From d5185965c3b59073c4520bad7dd2adf725b9abba Mon Sep 17 00:00:00 2001
From: Dmitry Osipenko <digetx@gmail.com>
Date: Sat, 4 Dec 2021 17:58:48 +0300
Subject: [PATCH] gpu: host1x: Add back arm_iommu_detach_device()
Git-commit: d5185965c3b59073c4520bad7dd2adf725b9abba
Patch-mainline: v5.17-rc1
References: git-fixes

Host1x DMA buffer isn't mapped properly when CONFIG_ARM_DMA_USE_IOMMU=y.
The memory management code of Host1x driver has a longstanding overhaul
overdue and it's not obvious where the problem is in this case. Hence
let's add back the old workaround which we already had sometime before.
It explicitly detaches Host1x device from the offending implicit IOMMU
domain. This fixes a completely broken Host1x DMA in case of ARM32
multiplatform kernel config.

Cc: stable@vger.kernel.org
Fixes: af1cbfb9bf0f ("gpu: host1x: Support DMA mapping of buffers")
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/host1x/dev.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
index 14c1ea7506fb..6994f8c0e02e 100644
--- a/drivers/gpu/host1x/dev.c
+++ b/drivers/gpu/host1x/dev.c
@@ -22,6 +22,10 @@
 #include <trace/events/host1x.h>
 #undef CREATE_TRACE_POINTS
 
+#if IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)
+#include <asm/dma-iommu.h>
+#endif
+
 #include "bus.h"
 #include "channel.h"
 #include "debug.h"
@@ -263,6 +267,17 @@ static struct iommu_domain *host1x_iommu_attach(struct host1x *host)
 	struct iommu_domain *domain = iommu_get_domain_for_dev(host->dev);
 	int err;
 
+#if IS_ENABLED(CONFIG_ARM_DMA_USE_IOMMU)
+	if (host->dev->archdata.mapping) {
+		struct dma_iommu_mapping *mapping =
+				to_dma_iommu_mapping(host->dev);
+		arm_iommu_detach_device(host->dev);
+		arm_iommu_release_mapping(mapping);
+
+		domain = iommu_get_domain_for_dev(host->dev);
+	}
+#endif
+
 	/*
 	 * We may not always want to enable IOMMU support (for example if the
 	 * host1x firewall is already enabled and we don't support addressing
-- 
2.31.1