From: Zhikai Zhai Date: Tue, 29 Jul 2025 09:39:54 +0000 (+0800) Subject: drm/amd/display: Modify the link training policy X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=0bfcb56e8b074c9f013f357e799c446a9dbc1fad;p=users%2Fhch%2Fmisc.git drm/amd/display: Modify the link training policy [Why&How] Currently fallback to low link rate if the link training fails once on USB4. It may cause the bandwidth couldn't satisfy the requirement of streams. Modify the policy to do training retry in the previous few times, only do fallback at the last time. Reviewed-by: Meenakshikumar Somasundaram Signed-off-by: Zhikai Zhai Signed-off-by: Ray Wu Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher --- diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.c index 134093ce5a8e..08e2b572e0ff 100644 --- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.c +++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.c @@ -1729,6 +1729,15 @@ bool perform_link_training_with_retries( break; } + if (link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA && + stream->signal == SIGNAL_TYPE_DISPLAY_PORT_MST && + !link->dc->config.enable_dpia_pre_training) { + if (j == (attempts - 1)) + do_fallback = true; + else + do_fallback = false; + } + if (j == (attempts - 1)) { DC_LOG_WARNING( "%s: Link(%d) training attempt %u of %d failed @ rate(%d) x lane(%d) @ spread = %x : fail reason:(%d)\n",