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@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> --- 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) -- 2.13.3