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superm1alexdeucher
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drm/amd/display: Bump the HDMI clock to 340MHz
[Why] DP-HDMI dongles can execeed bandwidth requirements on high resolution monitors. This can lead to pruning the high resolution modes. HDMI 1.3 bumped the clock to 340MHz, but display code never matched it. [How] Set default to (DVI) 165MHz. Once HDMI display is identified update to 340MHz. Reported-by: Dianne Skoll <dianne@skoll.ca> Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4780 Reviewed-by: Chris Park <chris.park@amd.com> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com> Signed-off-by: Matthew Stewart <matthew.stewart2@amd.com> Tested-by: Dan Wheeler <daniel.wheeler@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> (cherry picked from commit ac1e65d) Cc: stable@vger.kernel.org
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2 files changed

Lines changed: 4 additions & 2 deletions

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drivers/gpu/drm/amd/display/dc/dc_hdmi_types.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -41,7 +41,7 @@
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/* kHZ*/
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#define DP_ADAPTOR_DVI_MAX_TMDS_CLK 165000
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/* kHZ*/
44-
#define DP_ADAPTOR_HDMI_SAFE_MAX_TMDS_CLK 165000
44+
#define DP_ADAPTOR_HDMI_SAFE_MAX_TMDS_CLK 340000
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struct dp_hdmi_dongle_signature_data {
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int8_t id[15];/* "DP-HDMI ADAPTOR"*/

drivers/gpu/drm/amd/display/dc/link/link_detection.c

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -336,7 +336,7 @@ static void query_dp_dual_mode_adaptor(
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/* Assume we have no valid DP passive dongle connected */
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*dongle = DISPLAY_DONGLE_NONE;
339-
sink_cap->max_hdmi_pixel_clock = DP_ADAPTOR_HDMI_SAFE_MAX_TMDS_CLK;
339+
sink_cap->max_hdmi_pixel_clock = DP_ADAPTOR_DVI_MAX_TMDS_CLK;
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/* Read DP-HDMI dongle I2c (no response interpreted as DP-DVI dongle)*/
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if (!i2c_read(
@@ -392,6 +392,8 @@ static void query_dp_dual_mode_adaptor(
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}
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}
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if (is_valid_hdmi_signature)
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sink_cap->max_hdmi_pixel_clock = DP_ADAPTOR_HDMI_SAFE_MAX_TMDS_CLK;
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if (is_type2_dongle) {
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uint32_t max_tmds_clk =

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