linux-kernel - [PATCH v2 2/4] drm/msm: stop supporting no-IOMMU configuration

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Message-Id: <20250903-msm-no-iommu-v2-2-993016250104@oss.qualcomm.com>
Date: Wed, 03 Sep 2025 13:51:50 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Rob Clark <robin.clark@....qualcomm.com>,
        Dmitry Baryshkov <lumag@...nel.org>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Jessica Zhang <jessica.zhang@....qualcomm.com>,
        Sean Paul <sean@...rly.run>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Antonino Maniscalco <antomani103@...il.com>,
        Konrad Dybcio <konradybcio@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/4] drm/msm: stop supporting no-IOMMU configuration

With the switch to GPUVM the msm driver no longer supports the no-IOMMU
configurations (even without the actual GPU). Return an error in case we
face the lack of the IOMMU.

Fixes: 111fdd2198e6 ("drm/msm: drm_gpuvm conversion")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
---
 drivers/gpu/drm/msm/msm_kms.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_kms.c b/drivers/gpu/drm/msm/msm_kms.c
index 56828d218e88a5fa597755c8ea20da781929386c..4c4dcb095c4df97de42d0673aa2842010a249dca 100644
--- a/drivers/gpu/drm/msm/msm_kms.c
+++ b/drivers/gpu/drm/msm/msm_kms.c
@@ -195,14 +195,13 @@ struct drm_gpuvm *msm_kms_init_vm(struct drm_device *dev)
 		iommu_dev = mdp_dev;
 	else
 		iommu_dev = mdss_dev;
-
 	mmu = msm_iommu_disp_new(iommu_dev, 0);
 	if (IS_ERR(mmu))
 		return ERR_CAST(mmu);
 
 	if (!mmu) {
-		drm_info(dev, "no IOMMU, fallback to phys contig buffers for scanout\n");
-		return NULL;
+		drm_info(dev, "no IOMMU, bailing out\n");
+		return ERR_PTR(-ENODEV);
 	}
 
 	vm = msm_gem_vm_create(dev, mmu, "mdp_kms",

-- 
2.47.2