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 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 6632BCCF9E0 for ; Fri, 24 Oct 2025 19:22:54 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id F3BCB10EB30; Fri, 24 Oct 2025 19:22:50 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=linux.dev header.i=@linux.dev header.b="mbJ0Rthd"; dkim-atps=neutral X-Greylist: delayed 319 seconds by postgrey-1.36 at gabe; Fri, 24 Oct 2025 19:22:48 UTC Received: from out-186.mta0.migadu.com (out-186.mta0.migadu.com [91.218.175.186]) by gabe.freedesktop.org (Postfix) with ESMTPS id 558ED10E224 for ; Fri, 24 Oct 2025 19:22:48 +0000 (UTC) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1761333450; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=F/WrJTDCbjNqXN4i/GaEE8YS8TrIdiKbp038ohCvnOc=; b=mbJ0Rthd8AZmKwRv4lef9+aiFolHMxkakI/npPVUBOcdu5mv3ZdxWpri4dgUt8bypW4ZmE /3Mf/6SQexFCGTYD14HR6yvlhqn346ZxnpBUN2yvc0B69L2ZLiJietvjeVu8kd+VHSyHNO xT/I56yWliOPzOhsz48RpLTziZGHHJQ= From: Sean Anderson To: Laurent Pinchart , Tomi Valkeinen , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , dri-devel@lists.freedesktop.org Cc: linux-kernel@vger.kernel.org, David Airlie , Hyun Kwon , Simona Vetter , Michal Simek , linux-arm-kernel@lists.infradead.org, Sean Anderson Subject: [PATCH 2/3] drm: zynqmp_dp: Use smp_load/store for status Date: Fri, 24 Oct 2025 15:17:06 -0400 Message-Id: <20251024191707.2310589-3-sean.anderson@linux.dev> In-Reply-To: <20251024191707.2310589-1-sean.anderson@linux.dev> References: <20251024191707.2310589-1-sean.anderson@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" dp->status is read asynchronously by the AUX bus. Therefore, all reads outside of dp->lock must be atomic. Similarly, writes must be atomic as well. Reads with dp->lock held do not need to be atomic. Fixes: a7d5eeaa57d7 ("drm: zynqmp_dp: Add locking") Signed-off-by: Sean Anderson --- drivers/gpu/drm/xlnx/zynqmp_dp.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c index f39c78b08e6a..caf2e0ce3644 100644 --- a/drivers/gpu/drm/xlnx/zynqmp_dp.c +++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c @@ -1111,7 +1111,7 @@ zynqmp_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) return msg->size; } - if (dp->status == connector_status_disconnected) { + if (READ_ONCE(dp->status) == connector_status_disconnected) { dev_dbg(dp->dev, "no connected aux device\n"); if (dp->ignore_aux_errors) goto fake_response; @@ -1697,7 +1697,7 @@ static enum drm_connector_status __zynqmp_dp_bridge_detect(struct zynqmp_dp *dp) } if (state & ZYNQMP_DP_INTERRUPT_SIGNAL_STATE_HPD) { - dp->status = connector_status_connected; + WRITE_ONCE(dp->status, connector_status_connected); ret = drm_dp_dpcd_read(&dp->aux, 0x0, dp->dpcd, sizeof(dp->dpcd)); if (ret < 0) { @@ -1716,7 +1716,7 @@ static enum drm_connector_status __zynqmp_dp_bridge_detect(struct zynqmp_dp *dp) } disconnected: - dp->status = connector_status_disconnected; + WRITE_ONCE(dp->status, connector_status_disconnected); return connector_status_disconnected; } -- 2.35.1.1320.gc452695387.dirty