@@ -195,6 +195,7 @@ struct bus_type amba_bustype = {
.match = amba_match,
.uevent = amba_uevent,
.pm = &amba_pm,
+ .force_dma = true,
};
static int __init amba_init(void)
@@ -1142,6 +1142,7 @@ struct bus_type platform_bus_type = {
.match = platform_match,
.uevent = platform_uevent,
.pm = &platform_dev_pm_ops,
+ .force_dma = true,
};
EXPORT_SYMBOL_GPL(platform_bus_type);
@@ -320,6 +320,7 @@ struct bus_type host1x_bus_type = {
.name = "host1x",
.match = host1x_device_match,
.pm = &host1x_device_pm_ops,
+ .force_dma = true,
};
static void __host1x_device_del(struct host1x_device *device)
@@ -9,9 +9,7 @@
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/slab.h>
-#include <linux/pci.h>
#include <linux/platform_device.h>
-#include <linux/amba/bus.h>
#include <asm/errno.h>
#include "of_private.h"
@@ -101,11 +99,7 @@ int of_dma_configure(struct device *dev, struct device_node *np)
* DMA configuration regardless of whether "dma-ranges" is
* correctly specified or not.
*/
- if (!dev_is_pci(dev) &&
-#ifdef CONFIG_ARM_AMBA
- dev->bus != &amba_bustype &&
-#endif
- dev->bus != &platform_bus_type)
+ if (!dev->bus->force_dma)
return ret == -ENODEV ? 0 : ret;
dma_addr = offset = 0;
@@ -1466,6 +1466,7 @@ struct bus_type pci_bus_type = {
.drv_groups = pci_drv_groups,
.pm = PCI_PM_OPS_PTR,
.num_vf = pci_bus_num_vf,
+ .force_dma = true,
};
EXPORT_SYMBOL(pci_bus_type);
@@ -97,6 +97,8 @@ extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
* @p: The private data of the driver core, only the driver core can
* touch this.
* @lock_key: Lock class key for use by the lock validator
+ * @force_dma: Assume devices on this bus should be set up by dma_configure()
+ * even if DMA capability is not explicitly described by firmware.
*
* A bus is a channel between the processor and one or more devices. For the
* purposes of the device model, all devices are connected via a bus, even if
@@ -135,6 +137,8 @@ struct bus_type {
struct subsys_private *p;
struct lock_class_key lock_key;
+
+ bool force_dma;
};
extern int __must_check bus_register(struct bus_type *bus);
We do not want the common dma_configure() pathway to apply indiscriminately to all devices, since there are plenty of buses which do not have DMA capability, and if their child devices were used for DMA API calls it would only be indicative of a driver bug. However, there are a number of buses for which DMA is implicitly expected even when not described by firmware - those we whitelist with an automatic opt-in to dma_configure(), assuming that the DMA address space and the physical address space are equivalent if not otherwise specified. Commit 723288836628 ("of: restrict DMA configuration") introduced a short-term fix by comparing explicit bus types, but this approach is far from pretty, doesn't scale well, and fails to cope at all with bus drivers which may be built as modules, like host1x. Let's refine things by making that opt-in a property of the bus type, which neatly addresses those problems and lets the decision of whether firmware description of DMA capability should be optional or mandatory stay internal to the bus drivers themselves. Acked-by: Thierry Reding <treding@nvidia.com> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- I've not included the pci_epf change here as it's dubious whether that's doing the right thing to begin with. Robin. drivers/amba/bus.c | 1 + drivers/base/platform.c | 1 + drivers/gpu/host1x/bus.c | 1 + drivers/of/device.c | 8 +------- drivers/pci/pci-driver.c | 1 + include/linux/device.h | 4 ++++ 6 files changed, 9 insertions(+), 7 deletions(-)