BugLink: http://bugs.launchpad.net/bugs/1195483
This reverts commit 657445fe8660100ad174600ebfa61536392b7624.
Signed-off-by: Joseph Salisbury <joseph.salisb...@canonical.com>
Cc: Daniel Vetter <daniel.vet...@ffwll.ch>
Cc: Paulo Zanoni <przan...@gmail.com>
Cc: David Airlie <airl...@linux.ie>
Cc: stable@vger.kernel.org
---
drivers/gpu/drm/i915/intel_dp.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 26e162b..ce933ad 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -709,10 +709,7 @@ intel_dp_compute_config(struct intel_encoder *encoder,
/* Walk through all bpp values. Luckily they're all nicely spaced with 2
* bpc in between. */
- bpp = pipe_config->pipe_bpp;
- if (is_edp(intel_dp) && dev_priv->vbt.edp_bpp)
- bpp = min_t(int, bpp, dev_priv->vbt.edp_bpp);
-
+ bpp = min_t(int, 8*3, pipe_config->pipe_bpp);
for (; bpp >= 6*3; bpp -= 2*3) {
mode_rate = intel_dp_link_required(adjusted_mode->clock, bpp);
@@ -763,6 +760,19 @@ found:
&pipe_config->dp_m_n);
intel_dp_set_clock(encoder, pipe_config, intel_dp->link_bw);
+ /*
+ * XXX: We have a strange regression where using the vbt edp bpp value
+ * for the link bw computation results in black screens, the panel only
+ * works when we do the computation at the usual 24bpp (but still
+ * requires us to use 18bpp). Until that's fully debugged, stay
+ * bug-for-bug compatible with the old code.
+ */
+ if (is_edp(intel_dp) && dev_priv->vbt.edp_bpp) {
+ DRM_DEBUG_KMS("clamping display bpc (was %d) to eDP (%d)\n",
+ bpp, dev_priv->vbt.edp_bpp);
+ bpp = min_t(int, bpp, dev_priv->vbt.edp_bpp);
+ }
+ pipe_config->pipe_bpp = bpp;
return true;
}
--
1.7.9.5
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