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 4F669FCC9B2 for ; Tue, 10 Mar 2026 03:25:57 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 9D7D310E633; Tue, 10 Mar 2026 03:25:56 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=chromium.org header.i=@chromium.org header.b="LfXD2rE4"; dkim-atps=neutral Received: from mail-pl1-f174.google.com (mail-pl1-f174.google.com [209.85.214.174]) by gabe.freedesktop.org (Postfix) with ESMTPS id A96B710E633 for ; Tue, 10 Mar 2026 03:25:55 +0000 (UTC) Received: by mail-pl1-f174.google.com with SMTP id d9443c01a7336-2aaed195901so56661835ad.0 for ; Mon, 09 Mar 2026 20:25:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1773113155; x=1773717955; darn=lists.freedesktop.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Y1z9EtizHwE3LeSySxAXfxT/FNlt1Ydhsh1vDf6WdY0=; b=LfXD2rE4m7ToGk549n3g3KpEADVUD95kf4Z6OoAYE8Q/krITatObigJnkisHaH+UEn owgnK/K5/P5r8vZX5fJYBrwjXDVS2qIEzLS8TatwCJzdJeLkgmkS6PXQocBNP4NC0Xuj H4VoVCFVREINQZrqO1fY8k39GWcTCPuJP9pOw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1773113155; x=1773717955; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=Y1z9EtizHwE3LeSySxAXfxT/FNlt1Ydhsh1vDf6WdY0=; b=ArWHwsB2lojzXwW7KrNeWTNzN+C8pPG3yEcbfjBxyedcqle1GUsKoxp17pkAYd0OiG YfYP5hDOesGMA5LZbD+Vg9Npfy6Yu5gFXR4UND04RIwjoiy4Eu8wAF5/0n8XTXu22Lty 8L/bPe/v1pzN/R/CbsJX2BBV9y53OXOWj/HyW4M9fEHqwV/oLTTRYAManwVVn+Ke9pJx x4FC12m8B7I/rmYqyePRHVS9KQP5xl9lf80RD9C1b7LZpE8BTtZ/Rjkd9H7Ez8FPaA8w v4wlCN6nNSXedvzRbMngMhJEt6onOt1Jotz1Us8DWlyzAstMw33vE/7Akd1K+j+nFs9o REmQ== X-Forwarded-Encrypted: i=1; AJvYcCXOb5QzGdpqxmYZWx8UAKDyAIAf1x0vppClLLsCP64OsAipqGjyVIS75sy2HUh5ycXAgAD6mZl+YAM=@lists.freedesktop.org X-Gm-Message-State: AOJu0YyJwSVuJn8MsOex6xc20NzbC/l8e1awwN38xKNkq0Tlwv8nXeb0 xPdedAMJsKHgHqyic6dpc2E7oOFzU9XiAKnq1vF401CmxF27bdiTyUeDG8N7SluZcg== X-Gm-Gg: ATEYQzyDmyOOIgv2eZ+/eOdAGV4yF1R9pd8nXv9lONIbWxST4NJilA9CrUJJFJ9uumn 94GuZ/mf3UgtPO8n8JYWbLdn73cfDJbYr9KINxJIHTOJ2xQPGtUJB54pzIdhYyWy9Dv1MztXX6B onDEvmu19WxMYRKF0jJ37KgtsQ7TsBWmG0kH50dRlCzCqxzbS03g6y16f6uShl/PNuGuGhn9cIq y/IomrJtqCQx8lHXkNUt+SyiI36KC9qO3GX/pM3pjj127GWeaMqaHtJ6Pqz8YZoLKdigAggo7HG lcOENG1QZ9SatisIuEtXZciVtKgpZpyp15hdJZdcglA85rDhQcdj7eemMWBrehNbomDAiTiAx7Q KS1rGEXsLCYQrUT6y9mJKy1SbCbHYVNAx62BN9DZ5XtU+aSRL6mZQhOvoXTLurgoXRvCxzskqKY AjaChhyS3rOutcl398HFi45Pf5sN09df7f0n7mrQTVODkilHTRcyjSo/NQf12eoa7D/B+A96dDN aip7J3e X-Received: by 2002:a17:902:ec88:b0:2ae:54b2:27c7 with SMTP id d9443c01a7336-2ae82459ca5mr139254635ad.39.1773113155156; Mon, 09 Mar 2026 20:25:55 -0700 (PDT) Received: from wenstp920.tpe.corp.google.com ([2a00:79e0:201d:8:ee38:e01e:e888:6900]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2ae83e575e6sm126695095ad.5.2026.03.09.20.25.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Mar 2026 20:25:54 -0700 (PDT) From: Chen-Yu Tsai To: Matthias Brugger , AngeloGioacchino Del Regno , Chun-Kuang Hu , Philipp Zabel , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , David Airlie , Simona Vetter Cc: Chen-Yu Tsai , linux-sunxi@lists.linux.dev, Paul Kocialkowski , linux-mediatek@lists.infradead.org, dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH RESEND 4/4] drm/sun4i: Use backend/mixer as dedicated DMA device Date: Tue, 10 Mar 2026 11:25:09 +0800 Message-ID: <20260310032511.2545500-5-wenst@chromium.org> X-Mailer: git-send-email 2.53.0.473.g4a7958ca14-goog In-Reply-To: <20260310032511.2545500-1-wenst@chromium.org> References: <20260310032511.2545500-1-wenst@chromium.org> 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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" The sun4i DRM driver deals with DMA constraints in a peculiar way. Instead of using the actual DMA device in various helpers, it justs reconfigures the DMA constraints of the virtual display device using the DMA device's device tree node by calling of_dma_configure(). Turns out of_dma_configure() should only be called from bus code. Lately this also triggers a big warning through of_iommu_configure() and ultimately __iommu_probe_device(): late IOMMU probe at driver bind, something fishy here! Now that the GEM DMA helpers have proper support for allocating and mapping buffers with a dedicated DMA device, switch over to it as the proper solution. The mixer change was tested on a Pine H64 model B. The backend change was only compile tested. Though I don't expect any issues, help testing on an older device would be appreciated. Signed-off-by: Chen-Yu Tsai --- drivers/gpu/drm/sun4i/sun4i_backend.c | 27 +++++++++++++++------------ drivers/gpu/drm/sun4i/sun8i_mixer.c | 27 +++++++++++++++------------ 2 files changed, 30 insertions(+), 24 deletions(-) diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c b/drivers/gpu/drm/sun4i/sun4i_backend.c index 6391bdc94a5c..a57fb5151def 100644 --- a/drivers/gpu/drm/sun4i/sun4i_backend.c +++ b/drivers/gpu/drm/sun4i/sun4i_backend.c @@ -798,18 +798,21 @@ static int sun4i_backend_bind(struct device *dev, struct device *master, dev_set_drvdata(dev, backend); spin_lock_init(&backend->frontend_lock); - if (of_property_present(dev->of_node, "interconnects")) { - /* - * This assume we have the same DMA constraints for all our the - * devices in our pipeline (all the backends, but also the - * frontends). This sounds bad, but it has always been the case - * for us, and DRM doesn't do per-device allocation either, so - * we would need to fix DRM first... - */ - ret = of_dma_configure(drm->dev, dev->of_node, true); - if (ret) - return ret; - } + /* + * This assume we have the same DMA constraints for all our the + * devices in our pipeline (all the backends, but also the + * frontends). This sounds bad, but it has always been the case + * for us, and DRM doesn't do per-device allocation either, so + * we would need to fix DRM first... + * + * Always use the first bound backend as the DMA device. While + * our device trees always have all backends enabled, some in + * the wild may actually have the first one disabled. If both + * are enabled, the order in which they are bound is guaranteed + * since the driver adds components in order. + */ + if (drm_dev_dma_dev(drm) == drm->dev) + drm_dev_set_dma_dev(drm, dev); backend->engine.node = dev->of_node; backend->engine.ops = &sun4i_backend_engine_ops; diff --git a/drivers/gpu/drm/sun4i/sun8i_mixer.c b/drivers/gpu/drm/sun4i/sun8i_mixer.c index 02acc7cbdb97..4071ab38b4ae 100644 --- a/drivers/gpu/drm/sun4i/sun8i_mixer.c +++ b/drivers/gpu/drm/sun4i/sun8i_mixer.c @@ -536,18 +536,21 @@ static int sun8i_mixer_bind(struct device *dev, struct device *master, mixer->engine.ops = &sun8i_engine_ops; mixer->engine.node = dev->of_node; - if (of_property_present(dev->of_node, "iommus")) { - /* - * This assume we have the same DMA constraints for - * all our the mixers in our pipeline. This sounds - * bad, but it has always been the case for us, and - * DRM doesn't do per-device allocation either, so we - * would need to fix DRM first... - */ - ret = of_dma_configure(drm->dev, dev->of_node, true); - if (ret) - return ret; - } + /* + * This assume we have the same DMA constraints for all our the + * devices in our pipeline (all the backends, but also the + * frontends). This sounds bad, but it has always been the case + * for us, and DRM doesn't do per-device allocation either, so + * we would need to fix DRM first... + * + * Always use the first bound backend as the DMA device. While + * our device trees always have all backends enabled, some in + * the wild may actually have the first one disabled. If both + * are enabled, the order in which they are bound is guaranteed + * since the driver adds components in order. + */ + if (drm_dev_dma_dev(drm) == drm->dev) + drm_dev_set_dma_dev(drm, dev); /* * While this function can fail, we shouldn't do anything -- 2.53.0.473.g4a7958ca14-goog