From: Jimmy Kizito <[email protected]> [Why] LTTPR capable devices on the DisplayPort path may assume that extended LTTPR AUX timeouts will be used after LTTPR capabilities are read.
When DPTX operates in non-LTTPR mode, AUX timeouts are not extended and this can result in AUX transactions timing out. [How] Use shared helper function to determine LTTPR mode and do not read LTTPR capabilities in non-LTTPR mode. Reviewed-by: Mustapha Ghaddar <[email protected]> Reviewed-by: Meenakshikumar Somasundaram <[email protected]> Reviewed-by: Jun Lei <[email protected]> Acked-by: Hamza Mahfooz <[email protected]> Signed-off-by: Jimmy Kizito <[email protected]> --- .../gpu/drm/amd/display/dc/core/dc_link_dp.c | 44 +++++++++++++------ 1 file changed, 31 insertions(+), 13 deletions(-) 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 9b20f340c21f..b5b16340fd39 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 @@ -5134,16 +5134,13 @@ static bool dpcd_read_sink_ext_caps(struct dc_link *link) return true; } -bool dp_retrieve_lttpr_cap(struct dc_link *link) +/* Logic to determine LTTPR mode */ +static void determine_lttpr_mode(struct dc_link *link) { - uint8_t lttpr_dpcd_data[8]; bool allow_lttpr_non_transparent_mode = 0; bool vbios_lttpr_enable = link->dc->caps.vbios_lttpr_enable; bool vbios_lttpr_interop = link->dc->caps.vbios_lttpr_aware; - enum dc_status status = DC_ERROR_UNEXPECTED; - bool is_lttpr_present = false; - memset(lttpr_dpcd_data, '\0', sizeof(lttpr_dpcd_data)); if ((link->dc->config.allow_lttpr_non_transparent_mode.bits.DP2_0 && link->dpcd_caps.channel_coding_cap.bits.DP_128b_132b_SUPPORTED)) { @@ -5153,9 +5150,6 @@ bool dp_retrieve_lttpr_cap(struct dc_link *link) allow_lttpr_non_transparent_mode = 1; } - /* - * Logic to determine LTTPR mode - */ link->lttpr_mode = LTTPR_MODE_NON_LTTPR; if (vbios_lttpr_enable && vbios_lttpr_interop) link->lttpr_mode = LTTPR_MODE_NON_TRANSPARENT; @@ -5177,6 +5171,18 @@ bool dp_retrieve_lttpr_cap(struct dc_link *link) link->dc->debug.dpia_debug.bits.force_non_lttpr) link->lttpr_mode = LTTPR_MODE_NON_LTTPR; #endif +} + +bool dp_retrieve_lttpr_cap(struct dc_link *link) +{ + uint8_t lttpr_dpcd_data[8]; + enum dc_status status = DC_ERROR_UNEXPECTED; + bool is_lttpr_present = false; + + memset(lttpr_dpcd_data, '\0', sizeof(lttpr_dpcd_data)); + + /* Logic to determine LTTPR mode*/ + determine_lttpr_mode(link); if (link->lttpr_mode == LTTPR_MODE_NON_TRANSPARENT || link->lttpr_mode == LTTPR_MODE_TRANSPARENT) { /* By reading LTTPR capability, RX assumes that we will enable @@ -5292,11 +5298,23 @@ static enum dc_status wa_try_to_wake_dprx(struct dc_link *link, uint64_t timeout uint64_t time_taken_ms = 0; enum dc_connection_type type = dc_connection_none; - status = core_link_read_dpcd( - link, - DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV, - &dpcd_data, - sizeof(dpcd_data)); + determine_lttpr_mode(link); + + /* Issue an AUX read to test DPRX responsiveness. If LTTPR is supported the first read is expected to + * be to determine LTTPR capabilities. Otherwise trying to read power state should be an innocuous AUX read. + */ + if (link->lttpr_mode == LTTPR_MODE_NON_TRANSPARENT || link->lttpr_mode == LTTPR_MODE_TRANSPARENT) + status = core_link_read_dpcd( + link, + DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV, + &dpcd_data, + sizeof(dpcd_data)); + else + status = core_link_read_dpcd( + link, + DP_SET_POWER, + &dpcd_data, + sizeof(dpcd_data)); if (status != DC_OK) { DC_LOG_WARNING("%s: Read DPCD LTTPR_CAP failed - try to toggle DPCD SET_POWER for %lld ms.", -- 2.36.1
