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 E831B1049521 for ; Wed, 11 Mar 2026 09:50:12 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 51E8C10E3D0; Wed, 11 Mar 2026 09:50:12 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=chromium.org header.i=@chromium.org header.b="XdhuDAEq"; dkim-atps=neutral Received: from mail-pf1-f182.google.com (mail-pf1-f182.google.com [209.85.210.182]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8F47D10E3D0 for ; Wed, 11 Mar 2026 09:50:10 +0000 (UTC) Received: by mail-pf1-f182.google.com with SMTP id d2e1a72fcca58-8298fad2063so3524353b3a.3 for ; Wed, 11 Mar 2026 02:50:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1773222610; x=1773827410; 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=XdhuDAEqhVHWbWeSMYusMUVZc3VcSSHzQ5ltFnN+slj96IQ2WNGjmJnGJWzgn+VI7R xf6ZNlzONn6EkPDRFlIK6d6ixQtTUhxxhHjZxVtdlooTKurhsmJgTrEoFGWGjiTrP8ks icRDKz16yx0KVzTsIYIFRuo9A1GSEvuU9V+xA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1773222610; x=1773827410; 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=F1ciiqezrPO2SeW2Wt0hmU3fKzvWdDdoeKmBnaurc6NGfnPqPDpkMaMm1DZSt6+LCI 12t0bSZZFVkZ0L27Nhdz+Vt4rV5Tpwfw0ENoKXoMPJbJx/KKTa/B2pqOPcr8ScA0OYR0 z6pBJBGa+WnBFxctZJlQ2HtMCJy5MQ/tePcC4Xf6Cv5VKL4OzUq3mxz0dSSd8nTxTrhy m5qSrb53ImJAte6jHDfyCDh+0GryUP1Ang8TyCIFNjXP5Koyhkb7jedrIxJ49QgkNffv lk7/uL69WFzQ/Cyu5nv/ptLm/KlNu9cxyWKiTgYrPXYdRc1vIN8hlEjQrInk4ZaZRaXQ CaCw== X-Forwarded-Encrypted: i=1; AJvYcCV3aGO4+0b2eji/Aa1bt1ovdBKfK9B9N6+G4jcw4H0efsmis8U6gOil9OXECoZBGPVjLNaFhLp/gdc=@lists.freedesktop.org X-Gm-Message-State: AOJu0YwFHyJCNzZyv/fC/SN+Ul8gwqCma31aFT+FPSL90t/0VBSEvgWf G4MEdEWiMy2NZ8o6pypM1rLHdD7hHEDpiAgPESI8+UfarW0jwXSMg+QVrxfIxoLndw== X-Gm-Gg: ATEYQzzQTWWg0MJ2zZxgp18SGWBwpeFI4xax10O0K8Za1RrLUyk3tgGfyfjMyBYEgXj Fi1UmTJVfz4gH10yYjEpdUmn/yfvy1codH0XZtmNvOGMBZdCxDMiUBpRIDUqt37d+m1jKTq06Yk Qwyeuj7FqjDJbFb16+glLB6ITb1PUXkbWifKF4BDDHBH0hCJtlwB2EFPoDxMkQQD/4bZiYuVHyc Czq1KIscLcIT6kc5HX/pOseHyeot4kE5IdVBUdkRB+a0v4SsXcfbFXbuvwUTAyB//3mvCZspFJN zn9gb303fCoWxnbzgkV+AFP5bdxn19zcTScZvUiQGYAc8fM90UV4kyzzSj6OUBgh12ybOUCpxdl ihhmbx7/67/o/lLG9YnAWnEXYuRwiFJBzElXxQwD2eipNxSjakzCsH44+T5gWi9+PewsQoNiWku QxK3314MJXy9r4qVG/U6/gOXgS4fWfY3K+DOP+nrzePxy3g2+jl8ENfiUO7vyKfFBD4+vavd99u qszcXkX X-Received: by 2002:a05:6a00:950c:b0:829:6f28:1d6 with SMTP id d2e1a72fcca58-829f6e7b408mr1826676b3a.13.1773222610050; Wed, 11 Mar 2026 02:50:10 -0700 (PDT) Received: from wenstp920.tpe.corp.google.com ([2a00:79e0:201d:8:805b:14e9:f783:bcae]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-829f6e22f85sm1887598b3a.27.2026.03.11.02.50.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Mar 2026 02:50:09 -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 v2 4/4] drm/sun4i: Use backend/mixer as dedicated DMA device Date: Wed, 11 Mar 2026 17:49:28 +0800 Message-ID: <20260311094929.3393338-5-wenst@chromium.org> X-Mailer: git-send-email 2.53.0.473.g4a7958ca14-goog In-Reply-To: <20260311094929.3393338-1-wenst@chromium.org> References: <20260311094929.3393338-1-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