[PATCH 1/3] drm/i915/dp: Fail DP MST config when there are not enough vcpi slots

From: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
To: intel-gfx@lists.freedesktop.org
Cc: daniel.vetter@ffwll.ch, dri-devel@lists.freedesktop.org,
	Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Subject: [PATCH 1/3] drm/i915/dp: Fail DP MST config when there are not enough vcpi slots
Date: Thu, 17 Nov 2016 18:03:46 -0800	[thread overview]
Message-ID: <1479434628-2373-2-git-send-email-dhinakaran.pandiyan@intel.com> (raw)
In-Reply-To: <1479434628-2373-1-git-send-email-dhinakaran.pandiyan@intel.com>

drm_dp_find_vcpi_slots() returns an error when there is not enough
available bandwidth on a link to support a mode. This error should make
compute_config() to fail. Not returning false could end up in a modeset
which will not work.

Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
---
 drivers/gpu/drm/i915/intel_dp_mst.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
index e21cf08..4280a83 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -63,6 +63,10 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder,
 
 	pipe_config->pbn = mst_pbn;
 	slots = drm_dp_find_vcpi_slots(&intel_dp->mst_mgr, mst_pbn);
+	if (slots < 0) {
+		DRM_ERROR("not enough available time slots for pbn=%d", mst_pbn);
+		return false;
+	}
 
 	intel_link_compute_m_n(bpp, lane_count,
 			       adjusted_mode->crtc_clock,
-- 
2.7.4

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