linux-kernel - [PATCH 1/2] of: device: Allow DMA range map to be set before of_dma_configure

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Message-Id: <20210115175831.1184260-1-paul.kocialkowski@bootlin.com>
Date:   Fri, 15 Jan 2021 18:58:30 +0100
From:   Paul Kocialkowski <paul.kocialkowski@...tlin.com>
To:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Cc:     Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Subject: [PATCH 1/2] of: device: Allow DMA range map to be set before of_dma_configure_id

A mechanism was recently introduced for the sunxi architecture where
the DMA offset for specific devices (under the MBUS) is set by a common
driver (sunxi_mbus). This driver calls dma_direct_set_offset to set
the device's dma_range_map manually.

However this information was overwritten by of_dma_configure_id, which
obtains the map from of_dma_get_range (or keeps it NULL when it fails
and the force_dma argument is true, which is the case for platform
devices).

As a result, the dma_range_map was always overwritten and the mechanism
could not correctly take effect.

This adds a check to ensure that no previous DMA range map is
overwritten and prints a warning when the map was already set while
also being available from dt. In this case, the map that was already
set is kept.

Fixes: b4bdc4fbf8d0 ("soc: sunxi: Deal with the MBUS DMA offsets in a central place")
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
---
 drivers/of/device.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index aedfaaafd3e7..db1b8634c2c7 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -181,7 +181,14 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,

 	arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);

-	dev->dma_range_map = map;
+	if (!dev->dma_range_map) {
+		dev->dma_range_map = map;
+	} else if (map) {
+		dev_warn(dev,
+			 "DMA range map was already set, ignoring range map from dt\n");
+		kfree(map);
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(of_dma_configure_id);
-- 
2.30.0