From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 442ACC4332F for ; Sun, 2 Oct 2022 22:52:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230219AbiJBWwj (ORCPT ); Sun, 2 Oct 2022 18:52:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56188 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230119AbiJBWvW (ORCPT ); Sun, 2 Oct 2022 18:51:22 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E430039BA1; Sun, 2 Oct 2022 15:50:37 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 89FC560F19; Sun, 2 Oct 2022 22:50:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF559C433B5; Sun, 2 Oct 2022 22:50:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664751030; bh=lPKcDtfBkw81BZ1ZRxlUP0s5ImWOvfOBFzo7y33aLBc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bAKM8luaq3ivdRSTm8NhKTBeYtBaf+FrwaDWP4e3VGdjotM9NVRewR2aqV62vzNi8 kLkyleTAdnzrKFcUT4yRin9U2WxppVooH3pjQeYrlbCeH63Gz8mUd+024TA4uspYD6 wCny7sprtCAZbIY3hKD9dcr6jgYovdl2DNkVpcDektZKYeu5/kWb8rKwGF0EuZ1DYO zoVo3l9+SaGiX1JHmG1DQSb0u4vwYHDqBKVB+4/dR4tfoECVC8U+hC6j/xvPIBXv4B C9ZDo1kizV6tZmtgMNrFMKr082nxuImdtOeOvJGIE8bhQAhLJkeJy49J+gqxKwNNUO 9LomXQ8GBcLGw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Michael Strauss , George Shen , Wayne Lin , Daniel Wheeler , Alex Deucher , Sasha Levin , harry.wentland@amd.com, sunpeng.li@amd.com, Rodrigo.Siqueira@amd.com, christian.koenig@amd.com, Xinhui.Pan@amd.com, airlied@gmail.com, daniel@ffwll.ch, wenjing.liu@amd.com, george.shen@amd.com, Jun.Lei@amd.com, Jimmy.Kizito@amd.com, mikita.lipski@amd.com, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 5.19 24/29] drm/amd/display: Assume an LTTPR is always present on fixed_vs links Date: Sun, 2 Oct 2022 18:49:17 -0400 Message-Id: <20221002224922.238837-24-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221002224922.238837-1-sashal@kernel.org> References: <20221002224922.238837-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michael Strauss [ Upstream commit 29956d0fded036a570bd8e7d4ea4b1a1730307d2 ] [WHY] LTTPRs can in very rare instsances fail to increment DPCD LTTPR count. This results in aux-i LTTPR requests to be sent to the wrong DPCD address, which causes link training failure. [HOW] Override internal repeater count if fixed_vs flag is set for a given link Reviewed-by: George Shen Acked-by: Wayne Lin Signed-off-by: Michael Strauss Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher Signed-off-by: Sasha Levin --- drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 8 ++++++++ 1 file changed, 8 insertions(+) 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 a4fc9a6c850e..0c52506b367d 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 @@ -5211,6 +5211,14 @@ bool dp_retrieve_lttpr_cap(struct dc_link *link) lttpr_dpcd_data[DP_PHY_REPEATER_128B132B_RATES - DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV]; + /* If this chip cap is set, at least one retimer must exist in the chain + * Override count to 1 if we receive a known bad count (0 or an invalid value) */ + if (link->chip_caps & EXT_DISPLAY_PATH_CAPS__DP_FIXED_VS_EN && + (dp_convert_to_count(link->dpcd_caps.lttpr_caps.phy_repeater_cnt) == 0)) { + ASSERT(0); + link->dpcd_caps.lttpr_caps.phy_repeater_cnt = 0x80; + } + /* Attempt to train in LTTPR transparent mode if repeater count exceeds 8. */ is_lttpr_present = (link->dpcd_caps.lttpr_caps.max_lane_count > 0 && link->dpcd_caps.lttpr_caps.max_lane_count <= 4 && -- 2.35.1