From patchwork Thu Aug  3 15:52:08 2017

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Subject: [v3] dma-mapping: skip USB devices when configuring DMA during probe

From: Johan Hovold <johan@kernel.org>

X-Patchwork-Id: 9879371

Message-Id: <20170803155208.22165-1-johan@kernel.org>

To: Christoph Hellwig <hch@lst.de>,

 Marek Szyprowski <m.szyprowski@samsung.com>,

 Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Cc: =?UTF-8?q?Andreas=20F=C3=A4rber?= <afaerber@suse.de>,

 linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,

 Alan Stern <stern@rowland.harvard.edu>, Johan Hovold <johan@kernel.org>,

 stable <stable@vger.kernel.org>, Robin Murphy <robin.murphy@arm.com>,

 Sricharan R <sricharan@codeaurora.org>,

 Stefan Wahren <stefan.wahren@i2se.com>

Date: Thu,  3 Aug 2017 17:52:08 +0200

USB devices use the DMA mask and offset of the controller, which have

already been setup when a device is probed. Note that modifying the

DMA mask of a USB device would change the mask for the controller (and

all devices on the bus) as the mask is literally shared.

Since commit 2bf698671205 ("USB: of: fix root-hub device-tree node

handling"), of_dma_configure() would be called also for root hubs, which

use the device node of the controller. A separate, long-standing bug

that makes of_dma_configure() generate a 30-bit DMA mask from the RPI3's

"dma-ranges" would thus set a broken mask also for the controller. This

in turn prevents USB devices from enumerating when control transfers

fail:

	dwc2 3f980000.usb: Cannot do DMA to address 0x000000003a166a00

Note that the aforementioned DMA-mask bug was benign for the HCD itself

as the dwc2 driver overwrites the mask previously set by

of_dma_configure() for the platform device in its probe callback. The

mask would only later get corrupted when the root-hub child device was

probed.

Fix this, and similar future problems, by adding a flag to struct device

which prevents driver core from calling dma_configure() during probe and

making sure it is set for USB devices.

Fixes: 09515ef5ddad ("of/acpi: Configure dma operations at probe time for platform/amba/pci bus devices")

Cc: stable <stable@vger.kernel.org>	# 4.12

Cc: Robin Murphy <robin.murphy@arm.com>

Cc: Sricharan R <sricharan@codeaurora.org>

Cc: Stefan Wahren <stefan.wahren@i2se.com>

Reported-by: Hans Verkuil <hverkuil@xs4all.nl>

Signed-off-by: Johan Hovold <johan@kernel.org>

---

v3

 - add flag to struct device to prevent DMA configuration during probe instead

   of checking for the USB bus type, which is not available when USB is built

   as a module as noted by Alan

 - drop moderated rpi list from CC

v2

 - amend commit message and point out that the long-standing 30-bit DMA-mask

   bug was benign to the dwc2 HCD itself (Robin)

 - add and use a new dev_is_usb() helper (Robin)

 drivers/base/dma-mapping.c | 6 ++++++

 drivers/usb/core/usb.c     | 1 +

 include/linux/device.h     | 3 +++

 3 files changed, 10 insertions(+)

diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c

index b555ff9dd8fc..f9f703be0ad1 100644

--- a/drivers/base/dma-mapping.c

+++ b/drivers/base/dma-mapping.c

@@ -345,6 +345,9 @@ int dma_configure(struct device *dev)

 	enum dev_dma_attr attr;

 	int ret = 0;

+	if (dev->skip_dma_configure)

+		return 0;

+

 	if (dev_is_pci(dev)) {

 		bridge = pci_get_host_bridge_device(to_pci_dev(dev));

 		dma_dev = bridge;

@@ -369,6 +372,9 @@ int dma_configure(struct device *dev)

 void dma_deconfigure(struct device *dev)

 {

+	if (dev->skip_dma_configure)

+		return;

+

 	of_dma_deconfigure(dev);

 	acpi_dma_deconfigure(dev);

 }

diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c

index 17681d5638ac..2a85d905b539 100644

--- a/drivers/usb/core/usb.c

+++ b/drivers/usb/core/usb.c

@@ -588,6 +588,7 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,

 	 * Note: calling dma_set_mask() on a USB device would set the

 	 * mask for the entire HCD, so don't do that.

 	 */

+	dev->dev.skip_dma_configure = true;

 	dev->dev.dma_mask = bus->sysdev->dma_mask;

 	dev->dev.dma_pfn_offset = bus->sysdev->dma_pfn_offset;

 	set_dev_node(&dev->dev, dev_to_node(bus->sysdev));

diff --git a/include/linux/device.h b/include/linux/device.h

index 723cd54b94da..022cf258068b 100644

--- a/include/linux/device.h

+++ b/include/linux/device.h

@@ -877,6 +877,8 @@ struct dev_links_info {

  * @offline:	Set after successful invocation of bus type's .offline().

  * @of_node_reused: Set if the device-tree node is shared with an ancestor

  *              device.

+ * @skip_dma_configure: Set if driver core should not configure DMA for this

+ *              device during probe.

  *

  * At the lowest level, every device in a Linux system is represented by an

  * instance of struct device. The device structure contains the information

@@ -965,6 +967,7 @@ struct device {

 	bool			offline_disabled:1;

 	bool			offline:1;

 	bool			of_node_reused:1;

+	bool			skip_dma_configure:1;

 };

 static inline struct device *kobj_to_dev(struct kobject *kobj)