linux-kernel - [PATCH 4.19 072/219] drm/amd/display: Fix dongle

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Date:   Sun, 29 Dec 2019 18:17:54 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Galiffi <david.galiffi@....com>,
        Jun Lei <Jun.Lei@....com>,
        Bhawanpreet Lakha <Bhawanpreet.Lakha@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 072/219] drm/amd/display: Fix dongle_caps containing stale information.

From: David Galiffi <david.galiffi@....com>

[ Upstream commit dd998291dbe92106d8c4a7581c409b356928d711 ]

[WHY]

During detection:
function: get_active_converter_info populates link->dpcd_caps.dongle_caps
only when dpcd_rev >= DPCD_REV_11 and DWN_STRM_PORTX_TYPE is
DOWN_STREAM_DETAILED_HDMI or DOWN_STREAM_DETAILED_DP_PLUS_PLUS.
Otherwise, it is not cleared, and stale information remains.

During mode validation:
function: dp_active_dongle_validate_timing reads
link->dpcd_caps.dongle_caps->dongle_type to determine the maximum
pixel clock to support. This information is now stale and no longer
valid.

[HOW]
dp_active_dongle_validate_timing should be using
link->dpcd_caps->dongle_type instead.

Signed-off-by: David Galiffi <david.galiffi@....com>
Reviewed-by: Jun Lei <Jun.Lei@....com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link.c    | 2 +-
 drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index 23a7ef97afdd..c6f7c1344a9b 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -1950,7 +1950,7 @@ static bool dp_active_dongle_validate_timing(
 		break;
 	}
 
-	if (dongle_caps->dongle_type != DISPLAY_DONGLE_DP_HDMI_CONVERTER ||
+	if (dpcd_caps->dongle_type != DISPLAY_DONGLE_DP_HDMI_CONVERTER ||
 		dongle_caps->extendedCapValid == false)
 		return true;
 
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index 05840f5bddd5..122249da03ab 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -2172,6 +2172,7 @@ static void get_active_converter_info(
 	uint8_t data, struct dc_link *link)
 {
 	union dp_downstream_port_present ds_port = { .byte = data };
+	memset(&link->dpcd_caps.dongle_caps, 0, sizeof(link->dpcd_caps.dongle_caps));
 
 	/* decode converter info*/
 	if (!ds_port.fields.PORT_PRESENT) {
-- 
2.20.1