From patchwork Wed Jan 31 10:23:43 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arun R Murthy X-Patchwork-Id: 13539158 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1965FC47DDF for ; Wed, 31 Jan 2024 10:34:00 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0EFFB113B2C; Wed, 31 Jan 2024 10:33:55 +0000 (UTC) Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.65]) by gabe.freedesktop.org (Postfix) with ESMTPS id A1158113B14; Wed, 31 Jan 2024 10:33:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1706697233; x=1738233233; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=e/LvwFxrQNVCce+zkTCrQHdg7BYgjVpv+8lXG1cOAwg=; b=D+IijPV6em3fhZk1QfKMJWAJJFsy4vUkgcQWvJZn61I0LSUKNjig9PI+ f4gSuPuy2kE49Lg0qkSgA32ePF2vly9KB94HP3drZ8u/I1W+5W7OPMUVx wf/czhO16avyG3RSF3Fnai64XPORJhICa3obFCLFx3+odB3SOFjc/9iHj wZwL6YM9WHNBKcQeWoW9ev/MxYCTzgHHjzzuWwuS2Dn23ED9spN7lhHXP MU7k8EUOdneqtw55euOvBEoNcczOdIvOgjosxZB1g/mdG6rEdv/FRAWOp lUFHw8hp2wGSl8KTb68gHRNX+8tUqUQvzIBKCV9CsBKTVEwEvgdFnjM7U g==; X-IronPort-AV: E=McAfee;i="6600,9927,10969"; a="407278655" X-IronPort-AV: E=Sophos;i="6.05,231,1701158400"; d="scan'208";a="407278655" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jan 2024 02:33:52 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.05,231,1701158400"; d="scan'208";a="22747025" Received: from srr4-3-linux-106-armuthy.iind.intel.com ([10.190.238.56]) by fmviesa002.fm.intel.com with ESMTP; 31 Jan 2024 02:33:50 -0800 From: Arun R Murthy To: dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org Subject: [PATCHv2 1/2] drm/display/dp: Check for MSTM_CAP before MSTM_CTRL write Date: Wed, 31 Jan 2024 15:53:43 +0530 Message-Id: <20240131102344.1671929-1-arun.r.murthy@intel.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jani.nikula@intel.com Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" With DP2.1, multistream packetization and the underneth MST protocol will be required for SST. So check for MSTM_CAP to see if MST is really required and skip the MSTM_CTRL write so that we ensure that only the underneth protocol and the multistream packetization will be enabled and sink will not be confused by a corresponding dpcd write. Signed-off-by: Arun R Murthy --- drivers/gpu/drm/display/drm_dp_mst_topology.c | 38 +++++++++++-------- 1 file changed, 22 insertions(+), 16 deletions(-) diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c index 8ca01a6bf645..c5b3e51ea0c9 100644 --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -3666,12 +3666,14 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms mgr->mst_primary = mstb; drm_dp_mst_topology_get_mstb(mgr->mst_primary); - ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, - DP_MST_EN | - DP_UP_REQ_EN | - DP_UPSTREAM_IS_SRC); - if (ret < 0) - goto out_unlock; + if (drm_dp_read_mst_cap(mgr->aux, mgr->dpcd)) { + ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, + DP_MST_EN | + DP_UP_REQ_EN | + DP_UPSTREAM_IS_SRC); + if (ret < 0) + goto out_unlock; + } /* Write reset payload */ drm_dp_dpcd_write_payload(mgr, 0, 0, 0x3f); @@ -3684,7 +3686,8 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms mstb = mgr->mst_primary; mgr->mst_primary = NULL; /* this can fail if the device is gone */ - drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0); + if (drm_dp_read_mst_cap(mgr->aux, mgr->dpcd)) + drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0); ret = 0; mgr->payload_id_table_cleared = false; @@ -3724,8 +3727,9 @@ drm_dp_mst_topology_mgr_invalidate_mstb(struct drm_dp_mst_branch *mstb) void drm_dp_mst_topology_mgr_suspend(struct drm_dp_mst_topology_mgr *mgr) { mutex_lock(&mgr->lock); - drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, - DP_MST_EN | DP_UPSTREAM_IS_SRC); + if (drm_dp_read_mst_cap(mgr->aux, mgr->dpcd)) + drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, + DP_MST_EN | DP_UPSTREAM_IS_SRC); mutex_unlock(&mgr->lock); flush_work(&mgr->up_req_work); flush_work(&mgr->work); @@ -3773,13 +3777,15 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr, goto out_fail; } - ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, - DP_MST_EN | - DP_UP_REQ_EN | - DP_UPSTREAM_IS_SRC); - if (ret < 0) { - drm_dbg_kms(mgr->dev, "mst write failed - undocked during suspend?\n"); - goto out_fail; + if (drm_dp_read_mst_cap(mgr->aux, mgr->dpcd)) { + ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, + DP_MST_EN | + DP_UP_REQ_EN | + DP_UPSTREAM_IS_SRC); + if (ret < 0) { + drm_dbg_kms(mgr->dev, "mst write failed - undocked during suspend?\n"); + goto out_fail; + } } /* Some hubs forget their guids after they resume */