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 simply skipping USB devices
when dma_configure() is called during probe.
Fixes: 09515ef5ddad ("of/acpi: Configure dma operations at probe time for platform/amba/pci bus devices")
Cc: stable <stable@xxxxxxxxxxxxxxx> # 4.12
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Sricharan R <sricharan@xxxxxxxxxxxxxx>
Cc: Stefan Wahren <stefan.wahren@xxxxxxxx>
Reported-by: Hans Verkuil <hverkuil@xxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
---
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 | 8 ++++++++
include/linux/usb.h | 5 +++++
2 files changed, 13 insertions(+)
diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
index b555ff9dd8fc..604e99e6660a 100644
--- a/drivers/base/dma-mapping.c
+++ b/drivers/base/dma-mapping.c
@@ -13,6 +13,7 @@
#include <linux/gfp.h>
#include <linux/of_device.h>
#include <linux/slab.h>
+#include <linux/usb.h>
#include <linux/vmalloc.h>
/*
@@ -345,6 +346,10 @@ int dma_configure(struct device *dev)
enum dev_dma_attr attr;
int ret = 0;
+ /* USB devices share the controller's mask. */
+ if (dev_is_usb(dev))
+ return 0;
+
if (dev_is_pci(dev)) {
bridge = pci_get_host_bridge_device(to_pci_dev(dev));
dma_dev = bridge;
@@ -369,6 +374,9 @@ int dma_configure(struct device *dev)
void dma_deconfigure(struct device *dev)
{
+ if (dev_is_usb(dev))
+ return;
+
of_dma_deconfigure(dev);
acpi_dma_deconfigure(dev);
}
diff --git a/include/linux/usb.h b/include/linux/usb.h
index cb9fbd54386e..f86ad9d8c756 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1222,6 +1222,11 @@ struct usb_device_driver {
extern struct bus_type usb_bus_type;
+static inline bool dev_is_usb(struct device *dev)
+{
+ return dev->bus == &usb_bus_type;
+}
+
/**
* struct usb_class_driver - identifies a USB driver that wants to use the USB major number
* @name: the usb class device name for this driver. Will show up in sysfs.
--
2.13.3