linux-kernel - [PATCH 4.19 039/114] drm/nouveau/kms/nv50-: Dont create MSTMs for eDP connectors

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Date:   Thu, 10 Oct 2019 10:35:46 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Lyude Paul <lyude@...hat.com>,
        Ben Skeggs <bskeggs@...hat.com>
Subject: [PATCH 4.19 039/114] drm/nouveau/kms/nv50-: Dont create MSTMs for eDP connectors

From: Lyude Paul <lyude@...hat.com>

commit 698c1aa9f83b618de79e9e5e19a58f70a4a6ae0f upstream.

On the ThinkPad P71, we have one eDP connector exposed along with 5 DP
connectors, resulting in a total of 11 TMDS encoders. Since the GPU on
this system is also capable of MST, we create an additional 4 fake MST
encoders for each DP port. Unfortunately, we also do this for the eDP
port as well, resulting in:

  1 eDP port: +1 TMDS encoder
              +4 DPMST encoders
  5 DP ports: +2 TMDS encoders
              +4 DPMST encoders
	      *5 ports
	      == 35 encoders

Which breaks things, since DRM has a hard coded limit of 32 encoders.
So, fix this by not creating MSTMs for any eDP connectors. This brings
us down to 31 encoders, although we can do better.

This fixes driver probing for nouveau on the ThinkPad P71.

Signed-off-by: Lyude Paul <lyude@...hat.com>
Cc: stable@...r.kernel.org
Signed-off-by: Ben Skeggs <bskeggs@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/nouveau/dispnv50/disp.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -1517,7 +1517,8 @@ nv50_sor_create(struct drm_connector *co
 			nv_encoder->aux = aux;
 		}
 
-		if ((data = nvbios_dp_table(bios, &ver, &hdr, &cnt, &len)) &&
+		if (nv_connector->type != DCB_CONNECTOR_eDP &&
+		    (data = nvbios_dp_table(bios, &ver, &hdr, &cnt, &len)) &&
 		    ver >= 0x40 && (nvbios_rd08(bios, data + 0x08) & 0x04)) {
 			ret = nv50_mstm_new(nv_encoder, &nv_connector->aux, 16,
 					    nv_connector->base.base.id,