Merge tag 'dma-mapping-4.18' of git://git.infradead.org/users/hch/dma-mapping

Pull dma-mapping updates from Christoph Hellwig:

 - replace the force_dma flag with a dma_configure bus method. (Nipun
   Gupta, although one patch is іncorrectly attributed to me due to a
   git rebase bug)

 - use GFP_DMA32 more agressively in dma-direct. (Takashi Iwai)

 - remove PCI_DMA_BUS_IS_PHYS and rely on the dma-mapping API to do the
   right thing for bounce buffering.

 - move dma-debug initialization to common code, and apply a few
   cleanups to the dma-debug code.

 - cleanup the Kconfig mess around swiotlb selection

 - swiotlb comment fixup (Yisheng Xie)

 - a trivial swiotlb fix. (Dan Carpenter)

 - support swiotlb on RISC-V. (based on a patch from Palmer Dabbelt)

 - add a new generic dma-noncoherent dma_map_ops implementation and use
   it for arc, c6x and nds32.

 - improve scatterlist validity checking in dma-debug. (Robin Murphy)

 - add a struct device quirk to limit the dma-mask to 32-bit due to
   bridge/system issues, and switch x86 to use it instead of a local
   hack for VIA bridges.

 - handle devices without a dma_mask more gracefully in the dma-direct
   code.

* tag 'dma-mapping-4.18' of git://git.infradead.org/users/hch/dma-mapping: (48 commits)
  dma-direct: don't crash on device without dma_mask
  nds32: use generic dma_noncoherent_ops
  nds32: implement the unmap_sg DMA operation
  nds32: consolidate DMA cache maintainance routines
  x86/pci-dma: switch the VIA 32-bit DMA quirk to use the struct device flag
  x86/pci-dma: remove the explicit nodac and allowdac option
  x86/pci-dma: remove the experimental forcesac boot option
  Documentation/x86: remove a stray reference to pci-nommu.c
  core, dma-direct: add a flag 32-bit dma limits
  dma-mapping: remove unused gfp_t parameter to arch_dma_alloc_attrs
  dma-debug: check scatterlist segments
  c6x: use generic dma_noncoherent_ops
  arc: use generic dma_noncoherent_ops
  arc: fix arc_dma_{map,unmap}_page
  arc: fix arc_dma_sync_sg_for_{cpu,device}
  arc: simplify arc_dma_sync_single_for_{cpu,device}
  dma-mapping: provide a generic dma-noncoherent implementation
  dma-mapping: simplify Kconfig dependencies
  riscv: add swiotlb support
  riscv: only enable ZONE_DMA32 for 64-bit
  ...

21 files changed, 81 insertions, 113 deletions

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 4a3ac31c07d0..3b0118786b43 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -20,6 +20,7 @@
 #include <linux/sizes.h>
 #include <linux/limits.h>
 #include <linux/clk/clk-conf.h>
+#include <linux/platform_device.h>
 
 #include <asm/irq.h>
 
@@ -193,14 +194,16 @@ static const struct dev_pm_ops amba_pm = {
 /*
  * Primecells are part of the Advanced Microcontroller Bus Architecture,
  * so we call the bus "amba".
+ * DMA configuration for platform and AMBA bus is same. So here we reuse
+ * platform's DMA config routine.
  */
 struct bus_type amba_bustype = {
 	.name		= "amba",
 	.dev_groups	= amba_dev_groups,
 	.match		= amba_match,
 	.uevent		= amba_uevent,
+	.dma_configure	= platform_dma_configure,
 	.pm		= &amba_pm,
-	.force_dma	= true,
 };
 
 static int __init amba_init(void)
diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
index d82566d6e237..f831a582209c 100644
--- a/drivers/base/dma-mapping.c
+++ b/drivers/base/dma-mapping.c
@@ -329,36 +329,13 @@ void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags)
 #endif
 
 /*
- * Common configuration to enable DMA API use for a device
+ * enables DMA API use for a device
  */
-#include <linux/pci.h>
-
 int dma_configure(struct device *dev)
 {
-	struct device *bridge = NULL, *dma_dev = dev;
-	enum dev_dma_attr attr;
-	int ret = 0;
-
-	if (dev_is_pci(dev)) {
-		bridge = pci_get_host_bridge_device(to_pci_dev(dev));
-		dma_dev = bridge;
-		if (IS_ENABLED(CONFIG_OF) && dma_dev->parent &&
-		    dma_dev->parent->of_node)
-			dma_dev = dma_dev->parent;
-	}
-
-	if (dma_dev->of_node) {
-		ret = of_dma_configure(dev, dma_dev->of_node);
-	} else if (has_acpi_companion(dma_dev)) {
-		attr = acpi_get_dma_attr(to_acpi_device_node(dma_dev->fwnode));
-		if (attr != DEV_DMA_NOT_SUPPORTED)
-			ret = acpi_dma_configure(dev, attr);
-	}
-
-	if (bridge)
-		pci_put_host_bridge_device(bridge);
-
-	return ret;
+	if (dev->bus->dma_configure)
+		return dev->bus->dma_configure(dev);
+	return 0;
 }
 
 void dma_deconfigure(struct device *dev)
diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 8075ddc70a17..c0ff1e73a634 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -1130,6 +1130,22 @@ int platform_pm_restore(struct device *dev)
 
 #endif /* CONFIG_HIBERNATE_CALLBACKS */
 
+int platform_dma_configure(struct device *dev)
+{
+	enum dev_dma_attr attr;
+	int ret = 0;
+
+	if (dev->of_node) {
+		ret = of_dma_configure(dev, dev->of_node, true);
+	} else if (has_acpi_companion(dev)) {
+		attr = acpi_get_dma_attr(to_acpi_device_node(dev->fwnode));
+		if (attr != DEV_DMA_NOT_SUPPORTED)
+			ret = acpi_dma_configure(dev, attr);
+	}
+
+	return ret;
+}
+
 static const struct dev_pm_ops platform_dev_pm_ops = {
 	.runtime_suspend = pm_generic_runtime_suspend,
 	.runtime_resume = pm_generic_runtime_resume,
@@ -1141,8 +1157,8 @@ struct bus_type platform_bus_type = {
 	.dev_groups	= platform_dev_groups,
 	.match		= platform_match,
 	.uevent		= platform_uevent,
+	.dma_configure	= platform_dma_configure,
 	.pm		= &platform_dev_pm_ops,
-	.force_dma	= true,
 };
 EXPORT_SYMBOL_GPL(platform_bus_type);
 
diff --git a/drivers/bcma/main.c b/drivers/bcma/main.c
index e6986c7608f1..fc1f4acdd189 100644
--- a/drivers/bcma/main.c
+++ b/drivers/bcma/main.c
@@ -207,7 +207,7 @@ static void bcma_of_fill_device(struct device *parent,
 
 	core->irq = bcma_of_get_irq(parent, core, 0);
 
-	of_dma_configure(&core->dev, node);
+	of_dma_configure(&core->dev, node, false);
 }
 
 unsigned int bcma_core_irq(struct bcma_device *core, int num)
diff --git a/drivers/dma/qcom/hidma_mgmt.c b/drivers/dma/qcom/hidma_mgmt.c
index 000c7019ca7d..d64edeb6771a 100644
--- a/drivers/dma/qcom/hidma_mgmt.c
+++ b/drivers/dma/qcom/hidma_mgmt.c
@@ -398,7 +398,7 @@ static int __init hidma_mgmt_of_populate_channels(struct device_node *np)
 		}
 		of_node_get(child);
 		new_pdev->dev.of_node = child;
-		of_dma_configure(&new_pdev->dev, child);
+		of_dma_configure(&new_pdev->dev, child, true);
 		/*
 		 * It is assumed that calling of_msi_configure is safe on
 		 * platforms with or without MSI support.
diff --git a/drivers/gpu/host1x/bus.c b/drivers/gpu/host1x/bus.c
index 88a3558b7916..815bdb42e3f0 100644
--- a/drivers/gpu/host1x/bus.c
+++ b/drivers/gpu/host1x/bus.c
@@ -314,6 +314,11 @@ static int host1x_device_match(struct device *dev, struct device_driver *drv)
 	return strcmp(dev_name(dev), drv->name) == 0;
 }
 
+static int host1x_dma_configure(struct device *dev)
+{
+	return of_dma_configure(dev, dev->of_node, true);
+}
+
 static const struct dev_pm_ops host1x_device_pm_ops = {
 	.suspend = pm_generic_suspend,
 	.resume = pm_generic_resume,
@@ -326,8 +331,8 @@ static const struct dev_pm_ops host1x_device_pm_ops = {
 struct bus_type host1x_bus_type = {
 	.name = "host1x",
 	.match = host1x_device_match,
+	.dma_configure	= host1x_dma_configure,
 	.pm = &host1x_device_pm_ops,
-	.force_dma = true,
 };
 
 static void __host1x_device_del(struct host1x_device *device)
@@ -416,7 +421,7 @@ static int host1x_device_add(struct host1x *host1x,
 	device->dev.bus = &host1x_bus_type;
 	device->dev.parent = host1x->dev;
 
-	of_dma_configure(&device->dev, host1x->dev->of_node);
+	of_dma_configure(&device->dev, host1x->dev->of_node, true);
 
 	err = host1x_device_parse_dt(device, driver);
 	if (err < 0) {
diff --git a/drivers/ide/ide-dma.c b/drivers/ide/ide-dma.c
index 54d4d78ca46a..6f344654ef22 100644
--- a/drivers/ide/ide-dma.c
+++ b/drivers/ide/ide-dma.c
@@ -180,7 +180,6 @@ EXPORT_SYMBOL_GPL(ide_dma_unmap_sg);
 void ide_dma_off_quietly(ide_drive_t *drive)
 {
 	drive->dev_flags &= ~IDE_DFLAG_USING_DMA;
-	ide_toggle_bounce(drive, 0);
 
 	drive->hwif->dma_ops->dma_host_set(drive, 0);
 }
@@ -211,7 +210,6 @@ EXPORT_SYMBOL(ide_dma_off);
 void ide_dma_on(ide_drive_t *drive)
 {
 	drive->dev_flags |= IDE_DFLAG_USING_DMA;
-	ide_toggle_bounce(drive, 1);
 
 	drive->hwif->dma_ops->dma_host_set(drive, 1);
 }
diff --git a/drivers/ide/ide-lib.c b/drivers/ide/ide-lib.c
index e1180fa46196..78cb79eddc8b 100644
--- a/drivers/ide/ide-lib.c
+++ b/drivers/ide/ide-lib.c
@@ -6,32 +6,6 @@
 #include <linux/ide.h>
 #include <linux/bitops.h>
 
-/**
- *	ide_toggle_bounce	-	handle bounce buffering
- *	@drive: drive to update
- *	@on: on/off boolean
- *
- *	Enable or disable bounce buffering for the device. Drives move
- *	between PIO and DMA and that changes the rules we need.
- */
-
-void ide_toggle_bounce(ide_drive_t *drive, int on)
-{
-	u64 addr = BLK_BOUNCE_HIGH;	/* dma64_addr_t */
-
-	if (!PCI_DMA_BUS_IS_PHYS) {
-		addr = BLK_BOUNCE_ANY;
-	} else if (on && drive->media == ide_disk) {
-		struct device *dev = drive->hwif->dev;
-
-		if (dev && dev->dma_mask)
-			addr = *dev->dma_mask;
-	}
-
-	if (drive->queue)
-		blk_queue_bounce_limit(drive->queue, addr);
-}
-
 u64 ide_get_lba_addr(struct ide_cmd *cmd, int lba48)
 {
 	struct ide_taskfile *tf = &cmd->tf;
diff --git a/drivers/ide/ide-probe.c b/drivers/ide/ide-probe.c
index 2019e66eada7..56d7bc228cb3 100644
--- a/drivers/ide/ide-probe.c
+++ b/drivers/ide/ide-probe.c
@@ -796,8 +796,7 @@ static int ide_init_queue(ide_drive_t *drive)
 	 * This will be fixed once we teach pci_map_sg() about our boundary
 	 * requirements, hopefully soon. *FIXME*
 	 */
-	if (!PCI_DMA_BUS_IS_PHYS)
-		max_sg_entries >>= 1;
+	max_sg_entries >>= 1;
 #endif /* CONFIG_PCI */
 
 	blk_queue_max_segments(q, max_sg_entries);
@@ -805,9 +804,6 @@ static int ide_init_queue(ide_drive_t *drive)
 	/* assign drive queue */
 	drive->queue = q;
 
-	/* needs drive->queue to be set */
-	ide_toggle_bounce(drive, 1);
-
 	return 0;
 }
 
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index df171cb85822..5b714a062fa7 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -146,6 +146,7 @@ config INTEL_IOMMU
 	select DMA_DIRECT_OPS
 	select IOMMU_API
 	select IOMMU_IOVA
+	select NEED_DMA_MAP_STATE
 	select DMAR_TABLE
 	help
 	  DMA remapping (DMAR) devices support enables independent address
diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index a4ebd8715494..661828e8fdcf 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -1289,9 +1289,8 @@ static int efx_init_io(struct efx_nic *efx)
 
 	pci_set_master(pci_dev);
 
-	/* Set the PCI DMA mask.  Try all possibilities from our
-	 * genuine mask down to 32 bits, because some architectures
-	 * (e.g. x86_64 with iommu_sac_force set) will allow 40 bit
+	/* Set the PCI DMA mask.  Try all possibilities from our genuine mask
+	 * down to 32 bits, because some architectures will allow 40 bit
 	 * masks event though they reject 46 bit masks.
 	 */
 	while (dma_mask > 0x7fffffffUL) {
diff --git a/drivers/net/ethernet/sfc/falcon/efx.c b/drivers/net/ethernet/sfc/falcon/efx.c
index 3d6c91e96589..dd5530a4f8c8 100644
--- a/drivers/net/ethernet/sfc/falcon/efx.c
+++ b/drivers/net/ethernet/sfc/falcon/efx.c
@@ -1242,9 +1242,8 @@ static int ef4_init_io(struct ef4_nic *efx)
 
 	pci_set_master(pci_dev);
 
-	/* Set the PCI DMA mask.  Try all possibilities from our
-	 * genuine mask down to 32 bits, because some architectures
-	 * (e.g. x86_64 with iommu_sac_force set) will allow 40 bit
+	/* Set the PCI DMA mask.  Try all possibilities from our genuine mask
+	 * down to 32 bits, because some architectures will allow 40 bit
 	 * masks event though they reject 46 bit masks.
 	 */
 	while (dma_mask > 0x7fffffffUL) {
diff --git a/drivers/of/device.c b/drivers/of/device.c
index 064c818105bd..33d85511d790 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -76,6 +76,8 @@ int of_device_add(struct platform_device *ofdev)
  * of_dma_configure - Setup DMA configuration
  * @dev:	Device to apply DMA configuration
  * @np:		Pointer to OF node having DMA configuration
+ * @force_dma:  Whether device is to be set up by of_dma_configure() even if
+ *		DMA capability is not explicitly described by firmware.
  *
  * Try to get devices's DMA configuration from DT and update it
  * accordingly.
@@ -84,7 +86,7 @@ int of_device_add(struct platform_device *ofdev)
  * can use a platform bus notifier and handle BUS_NOTIFY_ADD_DEVICE events
  * to fix up DMA configuration.
  */
-int of_dma_configure(struct device *dev, struct device_node *np)
+int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
 {
 	u64 dma_addr, paddr, size = 0;
 	int ret;
@@ -100,7 +102,7 @@ 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->bus->force_dma)
+		if (!force_dma)
 			return ret == -ENODEV ? 0 : ret;
 
 		dma_addr = offset = 0;
diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 9a4f4246231d..895c83e0c7b6 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -353,7 +353,7 @@ int of_reserved_mem_device_init_by_idx(struct device *dev,
 		/* ensure that dma_ops is set for virtual devices
 		 * using reserved memory
 		 */
-		of_dma_configure(dev, np);
+		of_dma_configure(dev, np, true);
 
 		dev_info(dev, "assigned reserved memory node %s\n", rmem->name);
 	} else {
diff --git a/drivers/parisc/Kconfig b/drivers/parisc/Kconfig
index 3a102a84d637..5a48b5606110 100644
--- a/drivers/parisc/Kconfig
+++ b/drivers/parisc/Kconfig
@@ -103,11 +103,6 @@ config IOMMU_SBA
 	depends on PCI_LBA
 	default PCI_LBA
 
-config IOMMU_HELPER
-	bool
-	depends on IOMMU_SBA || IOMMU_CCIO
-	default y
-
 source "drivers/pcmcia/Kconfig"
 
 endmenu
diff --git a/drivers/parisc/ccio-dma.c b/drivers/parisc/ccio-dma.c
index d29cedb3f23b..614823617b8b 100644
--- a/drivers/parisc/ccio-dma.c
+++ b/drivers/parisc/ccio-dma.c
@@ -1570,8 +1570,6 @@ static int __init ccio_probe(struct parisc_device *dev)
 	}
 #endif
 	ioc_count++;
-
-	parisc_has_iommu();
 	return 0;
 }
 
diff --git a/drivers/parisc/sba_iommu.c b/drivers/parisc/sba_iommu.c
index 0d33d1f86d10..11de0eccf968 100644
--- a/drivers/parisc/sba_iommu.c
+++ b/drivers/parisc/sba_iommu.c
@@ -1989,8 +1989,6 @@ static int __init sba_driver_callback(struct parisc_device *dev)
 	proc_create_single("sba_iommu", 0, root, sba_proc_info);
 	proc_create_single("sba_iommu-bitmap", 0, root, sba_proc_bitmap_info);
 #endif
-
-	parisc_has_iommu();
 	return 0;
 }
 
diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index 34b56a8f8480..29a487f31dae 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -5,10 +5,6 @@
 
 source "drivers/pci/pcie/Kconfig"
 
-config PCI_BUS_ADDR_T_64BIT
-	def_bool y if (ARCH_DMA_ADDR_T_64BIT || 64BIT)
-	depends on PCI
-
 config PCI_MSI
 	bool "Message Signaled Interrupts (MSI and MSI-X)"
 	depends on PCI
diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index bc2ded4c451f..35b7fc87eac5 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -120,7 +120,7 @@ int devm_request_pci_bus_resources(struct device *dev,
 EXPORT_SYMBOL_GPL(devm_request_pci_bus_resources);
 
 static struct pci_bus_region pci_32_bit = {0, 0xffffffffULL};
-#ifdef CONFIG_PCI_BUS_ADDR_T_64BIT
+#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
 static struct pci_bus_region pci_64_bit = {0,
 				(pci_bus_addr_t) 0xffffffffffffffffULL};
 static struct pci_bus_region pci_high = {(pci_bus_addr_t) 0x100000000ULL,
@@ -230,7 +230,7 @@ int pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
 					  resource_size_t),
 		void *alignf_data)
 {
-#ifdef CONFIG_PCI_BUS_ADDR_T_64BIT
+#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
 	int rc;
 
 	if (res->flags & IORESOURCE_MEM_64) {
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index b9a131137e64..f8269a725667 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -16,6 +16,8 @@
 #include <linux/pm_runtime.h>
 #include <linux/suspend.h>
 #include <linux/kexec.h>
+#include <linux/of_device.h>
+#include <linux/acpi.h>
 #include "pci.h"
 #include "pcie/portdrv.h"
 
@@ -1577,6 +1579,35 @@ static int pci_bus_num_vf(struct device *dev)
 	return pci_num_vf(to_pci_dev(dev));
 }
 
+/**
+ * pci_dma_configure - Setup DMA configuration
+ * @dev: ptr to dev structure
+ *
+ * Function to update PCI devices's DMA configuration using the same
+ * info from the OF node or ACPI node of host bridge's parent (if any).
+ */
+static int pci_dma_configure(struct device *dev)
+{
+	struct device *bridge;
+	int ret = 0;
+
+	bridge = pci_get_host_bridge_device(to_pci_dev(dev));
+
+	if (IS_ENABLED(CONFIG_OF) && bridge->parent &&
+	    bridge->parent->of_node) {
+		ret = of_dma_configure(dev, bridge->parent->of_node, true);
+	} else if (has_acpi_companion(bridge)) {
+		struct acpi_device *adev = to_acpi_device_node(bridge->fwnode);
+		enum dev_dma_attr attr = acpi_get_dma_attr(adev);
+
+		if (attr != DEV_DMA_NOT_SUPPORTED)
+			ret = acpi_dma_configure(dev, attr);
+	}
+
+	pci_put_host_bridge_device(bridge);
+	return ret;
+}
+
 struct bus_type pci_bus_type = {
 	.name		= "pci",
 	.match		= pci_bus_match,
@@ -1589,7 +1620,7 @@ 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,
+	.dma_configure	= pci_dma_configure,
 };
 EXPORT_SYMBOL(pci_bus_type);
 
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index f125fd71c0f2..fb38aeff9dbd 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2149,27 +2149,6 @@ static int scsi_map_queues(struct blk_mq_tag_set *set)
 	return blk_mq_map_queues(set);
 }
 
-static u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
-{
-	struct device *host_dev;
-	u64 bounce_limit = 0xffffffff;
-
-	if (shost->unchecked_isa_dma)
-		return BLK_BOUNCE_ISA;
-	/*
-	 * Platforms with virtual-DMA translation
-	 * hardware have no practical limit.
-	 */
-	if (!PCI_DMA_BUS_IS_PHYS)
-		return BLK_BOUNCE_ANY;
-
-	host_dev = scsi_get_device(shost);
-	if (host_dev && host_dev->dma_mask)
-		bounce_limit = (u64)dma_max_pfn(host_dev) << PAGE_SHIFT;
-
-	return bounce_limit;
-}
-
 void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
 {
 	struct device *dev = shost->dma_dev;
@@ -2189,7 +2168,8 @@ void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
 	}
 
 	blk_queue_max_hw_sectors(q, shost->max_sectors);
-	blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
+	if (shost->unchecked_isa_dma)
+		blk_queue_bounce_limit(q, BLK_BOUNCE_ISA);
 	blk_queue_segment_boundary(q, shost->dma_boundary);
 	dma_set_seg_boundary(dev, shost->dma_boundary);