linux-kernel - [PATCH AUTOSEL 4.19 48/73] of/device: Really only set bus DMA mask when appropriate

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Date:   Wed, 14 Nov 2018 17:21:42 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Robin Murphy <robin.murphy@....com>, Rob Herring <robh@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.19 48/73] of/device: Really only set bus DMA mask when appropriate

From: Robin Murphy <robin.murphy@....com>

[ Upstream commit 6778be4e520959659b27a441c06a84c9cb009085 ]

of_dma_configure() was *supposed* to be following the same logic as
acpi_dma_configure() and only setting bus_dma_mask if some range was
specified by the firmware. However, it seems that subtlety got lost in
the process of fitting it into the differently-shaped control flow, and
as a result the force_dma==true case ends up always setting the bus mask
to the 32-bit default, which is not what anyone wants.

Make sure we only touch it if the DT actually said so.

Fixes: 6c2fb2ea7636 ("of/device: Set bus DMA mask as appropriate")
Reported-by: Aaro Koskinen <aaro.koskinen@....fi>
Reported-by: Jean-Philippe Brucker <jean-philippe.brucker@....com>
Tested-by: Aaro Koskinen <aaro.koskinen@....fi>
Tested-by: John Stultz <john.stultz@...aro.org>
Tested-by: Geert Uytterhoeven <geert+renesas@...der.be>
Tested-by: Robert Richter <robert.richter@...ium.com>
Signed-off-by: Robin Murphy <robin.murphy@....com>
Signed-off-by: Rob Herring <robh@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/of/device.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index 5957cd4fa262..40b9051a7fce 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -149,9 +149,11 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
 	 * set by the driver.
 	 */
 	mask = DMA_BIT_MASK(ilog2(dma_addr + size - 1) + 1);
-	dev->bus_dma_mask = mask;
 	dev->coherent_dma_mask &= mask;
 	*dev->dma_mask &= mask;
+	/* ...but only set bus mask if we found valid dma-ranges earlier */
+	if (!ret)
+		dev->bus_dma_mask = mask;
 
 	coherent = of_dma_is_coherent(np);
 	dev_dbg(dev, "device is%sdma coherent\n",
-- 
2.17.1