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 CA655C433F5 for ; Mon, 10 Oct 2022 00:20:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232561AbiJJAUk (ORCPT ); Sun, 9 Oct 2022 20:20:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43850 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232060AbiJJAS6 (ORCPT ); Sun, 9 Oct 2022 20:18:58 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 133D2107; Sun, 9 Oct 2022 16:54:01 -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 A5DFE60D17; Sun, 9 Oct 2022 23:54:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C3714C43141; Sun, 9 Oct 2022 23:53:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1665359640; bh=nHlhI1QWXEppbMON++/kcW8SsBgmXCnr015giDmAqlE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YSDpb5FuYLfQkOUD5PsqxUOmbFtqwNsrlQIdidq8LBmLnkzkgDce1e/9FzphglVYn HVASKHAGQnmVVJOPMGQso1iJBCBhCPwEB3uPlyFB3WhYBwWaO6z6cqJf9fj4Cfi5nY HSShh5XNtvKpxs44vcWOePr12zV8IY+W9Ry7PXG4jTgbMLrUGd8niMoBZYq7gMLWAd SFq3FGxuVtfn0VeBmne/GKaw+5An8Je3Y0R4Ju/c4MU/2+yJ/uxeBEcPODokEUzO15 Mw8AK5+8KK3G/N8Ld25a2PHijPpJe3cCZfYLTGsRM/RZ488tJsmv1CfZgaihsnSZTm HtpBCg7t5eGEw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Khaled Almahallawy , Imre Deak , Jani Nikula , Or Cochvi , Sasha Levin , airlied@gmail.com, daniel@ffwll.ch, lyude@redhat.com, tzimmermann@suse.de, ville.syrjala@linux.intel.com, dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 5.19 32/36] drm/dp: Don't rewrite link config when setting phy test pattern Date: Sun, 9 Oct 2022 19:52:18 -0400 Message-Id: <20221009235222.1230786-32-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221009235222.1230786-1-sashal@kernel.org> References: <20221009235222.1230786-1-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: Khaled Almahallawy [ Upstream commit 7b4d8db657192066bc6f1f6635d348413dac1e18 ] The sequence for Source DP PHY CTS automation is [2][1]: 1- Emulate successful Link Training(LT) 2- Short HPD and change link rates and number of lanes by LT. (This is same flow for Link Layer CTS) 3- Short HPD and change PHY test pattern and swing/pre-emphasis levels (This step should not trigger LT) The problem is with DP PHY compliance setup as follow: [DPTX + on board LTTPR]------Main Link--->[Scope] ^ | | | | | ----------Aux Ch------>[Aux Emulator] At step 3, before writing TRAINING_LANEx_SET/LINK_QUAL_PATTERN_SET to declare the pattern/swing requested by scope, we write link config in LINK_BW_SET/LANE_COUNT_SET on a port that has LTTPR. As LTTPR snoops aux transaction, LINK_BW_SET/LANE_COUNT_SET writes indicate a LT will start [Check DP 2.0 E11 -Sec 3.6.8.2 & 3.6.8.6.3], and LTTPR will reset the link and stop sending DP signals to DPTX/Scope causing the measurements to fail. Note that step 3 will not trigger LT and DP link will never recovered by the Aux Emulator/Scope. The reset of link can be tested with a monitor connected to LTTPR port simply by writing to LINK_BW_SET or LANE_COUNT_SET as follow igt/tools/dpcd_reg write --offset=0x100 --value 0x14 --device=2 OR printf '\x14' | sudo dd of=/dev/drm_dp_aux2 bs=1 count=1 conv=notrunc seek=$((0x100)) This single aux write causes the screen to blank, sending short HPD to DPTX, setting LINK_STATUS_UPDATE = 1 in DPCD 0x204, and triggering LT. As stated in [1]: "Before any TX electrical testing can be performed, the link between a DPTX and DPRX (in this case, a piece of test equipment), including all LTTPRs within the path, shall be trained as defined in this Standard." In addition, changing Phy pattern/Swing/Pre-emphasis (Step 3) uses the same link rate and lane count applied on step 2, so no need to redo LT. The fix is to not rewrite link config in step 3, and just writes TRAINING_LANEx_SET and LINK_QUAL_PATTERN_SET [1]: DP 2.0 E11 - 3.6.11.1 LTTPR DPTX_PHY Electrical Compliance [2]: Configuring UnigrafDPTC Controller - Automation Test Sequence https://www.keysight.com/us/en/assets/9922-01244/help-files/ D9040DPPC-DisplayPort-Test-Software-Online-Help-latest.chm Cc: Imre Deak Cc: Jani Nikula Cc: Or Cochvi Signed-off-by: Khaled Almahallawy Signed-off-by: Jani Nikula Link: https://patchwork.freedesktop.org/patch/msgid/20220916054900.415804-1-khaled.almahallawy@intel.com Signed-off-by: Sasha Levin --- drivers/gpu/drm/display/drm_dp_helper.c | 9 --------- 1 file changed, 9 deletions(-) diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c index e7c22c2ca90c..f27cd710bc86 100644 --- a/drivers/gpu/drm/display/drm_dp_helper.c +++ b/drivers/gpu/drm/display/drm_dp_helper.c @@ -2636,17 +2636,8 @@ int drm_dp_set_phy_test_pattern(struct drm_dp_aux *aux, struct drm_dp_phy_test_params *data, u8 dp_rev) { int err, i; - u8 link_config[2]; u8 test_pattern; - link_config[0] = drm_dp_link_rate_to_bw_code(data->link_rate); - link_config[1] = data->num_lanes; - if (data->enhanced_frame_cap) - link_config[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN; - err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, link_config, 2); - if (err < 0) - return err; - test_pattern = data->phy_pattern; if (dp_rev < 0x12) { test_pattern = (test_pattern << 2) & -- 2.35.1