[PATCH 3/8] pseries/iommu: find windows after kexec during boot

[PATCH 3/8] pseries/iommu: find windows after kexec during boot

[Nishanth Aravamudan]

From: Milton Miller <miltonm@bga.com>

Move the discovery of windows previously setup from when the pci driver
calls set_dma_mask to an arch_initcall.

When kexecing into a kernel with dynamic dma windows allocated, we need
to find the windows early so that memory hot remove will be able to
delete the tces mapping the to be removed memory and memory hotplug add
will map the new memory into the window.  We should not wait for the
driver to be loaded and the device to be probed.  The iommu init hooks
are before kmalloc is setup, so defer to arch_initcall.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
---
 arch/powerpc/platforms/pseries/iommu.c |   52 ++++++++++++++-----------------
 1 files changed, 24 insertions(+), 28 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index a0421ac..a48f126 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -695,9 +695,9 @@ static void remove_ddw(struct device_node *np)
 			np->full_name, ret, ddr_avail[2], liobn);
 
 delprop:
-	ret = of_remove_property(np, win64);
+	ret = prom_remove_property(np, win64);
 	if (ret)
-		pr_warning("%s: failed to remove direct window property: %d\n"
+		pr_warning("%s: failed to remove direct window property: %d\n",
 			np->full_name, ret);
 }
 
@@ -725,38 +725,38 @@ static u64 dupe_ddw_if_already_created(struct pci_dev *dev, struct device_node *
 	return dma_addr;
 }
 
-static u64 dupe_ddw_if_kexec(struct pci_dev *dev, struct device_node *pdn)
+static int find_existing_ddw_windows(void)
 {
-	struct device_node *dn;
-	struct pci_dn *pcidn;
 	int len;
+	struct device_node *pdn;
 	struct direct_window *window;
 	const struct dynamic_dma_window_prop *direct64;
-	u64 dma_addr = 0;
 
-	dn = pci_device_to_OF_node(dev);
-	pcidn = PCI_DN(dn);
-	direct64 = of_get_property(pdn, DIRECT64_PROPNAME, &len);
-	if (direct64) {
-		if (len < sizeof(struct dynamic_dma_window_prop)) {
+	if (!firmware_has_feature(FW_FEATURE_LPAR))
+		return 0;
+
+	for_each_node_with_property(pdn, DIRECT64_PROPNAME) {
+		direct64 = of_get_property(pdn, DIRECT64_PROPNAME, &len);
+		if (!direct64)
+			continue;
+
+		window = kzalloc(sizeof(*window), GFP_KERNEL);
+		if (!window || len < sizeof(struct dynamic_dma_window_prop)) {
+			kfree(window);
 			remove_ddw(pdn);
-		} else {
-			window = kzalloc(sizeof(*window), GFP_KERNEL);
-			if (!window) {
-				remove_ddw(pdn);
-			} else {
-				window->device = pdn;
-				window->prop = direct64;
-				spin_lock(&direct_window_list_lock);
-				list_add(&window->list, &direct_window_list);
-				spin_unlock(&direct_window_list_lock);
-				dma_addr = direct64->dma_base;
-			}
+			continue;
 		}
+
+		window->device = pdn;
+		window->prop = direct64;
+		spin_lock(&direct_window_list_lock);
+		list_add(&window->list, &direct_window_list);
+		spin_unlock(&direct_window_list_lock);
 	}
 
-	return dma_addr;
+	return 0;
 }
+machine_arch_initcall(pseries, find_existing_ddw_windows);
 
 static int query_ddw(struct pci_dev *dev, const u32 *ddr_avail,
 			struct ddw_query_response *query)
@@ -854,10 +854,6 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	if (dma_addr != 0)
 		goto out_unlock;
 
-	dma_addr = dupe_ddw_if_kexec(dev, pdn);
-	if (dma_addr != 0)
-		goto out_unlock;
-
 	/*
 	 * the ibm,ddw-applicable property holds the tokens for:
 	 * ibm,query-pe-dma-window
-- 
1.7.4.1

[PATCH 4/8] pseries/iommu: cleanup ddw naming

[Nishanth Aravamudan]

From: Milton Miller <miltonm@bga.com>

When using a property refering to the availibily of dynamic dma windows
call it ddw_avail not ddr_avail.

dupe_ddw_if_already_created does not dupilcate anything, it only finds
and reuses the windows we already created, so rename it to
find_existing_ddw.  Also, it does not need the pci device node, so
remove that argument.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
---
 arch/powerpc/platforms/pseries/iommu.c |   42 ++++++++++++++-----------------
 1 files changed, 19 insertions(+), 23 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index a48f126..01faab9 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -659,16 +659,16 @@ static void remove_ddw(struct device_node *np)
 {
 	struct dynamic_dma_window_prop *dwp;
 	struct property *win64;
-	const u32 *ddr_avail;
+	const u32 *ddw_avail;
 	u64 liobn;
 	int len, ret;
 
-	ddr_avail = of_get_property(np, "ibm,ddw-applicable", &len);
+	ddw_avail = of_get_property(np, "ibm,ddw-applicable", &len);
 	win64 = of_find_property(np, DIRECT64_PROPNAME, NULL);
 	if (!win64)
 		return;
 
-	if (!ddr_avail || len < 3 * sizeof(u32) || win64->length < sizeof(*dwp))
+	if (!ddw_avail || len < 3 * sizeof(u32) || win64->length < sizeof(*dwp))
 		goto delprop;
 
 	dwp = win64->value;
@@ -684,15 +684,15 @@ static void remove_ddw(struct device_node *np)
 		pr_debug("%s successfully cleared tces in window.\n",
 			 np->full_name);
 
-	ret = rtas_call(ddr_avail[2], 1, 1, NULL, liobn);
+	ret = rtas_call(ddw_avail[2], 1, 1, NULL, liobn);
 	if (ret)
 		pr_warning("%s: failed to remove direct window: rtas returned "
 			"%d to ibm,remove-pe-dma-window(%x) %llx\n",
-			np->full_name, ret, ddr_avail[2], liobn);
+			np->full_name, ret, ddw_avail[2], liobn);
 	else
 		pr_debug("%s: successfully removed direct window: rtas returned "
 			"%d to ibm,remove-pe-dma-window(%x) %llx\n",
-			np->full_name, ret, ddr_avail[2], liobn);
+			np->full_name, ret, ddw_avail[2], liobn);
 
 delprop:
 	ret = prom_remove_property(np, win64);
@@ -701,16 +701,12 @@ delprop:
 			np->full_name, ret);
 }
 
-static u64 dupe_ddw_if_already_created(struct pci_dev *dev, struct device_node *pdn)
+static u64 find_existing_ddw(struct device_node *pdn)
 {
-	struct device_node *dn;
-	struct pci_dn *pcidn;
 	struct direct_window *window;
 	const struct dynamic_dma_window_prop *direct64;
 	u64 dma_addr = 0;
 
-	dn = pci_device_to_OF_node(dev);
-	pcidn = PCI_DN(dn);
 	spin_lock(&direct_window_list_lock);
 	/* check if we already created a window and dupe that config if so */
 	list_for_each_entry(window, &direct_window_list, list) {
@@ -758,7 +754,7 @@ static int find_existing_ddw_windows(void)
 }
 machine_arch_initcall(pseries, find_existing_ddw_windows);
 
-static int query_ddw(struct pci_dev *dev, const u32 *ddr_avail,
+static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
 			struct ddw_query_response *query)
 {
 	struct device_node *dn;
@@ -779,15 +775,15 @@ static int query_ddw(struct pci_dev *dev, const u32 *ddr_avail,
 	if (pcidn->eeh_pe_config_addr)
 		cfg_addr = pcidn->eeh_pe_config_addr;
 	buid = pcidn->phb->buid;
-	ret = rtas_call(ddr_avail[0], 3, 5, (u32 *)query,
+	ret = rtas_call(ddw_avail[0], 3, 5, (u32 *)query,
 		  cfg_addr, BUID_HI(buid), BUID_LO(buid));
 	dev_info(&dev->dev, "ibm,query-pe-dma-windows(%x) %x %x %x"
-		" returned %d\n", ddr_avail[0], cfg_addr, BUID_HI(buid),
+		" returned %d\n", ddw_avail[0], cfg_addr, BUID_HI(buid),
 		BUID_LO(buid), ret);
 	return ret;
 }
 
-static int create_ddw(struct pci_dev *dev, const u32 *ddr_avail,
+static int create_ddw(struct pci_dev *dev, const u32 *ddw_avail,
 			struct ddw_create_response *create, int page_shift,
 			int window_shift)
 {
@@ -812,12 +808,12 @@ static int create_ddw(struct pci_dev *dev, const u32 *ddr_avail,
 
 	do {
 		/* extra outputs are LIOBN and dma-addr (hi, lo) */
-		ret = rtas_call(ddr_avail[1], 5, 4, (u32 *)create, cfg_addr,
+		ret = rtas_call(ddw_avail[1], 5, 4, (u32 *)create, cfg_addr,
 				BUID_HI(buid), BUID_LO(buid), page_shift, window_shift);
 	} while (rtas_busy_delay(ret));
 	dev_info(&dev->dev,
 		"ibm,create-pe-dma-window(%x) %x %x %x %x %x returned %d "
-		"(liobn = 0x%x starting addr = %x %x)\n", ddr_avail[1],
+		"(liobn = 0x%x starting addr = %x %x)\n", ddw_avail[1],
 		 cfg_addr, BUID_HI(buid), BUID_LO(buid), page_shift,
 		 window_shift, ret, create->liobn, create->addr_hi, create->addr_lo);
 
@@ -843,14 +839,14 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	int page_shift;
 	u64 dma_addr, max_addr;
 	struct device_node *dn;
-	const u32 *uninitialized_var(ddr_avail);
+	const u32 *uninitialized_var(ddw_avail);
 	struct direct_window *window;
 	struct property *win64;
 	struct dynamic_dma_window_prop *ddwprop;
 
 	mutex_lock(&direct_window_init_mutex);
 
-	dma_addr = dupe_ddw_if_already_created(dev, pdn);
+	dma_addr = find_existing_ddw(pdn);
 	if (dma_addr != 0)
 		goto out_unlock;
 
@@ -862,8 +858,8 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	 * for the given node in that order.
 	 * the property is actually in the parent, not the PE
 	 */
-	ddr_avail = of_get_property(pdn, "ibm,ddw-applicable", &len);
-	if (!ddr_avail || len < 3 * sizeof(u32))
+	ddw_avail = of_get_property(pdn, "ibm,ddw-applicable", &len);
+	if (!ddw_avail || len < 3 * sizeof(u32))
 		goto out_unlock;
 
        /*
@@ -873,7 +869,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 	 * of page sizes: supported and supported for migrate-dma.
 	 */
 	dn = pci_device_to_OF_node(dev);
-	ret = query_ddw(dev, ddr_avail, &query);
+	ret = query_ddw(dev, ddw_avail, &query);
 	if (ret != 0)
 		goto out_unlock;
 
@@ -922,7 +918,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
 		goto out_free_prop;
 	}
 
-	ret = create_ddw(dev, ddr_avail, &create, page_shift, len);
+	ret = create_ddw(dev, ddw_avail, &create, page_shift, len);
 	if (ret != 0)
 		goto out_free_prop;
 
-- 
1.7.4.1

[PATCH 5/8] powerpc: override dma_get_required_mask by platform hook and ops

[Nishanth Aravamudan]

From: Milton Miller <miltonm@bga.com>

The hook dma_get_required_mask is supposed to return the mask required
by the platform to operate efficently.  The generic version of
dma_get_required_mask in driver/base/platform.c returns a mask based
only on max_pfn.  However, this is likely too big for iommu systems
and could be too small for platforms that require a dma offset or have
a secondary window at a high offset.

Override the default, provide a hook in ppc_md used by pseries lpar and
cell, and provide the default answer based on memblock_end_of_DRAM(),
with hooks for get_dma_offset, and provide an implementation for iommu
that looks at the defined table size.  Coverting from the end address
to the required bit mask is based on the generic implementation.

The need for this was discovered when the qla2xxx driver switched to
64 bit dma then reverted to 32 bit when dma_get_required_mask said
32 bits was sufficient.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
---
 arch/powerpc/include/asm/dma-mapping.h |    3 ++
 arch/powerpc/include/asm/machdep.h     |    3 +-
 arch/powerpc/kernel/dma-iommu.c        |   13 ++++++++++
 arch/powerpc/kernel/dma.c              |   39 ++++++++++++++++++++++++++++++++
 arch/powerpc/platforms/cell/iommu.c    |   12 +++++++++
 arch/powerpc/platforms/pseries/iommu.c |   27 ++++++++++++++++++++++
 6 files changed, 96 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h
index dd70fac..8135e66 100644
--- a/arch/powerpc/include/asm/dma-mapping.h
+++ b/arch/powerpc/include/asm/dma-mapping.h
@@ -20,6 +20,8 @@
 
 #define DMA_ERROR_CODE		(~(dma_addr_t)0x0)
 
+#define ARCH_HAS_DMA_GET_REQUIRED_MASK
+
 /* Some dma direct funcs must be visible for use in other dma_ops */
 extern void *dma_direct_alloc_coherent(struct device *dev, size_t size,
 				       dma_addr_t *dma_handle, gfp_t flag);
@@ -69,6 +71,7 @@ static inline unsigned long device_to_mask(struct device *dev)
  */
 #ifdef CONFIG_PPC64
 extern struct dma_map_ops dma_iommu_ops;
+extern u64 dma_iommu_get_required_mask(struct device *dev);
 #endif
 extern struct dma_map_ops dma_direct_ops;
 
diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index e4f0191..5837881 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -100,8 +100,9 @@ struct machdep_calls {
 	void		(*pci_dma_dev_setup)(struct pci_dev *dev);
 	void		(*pci_dma_bus_setup)(struct pci_bus *bus);
 
-	/* Platform set_dma_mask override */
+	/* Platform set_dma_mask and dma_get_required_mask overrides */
 	int		(*dma_set_mask)(struct device *dev, u64 dma_mask);
+	u64		(*dma_get_required_mask)(struct device *dev);
 
 	int		(*probe)(void);
 	void		(*setup_arch)(void); /* Optional, may be NULL */
diff --git a/arch/powerpc/kernel/dma-iommu.c b/arch/powerpc/kernel/dma-iommu.c
index e755415..1f2a711 100644
--- a/arch/powerpc/kernel/dma-iommu.c
+++ b/arch/powerpc/kernel/dma-iommu.c
@@ -90,6 +90,19 @@ static int dma_iommu_dma_supported(struct device *dev, u64 mask)
 		return 1;
 }
 
+u64 dma_iommu_get_required_mask(struct device *dev)
+{
+	struct iommu_table *tbl = get_iommu_table_base(dev);
+	u64 mask;
+	if (!tbl)
+		return 0;
+
+	mask = 1ULL < (fls_long(tbl->it_offset + tbl->it_size) - 1);
+	mask += mask - 1;
+
+	return mask;
+}
+
 struct dma_map_ops dma_iommu_ops = {
 	.alloc_coherent	= dma_iommu_alloc_coherent,
 	.free_coherent	= dma_iommu_free_coherent,
diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index d238c08..97fe867 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -172,6 +172,45 @@ int dma_set_mask(struct device *dev, u64 dma_mask)
 }
 EXPORT_SYMBOL(dma_set_mask);
 
+u64 dma_get_required_mask(struct device *dev)
+{
+	struct dma_map_ops *dma_ops = get_dma_ops(dev);
+	u64 mask, end = 0;
+
+	if (ppc_md.dma_get_required_mask)
+		return ppc_md.dma_get_required_mask(dev);
+
+	if (unlikely(dma_ops == NULL))
+		return 0;
+
+#ifdef CONFIG_PPC64
+	else if (dma_ops == &dma_iommu_ops)
+		return dma_iommu_get_required_mask(dev);
+#endif
+#ifdef CONFIG_SWIOTLB
+	else if (dma_ops == &swiotlb_dma_ops) {
+		u64 max_direct_dma_addr = dev->archdata.max_direct_dma_addr;
+
+		end = memblock_end_of_DRAM();
+		if (max_direct_dma_addr && end > max_direct_dma_addr)
+			end = max_direct_dma_addr;
+		end += get_dma_offset(dev);
+	}
+#endif
+	else if (dma_ops == &dma_direct_ops)
+		end = memblock_end_of_DRAM() + get_dma_offset(dev);
+	else {
+		WARN_ONCE(1, "%s: unknown ops %p\n", __func__, dma_ops);
+		end = memblock_end_of_DRAM();
+	}
+
+	mask = 1ULL << (fls64(end) - 1);
+	mask += mask - 1;
+
+	return mask;
+}
+EXPORT_SYMBOL_GPL(dma_get_required_mask);
+
 static int __init dma_init(void)
 {
        dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
diff --git a/arch/powerpc/platforms/cell/iommu.c b/arch/powerpc/platforms/cell/iommu.c
index 26a0671..5ef55f3 100644
--- a/arch/powerpc/platforms/cell/iommu.c
+++ b/arch/powerpc/platforms/cell/iommu.c
@@ -1159,6 +1159,17 @@ static int __init setup_iommu_fixed(char *str)
 }
 __setup("iommu_fixed=", setup_iommu_fixed);
 
+static u64 cell_dma_get_required_mask(struct device *dev)
+{
+	if (!dev->dma_mask)
+		return 0;
+
+	if (iommu_fixed_disabled && get_dma_ops(dev) == &dma_iommu_ops)
+		return dma_iommu_get_required_mask(dev);
+
+	return DMA_BIT_MASK(64);
+}
+
 static int __init cell_iommu_init(void)
 {
 	struct device_node *np;
@@ -1175,6 +1186,7 @@ static int __init cell_iommu_init(void)
 
 	/* Setup various ppc_md. callbacks */
 	ppc_md.pci_dma_dev_setup = cell_pci_dma_dev_setup;
+	ppc_md.dma_get_required_mask = cell_dma_get_required_mask;
 	ppc_md.tce_build = tce_build_cell;
 	ppc_md.tce_free = tce_free_cell;
 
diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 01faab9..fe5eded 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1077,12 +1077,38 @@ check_mask:
 	return 0;
 }
 
+static u64 dma_get_required_mask_pSeriesLP(struct device *dev)
+{
+	if (!dev->dma_mask)
+		return 0;
+
+	if (!disable_ddw && dev_is_pci(dev)) {
+		struct pci_dev *pdev = to_pci_dev(dev);
+		struct device_node *dn;
+
+		dn = pci_device_to_OF_node(pdev);
+
+		/* search upwards for ibm,dma-window */
+		for (; dn && PCI_DN(dn) && !PCI_DN(dn)->iommu_table;
+				dn = dn->parent)
+			if (of_get_property(dn, "ibm,dma-window", NULL))
+				break;
+		/* if there is a ibm,ddw-applicable property require 64 bits */
+		if (dn && PCI_DN(dn) &&
+				of_get_property(dn, "ibm,ddw-applicable", NULL))
+			return DMA_BIT_MASK(64);
+	}
+
+	return dma_iommu_get_required_mask(dev);
+}
+
 #else  /* CONFIG_PCI */
 #define pci_dma_bus_setup_pSeries	NULL
 #define pci_dma_dev_setup_pSeries	NULL
 #define pci_dma_bus_setup_pSeriesLP	NULL
 #define pci_dma_dev_setup_pSeriesLP	NULL
 #define dma_set_mask_pSeriesLP		NULL
+#define dma_get_required_mask_pSeriesLP	NULL
 #endif /* !CONFIG_PCI */
 
 static int iommu_mem_notifier(struct notifier_block *nb, unsigned long action,
@@ -1186,6 +1212,7 @@ void iommu_init_early_pSeries(void)
 		ppc_md.pci_dma_bus_setup = pci_dma_bus_setup_pSeriesLP;
 		ppc_md.pci_dma_dev_setup = pci_dma_dev_setup_pSeriesLP;
 		ppc_md.dma_set_mask = dma_set_mask_pSeriesLP;
+		ppc_md.dma_get_required_mask = dma_get_required_mask_pSeriesLP;
 	} else {
 		ppc_md.tce_build = tce_build_pSeries;
 		ppc_md.tce_free  = tce_free_pSeries;
-- 
1.7.4.1

Re: [PATCH 5/8] powerpc: override dma_get_required_mask by platform hook and ops

[Benjamin Herrenschmidt]

On Wed, 2011-05-11 at 15:25 -0700, Nishanth Aravamudan wrote:
> From: Milton Miller <miltonm-ogEGBHC/i9Y@public.gmane.org>
> 
> The hook dma_get_required_mask is supposed to return the mask required
> by the platform to operate efficently.  The generic version of
> dma_get_required_mask in driver/base/platform.c returns a mask based
> only on max_pfn.  However, this is likely too big for iommu systems
> and could be too small for platforms that require a dma offset or have
> a secondary window at a high offset.

The result of those 3 patches doesn't build on top of my current tree,
the generic dma_ops lacks the dma_get_required_mask hook. I'll have a
look again after the merge window.

Cheers,
Ben.

Re: [PATCH 5/8] powerpc: override dma_get_required_mask by platform hook and ops

[Nishanth Aravamudan]

On 19.05.2011 [17:43:56 +1000], Benjamin Herrenschmidt wrote:
> On Wed, 2011-05-11 at 15:25 -0700, Nishanth Aravamudan wrote:
> > From: Milton Miller <miltonm@bga.com>
> > 
> > The hook dma_get_required_mask is supposed to return the mask required
> > by the platform to operate efficently.  The generic version of
> > dma_get_required_mask in driver/base/platform.c returns a mask based
> > only on max_pfn.  However, this is likely too big for iommu systems
> > and could be too small for platforms that require a dma offset or have
> > a secondary window at a high offset.
> 
> The result of those 3 patches doesn't build on top of my current tree,
> the generic dma_ops lacks the dma_get_required_mask hook. I'll have a
> look again after the merge window.

Hrm, I think it's because for whatever reason [1] I forgot to cc you on 6/8?

https://lkml.org/lkml/2011/5/11/473

-Nish

[1] AKA over-reliance on get_maintainer.pl and lack of mental oversight!

-- 
Nishanth Aravamudan <nacc@us.ibm.com>
IBM Linux Technology Center

Re: [PATCH 5/8] powerpc: override dma_get_required_mask by platform hook and ops

[Nishanth Aravamudan]

Ben,

On 19.05.2011 [10:46:25 -0700], Nishanth Aravamudan wrote:
> On 19.05.2011 [17:43:56 +1000], Benjamin Herrenschmidt wrote:
> > On Wed, 2011-05-11 at 15:25 -0700, Nishanth Aravamudan wrote:
> > > From: Milton Miller <miltonm@bga.com>
> > > 
> > > The hook dma_get_required_mask is supposed to return the mask required
> > > by the platform to operate efficently.  The generic version of
> > > dma_get_required_mask in driver/base/platform.c returns a mask based
> > > only on max_pfn.  However, this is likely too big for iommu systems
> > > and could be too small for platforms that require a dma offset or have
> > > a secondary window at a high offset.
> > 
> > The result of those 3 patches doesn't build on top of my current tree,
> > the generic dma_ops lacks the dma_get_required_mask hook. I'll have a
> > look again after the merge window.
> 
> Hrm, I think it's because for whatever reason [1] I forgot to cc you on 6/8?
> 
> https://lkml.org/lkml/2011/5/11/473

Were you able to find the patch I refer to above?

Thanks,
Nish

-- 
Nishanth Aravamudan <nacc@us.ibm.com>
IBM Linux Technology Center