From patchwork Fri Aug 9 19:35:54 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Anderson X-Patchwork-Id: 13759211 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 D1B53C52D7C for ; Fri, 9 Aug 2024 19:38:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=oK3GkwlYIbgKa5E/wcr/BC9b4B3l2udsFuim2xq4G6g=; b=Tznmpt4dL7PIYIA6vDnga2OttL yh18XjYyO/Rud82w4/GSH2bGQwa0swC486UivcSVABkyuecBgLcFFo4fnUl8gpJS9CycOonUEoygi 4qgwREL8CPncoD+Mhp5IC+umcnjWdNxphjEtaNW9H8z1v8ypifNHkZqWTgR4C5M8QtIQ2eDX4aCEI votjuQTbteWIvLn6+Fq5u7m1+5svZ1SNeo2bpLgOmsNoU+b/uamSlwcE5jK7az1yyhAVk4P0u90XJ G4v1y/k4hPgsvRt1Qk+1WPKIaZaVcxm2KcynIKHCC1qLF3NieRuEtA+aeUWs9aOWbH2KtbtBfWJri wJMNSyCg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1scVRA-0000000CNuA-1vYW; Fri, 09 Aug 2024 19:38:08 +0000 Received: from out-178.mta1.migadu.com ([95.215.58.178]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1scVPW-0000000CNLI-0uZy for linux-arm-kernel@lists.infradead.org; Fri, 09 Aug 2024 19:36:28 +0000 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=1723232183; 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=oK3GkwlYIbgKa5E/wcr/BC9b4B3l2udsFuim2xq4G6g=; b=NbRyz7RnF3xFMrm9ajZjqSRV7IRnkXVtqP44r7fxyRPE7Rm/iNQvh8oTKhuxCqXPSmMZD7 ApYqn2y7xtEUgwTM20tVrjSa96Z66akv/brrEKBeNVS9vMVZ5/3OpWQsQUdkP/FMcea0t8 kdGJE8I4uZhBS8uWQdEew8jUuBoeyn0= From: Sean Anderson To: Laurent Pinchart , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , dri-devel@lists.freedesktop.org Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, David Airlie , Michal Simek , Daniel Vetter , Tomi Valkeinen , Sean Anderson Subject: [PATCH v6 2/8] drm: zynqmp_dp: Add locking Date: Fri, 9 Aug 2024 15:35:54 -0400 Message-Id: <20240809193600.3360015-3-sean.anderson@linux.dev> In-Reply-To: <20240809193600.3360015-1-sean.anderson@linux.dev> References: <20240809193600.3360015-1-sean.anderson@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240809_123626_577340_FA9AE6FA X-CRM114-Status: GOOD ( 18.05 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Add some locking to prevent the IRQ/workers/bridge API calls from stepping on each other's toes. This lock protects: - Non-atomic registers configuring the link. That is, everything but the IRQ registers (since these are accessed in an atomic fashion), and the DP AUX registers (since these don't affect the link). We also access AUX while holding this lock, so it would be very tricky to support. - Link configuration. This is effectively everything in zynqmp_dp which isn't read-only after probe time. So from next_bridge onward. This lock is designed to protect configuration changes so we don't have to do anything tricky. Configuration should never be in the hot path, so I'm not worried about performance. Signed-off-by: Sean Anderson --- (no changes since v2) Changes in v2: - Split off the HPD IRQ work into another commit - Expand the commit message drivers/gpu/drm/xlnx/zynqmp_dp.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c index 129beac4c073..abfccd8bb5a7 100644 --- a/drivers/gpu/drm/xlnx/zynqmp_dp.c +++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c @@ -280,6 +280,7 @@ struct zynqmp_dp_config { * @dpsub: Display subsystem * @iomem: device I/O memory for register access * @reset: reset controller + * @lock: Mutex protecting this struct and register access (but not AUX) * @irq: irq * @bridge: DRM bridge for the DP encoder * @next_bridge: The downstream bridge @@ -294,11 +295,16 @@ struct zynqmp_dp_config { * @link_config: common link configuration between IP core and sink device * @mode: current mode between IP core and sink device * @train_set: set of training data + * + * @lock covers the link configuration in this struct and the device's + * registers. It does not cover @aux. It is not strictly required for any of + * the members which are only modified at probe/remove time (e.g. @dev). */ struct zynqmp_dp { struct drm_dp_aux aux; struct drm_bridge bridge; struct work_struct hpd_work; + struct mutex lock; struct drm_bridge *next_bridge; struct device *dev; @@ -1386,8 +1392,10 @@ zynqmp_dp_bridge_mode_valid(struct drm_bridge *bridge, } /* Check with link rate and lane count */ + mutex_lock(&dp->lock); rate = zynqmp_dp_max_rate(dp->link_config.max_rate, dp->link_config.max_lanes, dp->config.bpp); + mutex_unlock(&dp->lock); if (mode->clock > rate) { dev_dbg(dp->dev, "filtered mode %s for high pixel rate\n", mode->name); @@ -1414,6 +1422,7 @@ static void zynqmp_dp_bridge_atomic_enable(struct drm_bridge *bridge, pm_runtime_get_sync(dp->dev); + mutex_lock(&dp->lock); zynqmp_dp_disp_enable(dp, old_bridge_state); /* @@ -1474,6 +1483,7 @@ static void zynqmp_dp_bridge_atomic_enable(struct drm_bridge *bridge, zynqmp_dp_write(dp, ZYNQMP_DP_SOFTWARE_RESET, ZYNQMP_DP_SOFTWARE_RESET_ALL); zynqmp_dp_write(dp, ZYNQMP_DP_MAIN_STREAM_ENABLE, 1); + mutex_unlock(&dp->lock); } static void zynqmp_dp_bridge_atomic_disable(struct drm_bridge *bridge, @@ -1481,6 +1491,7 @@ static void zynqmp_dp_bridge_atomic_disable(struct drm_bridge *bridge, { struct zynqmp_dp *dp = bridge_to_dp(bridge); + mutex_lock(&dp->lock); dp->enabled = false; cancel_work(&dp->hpd_work); zynqmp_dp_write(dp, ZYNQMP_DP_MAIN_STREAM_ENABLE, 0); @@ -1491,6 +1502,7 @@ static void zynqmp_dp_bridge_atomic_disable(struct drm_bridge *bridge, zynqmp_dp_write(dp, ZYNQMP_DP_TX_AUDIO_CONTROL, 0); zynqmp_dp_disp_disable(dp, old_bridge_state); + mutex_unlock(&dp->lock); pm_runtime_put_sync(dp->dev); } @@ -1533,6 +1545,8 @@ static enum drm_connector_status zynqmp_dp_bridge_detect(struct drm_bridge *brid u32 state, i; int ret; + mutex_lock(&dp->lock); + /* * This is from heuristic. It takes some delay (ex, 100 ~ 500 msec) to * get the HPD signal with some monitors. @@ -1560,11 +1574,13 @@ static enum drm_connector_status zynqmp_dp_bridge_detect(struct drm_bridge *brid dp->num_lanes); dp->status = connector_status_connected; + mutex_unlock(&dp->lock); return connector_status_connected; } disconnected: dp->status = connector_status_disconnected; + mutex_unlock(&dp->lock); return connector_status_disconnected; } @@ -1725,6 +1741,7 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub) dp->dev = &pdev->dev; dp->dpsub = dpsub; dp->status = connector_status_disconnected; + mutex_init(&dp->lock); INIT_WORK(&dp->hpd_work, zynqmp_dp_hpd_work_func); @@ -1838,4 +1855,5 @@ void zynqmp_dp_remove(struct zynqmp_dpsub *dpsub) zynqmp_dp_phy_exit(dp); zynqmp_dp_reset(dp, true); + mutex_destroy(&dp->lock); }