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drm/amd/display: Work around bad DPCD state on link loss 

[Why]
This display doesn't properly indicate link loss through DPCD bits such
as CR_DONE / CHANNEL_EQ_DONE / SYMBOL_LOCKED / INTERLANE_ALIGN_DONE,
which all remain set.

In addition, DPCD200Eh doesn't match the value of DPCD204h in all cases.

For these reasons, we can miss re-training the link, since we don't
properly detect link loss with this display.

[Why]
Add display-specific workaround to read DPCD204h, so that we can detect
link loss based on 128b132b-specific status bits in this register.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Wenjing Liu <wenjing.liu@amd.com>
Acked-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Ilya Bakoulin <ilya.bakoulin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Ilya Bakoulin 2023-06-02 17:01:23 -04:00 committed by Alex Deucher
parent 2036b34d4a
commit 2faa3653d6
2 changed files with 27 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/gpu/drm/amd/display/dc/dc.h
View File

@ -1525,6 +1525,7 @@ struct dc_link {
bool dpia_forced_tbt3_mode;
bool dongle_mode_timing_override;
bool blank_stream_on_ocs_change;
bool read_dpcd204h_on_irq_hpd;
} wa_flags;
struct link_mst_stream_allocation_table mst_stream_alloc_table;

26
drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_irq_handler.c
View File

@ -208,6 +208,25 @@ void dp_handle_link_loss(struct dc_link *link)
}
}
static void read_dpcd204h_on_irq_hpd(struct dc_link *link, union hpd_irq_data *irq_data)
{
enum dc_status retval;
union lane_align_status_updated dpcd_lane_status_updated;
retval = core_link_read_dpcd(
link,
DP_LANE_ALIGN_STATUS_UPDATED,
&dpcd_lane_status_updated.raw,
sizeof(union lane_align_status_updated));
if (retval == DC_OK) {
irq_data->bytes.lane_status_updated.bits.EQ_INTERLANE_ALIGN_DONE_128b_132b =
dpcd_lane_status_updated.bits.EQ_INTERLANE_ALIGN_DONE_128b_132b;
irq_data->bytes.lane_status_updated.bits.CDS_INTERLANE_ALIGN_DONE_128b_132b =
dpcd_lane_status_updated.bits.CDS_INTERLANE_ALIGN_DONE_128b_132b;
}
}
enum dc_status dp_read_hpd_rx_irq_data(
struct dc_link *link,
union hpd_irq_data *irq_data)
@ -249,6 +268,13 @@ enum dc_status dp_read_hpd_rx_irq_data(
irq_data->bytes.lane23_status.raw = tmp[DP_LANE2_3_STATUS_ESI - DP_SINK_COUNT_ESI];
irq_data->bytes.lane_status_updated.raw = tmp[DP_LANE_ALIGN_STATUS_UPDATED_ESI - DP_SINK_COUNT_ESI];
irq_data->bytes.sink_status.raw = tmp[DP_SINK_STATUS_ESI - DP_SINK_COUNT_ESI];
/*
* This display doesn't have correct values in DPCD200Eh.
* Read and check DPCD204h instead.
*/
if (link->wa_flags.read_dpcd204h_on_irq_hpd)
read_dpcd204h_on_irq_hpd(link, irq_data);
}
return retval;