[PATCH 350/459] drm/amd/display: do not power on eDP power rail early

Alex Deucher alexdeucher at gmail.com
Mon Jun 17 19:44:51 UTC 2019

From: Anthony Koo <Anthony.Koo at amd.com>

Modern Standby may toggle display adapter state between D0
and D3 state unpredictably.
But events that cause transition to D0 are not always resulting
in a display light up scenario.

Modern eDP panels should be able to power on panel logic
quickly upon VDD going high. Based on spec, the T3 time
between VDD on and HPD high can be between 0 and 80 ms.

Doing any tricky sorts of optimization by powering on panel
VDD early during D0 transition on can negatively impact other
features due to unnecessary power drain and toggling when
final system state does not intend for the panel to be lit up.

We need OEMs to source higher end panels that have T3 time
close to 0 if they want quick S3/Modern Standby resume times.

Remove panel VDD power on in init_hw

Signed-off-by: Anthony Koo <Anthony.Koo at amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng at amd.com>
Acked-by: Leo Li <sunpeng.li at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
 drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
index 2a34447112e9..f6e25f75a0a9 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
@@ -547,9 +547,6 @@ static void dcn20_init_hw(struct dc *dc)
 			struct dc_link *link = dc->links[i];
-			if (link->link_enc->connector.id == CONNECTOR_ID_EDP)
-				dc->hwss.edp_power_control(link, true);

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