[Bug 107113] APL: Fails to detect second external monitor after a 4k monitor is attached to DUT

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=107113

--- Comment #4 from Shawn Lee <shawn.c.lee at intel.com> ---
We did following change and got positive result for this symptom.

1. Do not apply additional latency for watermark setup on BXT/APL platform.
2. Modify min_scanlines to 4 in skl_ddb_min_alloc().

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 2cc12b48b74d..41357b80a603 100644
— a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2935,7 +2935,7 @@ static bool skl_needs_memory_bw_wa(struct
intel_atomic_state *state)
{
struct drm_i915_private *dev_priv = to_i915(state->base.dev);

- if (IS_SKYLAKE(dev_priv) || IS_BROXTON(dev_priv) ||
+ if (IS_SKYLAKE(dev_priv) ||
IS_KABYLAKE(dev_priv))
return true;
@@ -3476,7 +3476,7 @@ skl_ddb_min_alloc(const struct drm_plane_state *pstate,
const int plane)
struct drm_framebuffer *fb = pstate->fb;
struct intel_plane_state *intel_pstate = to_intel_plane_state(pstate);
uint32_t src_w, src_h;

- uint32_t min_scanlines = 8;
+ uint32_t min_scanlines = 4;
uint8_t plane_bpp;

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