = pipe_bpp;
- I915_WRITE(PIPECONF(pipe), temp);
-
if (!lane) {
/*
* Account for spread spectrum to avoid
* oversubscribing the link. Max center spread
* is 2.5%; use 5% for safety's sake.
*/
- u32 bps = target_clock * intel_crtc->bpp * 21 / 20;
+ u32 bps = target_clock * pipe_bpp * 21 / 20;
lane = bps / (link_bw * 8) + 1;
+ if (lane > max_lane) {
+ DRM_ERROR("Not enough lanes available for mode! (want
%d have %d)\n",
+ lane, max_lane);
+ return -EINVAL;
+ }
}
+ intel_crtc->bpp = pipe_bpp;
+ I915_WRITE(PIPECONF(pipe), temp);
+
intel_crtc->fdi_lanes = lane;
if (pixel_multiplier > 1)
--
1.7.10.4
