From 6ebdaf20fc4dd98e7573dc2a926c81afc8ac7870 Mon Sep 17 00:00:00 2001 From: Lewis Huang Date: Mon, 8 Aug 2022 13:20:16 +0800 Subject: [PATCH] drm/amd/display: Refine aux transaction before retrieve caps [Why] LTTPR caps will read fail if aux channel is not active. [How] 1.Perform 600 read upto 10 retry with 1ms delay in between. 2.If fail, return false and trigger another retry detection. 3.If pass, read LTTPR caps in retrieve link caps. Reviewed-by: Jimmy Kizito Acked-by: Brian Chang Signed-off-by: Lewis Huang Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 45 ++++++++++++++++++------ 1 file changed, 34 insertions(+), 11 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 f92bbc8..4c04b5f 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 @@ -5275,6 +5275,7 @@ static bool retrieve_link_cap(struct dc_link *link) union dp_downstream_port_present ds_port = { 0 }; enum dc_status status = DC_ERROR_UNEXPECTED; uint32_t read_dpcd_retry_cnt = 3; + uint32_t aux_channel_retry_cnt = 0; int i; struct dp_sink_hw_fw_revision dp_hw_fw_revision; const uint32_t post_oui_delay = 30; // 30ms @@ -5302,21 +5303,43 @@ static bool retrieve_link_cap(struct dc_link *link) status = wa_try_to_wake_dprx(link, timeout_ms); } + while (status != DC_OK && aux_channel_retry_cnt < 10) { + status = core_link_read_dpcd(link, DP_SET_POWER, + &dpcd_power_state, sizeof(dpcd_power_state)); + + /* Delay 1 ms if AUX CH is in power down state. Based on spec + * section 2.3.1.2, if AUX CH may be powered down due to + * write to DPCD 600h = 2. Sink AUX CH is monitoring differential + * signal and may need up to 1 ms before being able to reply. + */ + if (status != DC_OK || dpcd_power_state == DP_SET_POWER_D3) { + udelay(1000); + aux_channel_retry_cnt++; + } + } + + /* If aux channel is not active, return false and trigger another detect*/ + if (status != DC_OK) { + dpcd_power_state = DP_SET_POWER_D0; + status = core_link_write_dpcd( + link, + DP_SET_POWER, + &dpcd_power_state, + sizeof(dpcd_power_state)); + + dpcd_power_state = DP_SET_POWER_D3; + status = core_link_write_dpcd( + link, + DP_SET_POWER, + &dpcd_power_state, + sizeof(dpcd_power_state)); + return false; + } + is_lttpr_present = dp_retrieve_lttpr_cap(link); /* Read DP tunneling information. */ status = dpcd_get_tunneling_device_data(link); - status = core_link_read_dpcd(link, DP_SET_POWER, - &dpcd_power_state, sizeof(dpcd_power_state)); - - /* Delay 1 ms if AUX CH is in power down state. Based on spec - * section 2.3.1.2, if AUX CH may be powered down due to - * write to DPCD 600h = 2. Sink AUX CH is monitoring differential - * signal and may need up to 1 ms before being able to reply. - */ - if (status != DC_OK || dpcd_power_state == DP_SET_POWER_D3) - udelay(1000); - dpcd_set_source_specific_data(link); /* Sink may need to configure internals based on vendor, so allow some * time before proceeding with possibly vendor specific transactions -- 2.7.4