From be88a0cdfd1eea61e90a156cf4cb1c6d484da831 Mon Sep 17 00:00:00 2001
From: Mikita Lipski <mikita.lipski@amd.com>
Date: Fri, 20 Sep 2019 15:44:56 -0400
Subject: drm/dp_mst: Add new quirk for Synaptics MST hubs
Git-commit: 5b03f9d86880711441c5681244d352212460a595
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
Synaptics DP1.4 hubs (BRANCH_ID 0x90CC24) do not
support virtual DPCD registers, but do support DSC.
The DSC caps can be read from the physical aux,
like in SST DSC. These hubs have many different
DEVICE_IDs. Add a new quirk to detect this case.
v2: Fix error when checking return of drm_dp_read_desc
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: David Francis <David.Francis@amd.com>
Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/drm_dp_helper.c | 2 ++
drivers/gpu/drm/drm_dp_mst_topology.c | 27 +++++++++++++++++++++++++++
include/drm/drm_dp_helper.h | 7 +++++++
3 files changed, 36 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 2faef8bd911f..374cedc6c2ac 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -1165,6 +1165,8 @@ static const struct dpcd_quirk dpcd_quirk_list[] = {
{ OUI(0x00, 0x10, 0xfa), DEVICE_ID_ANY, false, BIT(DP_DPCD_QUIRK_NO_PSR) },
/* CH7511 seems to leave SINK_COUNT zeroed */
{ OUI(0x00, 0x00, 0x00), DEVICE_ID('C', 'H', '7', '5', '1', '1'), false, BIT(DP_DPCD_QUIRK_NO_SINK_COUNT) },
+ /* Synaptics DP1.4 MST hubs can support DSC without virtual DPCD */
+ { OUI(0x90, 0xCC, 0x24), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) },
};
#undef OUI
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 72cdfeb12b0c..4f92c4cf0469 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -5201,6 +5201,7 @@ struct drm_dp_aux *drm_dp_mst_dsc_aux_for_port(struct drm_dp_mst_port *port)
{
struct drm_dp_mst_port *immediate_upstream_port;
struct drm_dp_mst_port *fec_port;
+ struct drm_dp_desc desc = { 0 };
u8 endpoint_fec;
u8 endpoint_dsc;
@@ -5253,6 +5254,32 @@ struct drm_dp_aux *drm_dp_mst_dsc_aux_for_port(struct drm_dp_mst_port *port)
if (drm_dp_mst_is_virtual_dpcd(port))
return &port->aux;
+ /*
+ * Synaptics quirk
+ * Applies to ports for which:
+ * - Physical aux has Synaptics OUI
+ * - DPv1.4 or higher
+ * - Port is on primary branch device
+ * - Not a VGA adapter (DP_DWN_STRM_PORT_TYPE_ANALOG)
+ */
+ if (drm_dp_read_desc(port->mgr->aux, &desc, true))
+ return NULL;
+
+ if (drm_dp_has_quirk(&desc, DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) &&
+ port->mgr->dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14 &&
+ port->parent == port->mgr->mst_primary) {
+ u8 downstreamport;
+
+ if (drm_dp_dpcd_read(&port->aux, DP_DOWNSTREAMPORT_PRESENT,
+ &downstreamport, 1) < 0)
+ return NULL;
+
+ if ((downstreamport & DP_DWN_STRM_PORT_PRESENT) &&
+ ((downstreamport & DP_DWN_STRM_PORT_TYPE_MASK)
+ != DP_DWN_STRM_PORT_TYPE_ANALOG))
+ return port->mgr->aux;
+ }
+
/*
* The check below verifies if the MST sink
* connected to the GPU is capable of DSC -
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 8f8f3632e697..0aeaf4a8951c 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1522,6 +1522,13 @@ enum drm_dp_quirk {
* The driver should ignore SINK_COUNT during detection.
*/
DP_DPCD_QUIRK_NO_SINK_COUNT,
+ /**
+ * @DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD:
+ *
+ * The device supports MST DSC despite not supporting Virtual DPCD.
+ * The DSC caps can be read from the physical aux instead.
+ */
+ DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD,
};
/**
--
2.28.0