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 DDD24ECAAD5 for ; Mon, 29 Aug 2022 13:48:22 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id EFB8E10F29F; Mon, 29 Aug 2022 13:48:16 +0000 (UTC) Received: from wout4-smtp.messagingengine.com (wout4-smtp.messagingengine.com [64.147.123.20]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6839F10F278 for ; Mon, 29 Aug 2022 13:48:01 +0000 (UTC) Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.west.internal (Postfix) with ESMTP id 05D5B3200645; Mon, 29 Aug 2022 09:47:59 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute3.internal (MEProxy); Mon, 29 Aug 2022 09:48:01 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cerno.tech; h=cc :cc:content-transfer-encoding:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:sender :subject:subject:to:to; s=fm3; t=1661780879; x=1661867279; bh=RB N8wvNkGXXWpA5NSb3ISMxUFiqyLWKa2TlSyoSllxQ=; b=oEKwL0j2FKNW4xffBr ZTBeTj34Q7fjaPQx7JxCp4j7LqyUtj0osYP/cRNkz/y+zeAyxZXTdQHfBNYHMenI rEbV1nVddsx4QVn5BRzn5AQ6zT97KgYkwEjQz569+N4ADnayMsS94tEnUUdu/E4l ZmWDi/91OYoV9bM0+nn0MhY4D5hvGqVpfwJKerkMqYNC0/za0xe8RFENebs77UgT etcEazGBiB1VqKurVvc2eR+aG1U4n33FP8pAt72XZ0968PZcEv8UE9ll7okbxSI7 p4xD79sp+2/a202ffXxpZUe/F1nzlrDphbI/mjzFVAz/1A7Fs3SiHev4fz8w0zLs N0eA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm1; t=1661780879; x=1661867279; bh=RBN8wvNkGXXWp A5NSb3ISMxUFiqyLWKa2TlSyoSllxQ=; b=vCSD9wKZ+S1tk6bIoDLWYoY8b6BnU fqfcWcvL6i8RNy5lLvylgEjS98RT/0kusKhudplx/EfAL6VqzRnmWO0R2cqOSaC1 +uTw9UtVBPo/hJLAKHO7UJvDGHm7k8MQycMjpo2Y5YWEp3rSbW8uR3ZL2UsnNKed N2sAsOtnx+xY9KdG51XLYmjiXofMhV8zkM128/dqIN8KRlaLVV2/7WLgwJ7C7yGK xeR7O1u+dzMBJ1VF0vxlAlikWF7Lu0Li71OFLSRQSga043xo3tBo+TwWrDR5N7j/ 5BzHTHTmN/prwKp+5aVdBLNZ4KDX3fS6WKVk0fncA+JTUIxjvZXeP8D3Q== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvfedrvdekuddgjedtucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvvefufffkofgjfhgggfestdekredtredttdenucfhrhhomhepofgrgihi mhgvucftihhprghrugcuoehmrgigihhmvgestggvrhhnohdrthgvtghhqeenucggtffrrg htthgvrhhnpeelkeefteduhfekjeeihfetudfguedvveekkeetteekhfekhfdtlefgfedu vdejhfenucevlhhushhtvghrufhiiigvpedunecurfgrrhgrmhepmhgrihhlfhhrohhmpe hmrgigihhmvgestggvrhhnohdrthgvtghh X-ME-Proxy: Feedback-ID: i8771445c:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Mon, 29 Aug 2022 09:47:58 -0400 (EDT) From: Maxime Ripard To: Maarten Lankhorst , Thomas Zimmermann , Maxime Ripard , Daniel Vetter , David Airlie Subject: [PATCH v4 3/8] drm/vc4: hdmi: Remove mutex in detect Date: Mon, 29 Aug 2022 15:47:26 +0200 Message-Id: <20220829134731.213478-4-maxime@cerno.tech> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220829134731.213478-1-maxime@cerno.tech> References: <20220829134731.213478-1-maxime@cerno.tech> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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: , Cc: Dom Cobley , Tim Gover , Dave Stevenson , dri-devel@lists.freedesktop.org, Phil Elwell Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" We recently introduced a new mutex to protect concurrent execution of ALSA and KMS hooks, and the concurrent access to some of vc4_hdmi fields. However, using it in the detect hook was creating a reentrency issue with CEC code. Indeed, calling cec_s_phys_addr_from_edid from detect might call the CEC adap_enable hook with the lock held, eventually resulting in a deadlock. Since we didn't really need to protect anything at the moment in the CEC code, the decision was made to ignore the mutex in those CEC hooks, working around the issue. However, we can have the same thing happening if we end up triggering a mode set from the detect callback, for example using drm_atomic_helper_connector_hdmi_reset_link(). Since we don't really need to protect anything in detect either, let's just drop the lock in detect, and add it again in CEC. Signed-off-by: Maxime Ripard --- drivers/gpu/drm/vc4/vc4_hdmi.c | 88 +++++++++++++--------------------- drivers/gpu/drm/vc4/vc4_hdmi.h | 10 +--- 2 files changed, 34 insertions(+), 64 deletions(-) diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index faf52c20b95b..b786645eaeb7 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -279,7 +279,16 @@ vc4_hdmi_connector_detect(struct drm_connector *connector, bool force) struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector); bool connected = false; - mutex_lock(&vc4_hdmi->mutex); + /* + * NOTE: This function should really take vc4_hdmi->mutex, but + * doing so results in reentrancy issues since + * cec_s_phys_addr_from_edid might call .adap_enable, which + * leads to that funtion being called with our mutex held. + * + * Concurrency isn't an issue at the moment since we don't share + * any state with any of the other frameworks so we can ignore + * the lock for now. + */ WARN_ON(pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev)); @@ -304,13 +313,11 @@ vc4_hdmi_connector_detect(struct drm_connector *connector, bool force) vc4_hdmi_enable_scrambling(&vc4_hdmi->encoder.base); pm_runtime_put(&vc4_hdmi->pdev->dev); - mutex_unlock(&vc4_hdmi->mutex); return connector_status_connected; } cec_phys_addr_invalidate(vc4_hdmi->cec_adap); pm_runtime_put(&vc4_hdmi->pdev->dev); - mutex_unlock(&vc4_hdmi->mutex); return connector_status_disconnected; } @@ -320,14 +327,21 @@ static int vc4_hdmi_connector_get_modes(struct drm_connector *connector) int ret = 0; struct edid *edid; - mutex_lock(&vc4_hdmi->mutex); + /* + * NOTE: This function should really take vc4_hdmi->mutex, but + * doing so results in reentrancy issues since + * cec_s_phys_addr_from_edid might call .adap_enable, which + * leads to that funtion being called with our mutex held. + * + * Concurrency isn't an issue at the moment since we don't share + * any state with any of the other frameworks so we can ignore + * the lock for now. + */ edid = drm_get_edid(connector, vc4_hdmi->ddc); cec_s_phys_addr_from_edid(vc4_hdmi->cec_adap, edid); - if (!edid) { - ret = -ENODEV; - goto out; - } + if (!edid) + return -ENODEV; drm_connector_update_edid_property(connector, edid); ret = drm_add_edid_modes(connector, edid); @@ -345,9 +359,6 @@ static int vc4_hdmi_connector_get_modes(struct drm_connector *connector) } } -out: - mutex_unlock(&vc4_hdmi->mutex); - return ret; } @@ -2663,17 +2674,6 @@ static int vc4_hdmi_cec_enable(struct cec_adapter *adap) int ret; int idx; - /* - * NOTE: This function should really take vc4_hdmi->mutex, but doing so - * results in a reentrancy since cec_s_phys_addr_from_edid() called in - * .detect or .get_modes might call .adap_enable, which leads to this - * function being called with that mutex held. - * - * Concurrency is not an issue for the moment since we don't share any - * state with KMS, so we can ignore the lock for now, but we need to - * keep it in mind if we were to change that assumption. - */ - if (!drm_dev_enter(drm, &idx)) /* * We can't return an error code, because the CEC @@ -2688,6 +2688,8 @@ static int vc4_hdmi_cec_enable(struct cec_adapter *adap) return ret; } + mutex_lock(&vc4_hdmi->mutex); + spin_lock_irqsave(&vc4_hdmi->hw_lock, flags); val = HDMI_READ(HDMI_CEC_CNTRL_5); @@ -2722,6 +2724,7 @@ static int vc4_hdmi_cec_enable(struct cec_adapter *adap) spin_unlock_irqrestore(&vc4_hdmi->hw_lock, flags); + mutex_unlock(&vc4_hdmi->mutex); drm_dev_exit(idx); return 0; @@ -2742,16 +2745,7 @@ static int vc4_hdmi_cec_disable(struct cec_adapter *adap) */ return 0; - /* - * NOTE: This function should really take vc4_hdmi->mutex, but doing so - * results in a reentrancy since cec_s_phys_addr_from_edid() called in - * .detect or .get_modes might call .adap_enable, which leads to this - * function being called with that mutex held. - * - * Concurrency is not an issue for the moment since we don't share any - * state with KMS, so we can ignore the lock for now, but we need to - * keep it in mind if we were to change that assumption. - */ + mutex_lock(&vc4_hdmi->mutex); spin_lock_irqsave(&vc4_hdmi->hw_lock, flags); @@ -2763,6 +2757,8 @@ static int vc4_hdmi_cec_disable(struct cec_adapter *adap) spin_unlock_irqrestore(&vc4_hdmi->hw_lock, flags); + mutex_unlock(&vc4_hdmi->mutex); + pm_runtime_put(&vc4_hdmi->pdev->dev); drm_dev_exit(idx); @@ -2785,17 +2781,6 @@ static int vc4_hdmi_cec_adap_log_addr(struct cec_adapter *adap, u8 log_addr) unsigned long flags; int idx; - /* - * NOTE: This function should really take vc4_hdmi->mutex, but doing so - * results in a reentrancy since cec_s_phys_addr_from_edid() called in - * .detect or .get_modes might call .adap_enable, which leads to this - * function being called with that mutex held. - * - * Concurrency is not an issue for the moment since we don't share any - * state with KMS, so we can ignore the lock for now, but we need to - * keep it in mind if we were to change that assumption. - */ - if (!drm_dev_enter(drm, &idx)) /* * We can't return an error code, because the CEC @@ -2804,11 +2789,13 @@ static int vc4_hdmi_cec_adap_log_addr(struct cec_adapter *adap, u8 log_addr) */ return 0; + mutex_lock(&vc4_hdmi->mutex); spin_lock_irqsave(&vc4_hdmi->hw_lock, flags); HDMI_WRITE(HDMI_CEC_CNTRL_1, (HDMI_READ(HDMI_CEC_CNTRL_1) & ~VC4_HDMI_CEC_ADDR_MASK) | (log_addr & 0xf) << VC4_HDMI_CEC_ADDR_SHIFT); spin_unlock_irqrestore(&vc4_hdmi->hw_lock, flags); + mutex_unlock(&vc4_hdmi->mutex); drm_dev_exit(idx); @@ -2825,17 +2812,6 @@ static int vc4_hdmi_cec_adap_transmit(struct cec_adapter *adap, u8 attempts, unsigned int i; int idx; - /* - * NOTE: This function should really take vc4_hdmi->mutex, but doing so - * results in a reentrancy since cec_s_phys_addr_from_edid() called in - * .detect or .get_modes might call .adap_enable, which leads to this - * function being called with that mutex held. - * - * Concurrency is not an issue for the moment since we don't share any - * state with KMS, so we can ignore the lock for now, but we need to - * keep it in mind if we were to change that assumption. - */ - if (!drm_dev_enter(dev, &idx)) return -ENODEV; @@ -2845,6 +2821,8 @@ static int vc4_hdmi_cec_adap_transmit(struct cec_adapter *adap, u8 attempts, return -ENOMEM; } + mutex_lock(&vc4_hdmi->mutex); + spin_lock_irqsave(&vc4_hdmi->hw_lock, flags); for (i = 0; i < msg->len; i += 4) @@ -2864,7 +2842,7 @@ static int vc4_hdmi_cec_adap_transmit(struct cec_adapter *adap, u8 attempts, HDMI_WRITE(HDMI_CEC_CNTRL_1, val); spin_unlock_irqrestore(&vc4_hdmi->hw_lock, flags); - + mutex_unlock(&vc4_hdmi->mutex); drm_dev_exit(idx); return 0; diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h index 79495ef79f09..db823efb2563 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.h +++ b/drivers/gpu/drm/vc4/vc4_hdmi.h @@ -195,15 +195,7 @@ struct vc4_hdmi { /** * @mutex: Mutex protecting the driver access across multiple - * frameworks (KMS, ALSA). - * - * NOTE: While supported, CEC has been left out since - * cec_s_phys_addr_from_edid() might call .adap_enable and lead to a - * reentrancy issue between .get_modes (or .detect) and .adap_enable. - * Since we don't share any state between the CEC hooks and KMS', it's - * not a big deal. The only trouble might come from updating the CEC - * clock divider which might be affected by a modeset, but CEC should - * be resilient to that. + * frameworks (KMS, ALSA, CEC). */ struct mutex mutex; -- 2.37.1