From 53ca2edcf033f3368b2dc0ef3cbcc2f47d556d13 Mon Sep 17 00:00:00 2001 From: "Lee, Shawn C" Date: Tue, 11 Sep 2018 23:22:50 -0700 Subject: drm: Change limited M/N quirk to constant N quirk. Some DP dongles in particular seem to be fussy about too large link M/N values. Set specific value for N divider can resolve this issue per dongle vendor's comment. So configure N as constant value (0x8000) to instead of reduce M/N formula when specific DP dongle connected. v2: add more comments for issue description and fix typo. v3: add lost commit messages back for version 2 v4: send patch to both intel-gfx and dri-devel Cc: Jani Nikula Cc: Cooper Chiou Cc: Matt Atwood Cc: Maarten Lankhorst Cc: Dhinakaran Pandiyan Cc: Clint Taylor Tested-by: Clint Taylor Signed-off-by: Lee, Shawn C Signed-off-by: Jani Nikula Link: https://patchwork.freedesktop.org/patch/msgid/1536733371-25004-3-git-send-email-shawn.c.lee@intel.com --- drivers/gpu/drm/i915/intel_dp_mst.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'drivers/gpu/drm/i915/intel_dp_mst.c') diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c index 7e3e01607643..b7505879b1f7 100644 --- a/drivers/gpu/drm/i915/intel_dp_mst.c +++ b/drivers/gpu/drm/i915/intel_dp_mst.c @@ -45,8 +45,8 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder, int lane_count, slots; const struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode; int mst_pbn; - bool reduce_m_n = drm_dp_has_quirk(&intel_dp->desc, - DP_DPCD_QUIRK_LIMITED_M_N); + bool constant_n = drm_dp_has_quirk(&intel_dp->desc, + DP_DPCD_QUIRK_CONSTANT_N); if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN) return false; @@ -87,7 +87,7 @@ static bool intel_dp_mst_compute_config(struct intel_encoder *encoder, adjusted_mode->crtc_clock, pipe_config->port_clock, &pipe_config->dp_m_n, - reduce_m_n); + constant_n); pipe_config->dp_m_n.tu = slots; -- cgit v1.2.3