[PATCH v3 00/13] PCI: brcmstb: enable PCIe for STB chips

[PATCH v3 00/13] PCI: brcmstb: enable PCIe for STB chips

[Jim Quinlan via iommu]

v3:
  Commit "device core: Introduce multiple dma pfn offsets"
  Commit "arm: dma-mapping: Invoke dma offset func if needed"
  -- The above two commits have been squashed.  More importantly,
     the code has been modified so that the functionality for
     multiple pfn offsets subsumes the use of dev->dma_pfn_offset.
     In fact, dma_pfn_offset is removed and supplanted by
     dma_pfn_offset_map, which is a pointer to an array.  The
     more common case of a uniform offset is now handled as
     a map with a single entry, while cases requiring multiple
     pfn offsets use a map with multiple entries.  Code paths
     that used to do this:

         dev->dma_pfn_offset = mydrivers_pfn_offset;

     have been changed to do this:

         attach_uniform_dma_pfn_offset(dev, pfn_offset);

  Commit "dt-bindings: PCI: Add bindings for more Brcmstb chips"
  -- Add if/then clause for required props: resets, reset-names (RobH)
  -- Change compatible list from const to enum (RobH)
  -- Change list of u32-tuples to u64 (RobH)

  Commit "of: Include a dev param in of_dma_get_range()"
  -- modify of/unittests.c to add NULL param in of_dma_get_range() call.

  Commit "device core: Add ability to handle multiple dma offsets"
  -- align comment in device.h (AndyS).
  -- s/cpu_beg/cpu_start/ and s/dma_beg/dma_start/ in struct
     dma_pfn_offset_region (AndyS).

v2:
Commit: "device core: Add ability to handle multiple dma offsets"
  o Added helper func attach_dma_pfn_offset_map() in address.c (Chistoph)
  o Helpers funcs added to __phys_to_dma() & __dma_to_phys() (Christoph)
  o Added warning when multiple offsets are needed and !DMA_PFN_OFFSET_MAP
  o dev->dma_pfn_map => dev->dma_pfn_offset_map
  o s/frm/from/ for dma_pfn_offset_frm_{phys,dma}_addr() (Christoph)
  o In device.h: s/const void */const struct dma_pfn_offset_region */
  o removed 'unlikely' from unlikely(dev->dma_pfn_offset_map) since
    guarded by CONFIG_DMA_PFN_OFFSET_MAP (Christoph)
  o Since dev->dma_pfn_offset is copied in usb/core/{usb,message}.c, now
    dev->dma_pfn_offset_map is copied as well.
  o Merged two of the DMA commits into one (Christoph).

Commit "arm: dma-mapping: Invoke dma offset func if needed":
  o Use helper functions instead of #if CONFIG_DMA_PFN_OFFSET

Other commits' changes:
  o Removed need for carrying of_id var in priv (Nicolas)
  o Commit message rewordings (Bjorn)
  o Commit log messages filled to 75 chars (Bjorn)
  o devm_reset_control_get_shared())
    => devm_reset_control_get_optional_shared (Philipp)
  o Add call to reset_control_assert() in PCIe remove routines (Philipp)

v1:
This patchset expands the usefulness of the Broadcom Settop Box PCIe
controller by building upon the PCIe driver used currently by the
Raspbery Pi.  Other forms of this patchset were submitted by me years
ago and not accepted; the major sticking point was the code required
for the DMA remapping needed for the PCIe driver to work [1].

There have been many changes to the DMA and OF subsystems since that
time, making a cleaner and less intrusive patchset possible.  This
patchset implements a generalization of "dev->dma_pfn_offset", except
that instead of a single scalar offset it provides for multiple
offsets via a function which depends upon the "dma-ranges" property of
the PCIe host controller.  This is required for proper functionality
of the BrcmSTB PCIe controller and possibly some other devices.

[1] https://lore.kernel.org/linux-arm-kernel/1516058925-46522-5-git-send-email-jim2101024@gmail.com/

Jim Quinlan (13):
  PCI: brcmstb: PCIE_BRCMSTB depends on ARCH_BRCMSTB
  ata: ahci_brcm: Fix use of BCM7216 reset controller
  dt-bindings: PCI: Add bindings for more Brcmstb chips
  PCI: brcmstb: Add bcm7278 reigister info
  PCI: brcmstb: Add suspend and resume pm_ops
  PCI: brcmstb: Add bcm7278 PERST support
  PCI: brcmstb: Add control of rescal reset
  of: Include a dev param in of_dma_get_range()
  device core: Introduce multiple dma pfn offsets
  PCI: brcmstb: Set internal memory viewport sizes
  PCI: brcmstb: Accommodate MSI for older chips
  PCI: brcmstb: Set bus max burst size by chip type
  PCI: brcmstb: Add bcm7211, bcm7216, bcm7445, bcm7278 to match list

 .../bindings/pci/brcm,stb-pcie.yaml           |  58 ++-
 arch/arm/include/asm/dma-mapping.h            |   9 +-
 arch/arm/mach-keystone/keystone.c             |   9 +-
 arch/sh/drivers/pci/pcie-sh7786.c             |   3 +-
 arch/sh/kernel/dma-coherent.c                 |  17 +-
 arch/x86/pci/sta2x11-fixup.c                  |   7 +-
 drivers/acpi/arm64/iort.c                     |   5 +-
 drivers/ata/ahci_brcm.c                       |  14 +-
 drivers/gpu/drm/sun4i/sun4i_backend.c         |   7 +-
 drivers/iommu/io-pgtable-arm.c                |   2 +-
 .../platform/sunxi/sun4i-csi/sun4i_csi.c      |   5 +-
 .../platform/sunxi/sun6i-csi/sun6i_csi.c      |   5 +-
 drivers/of/address.c                          |  97 ++++-
 drivers/of/device.c                           |  10 +-
 drivers/of/of_private.h                       |   8 +-
 drivers/of/unittest.c                         |   2 +-
 drivers/pci/controller/Kconfig                |   3 +-
 drivers/pci/controller/pcie-brcmstb.c         | 408 +++++++++++++++---
 drivers/remoteproc/remoteproc_core.c          |   2 +-
 .../staging/media/sunxi/cedrus/cedrus_hw.c    |   7 +-
 drivers/usb/core/message.c                    |   4 +-
 drivers/usb/core/usb.c                        |   2 +-
 include/linux/device.h                        |   4 +-
 include/linux/dma-direct.h                    |  16 +-
 include/linux/dma-mapping.h                   |  45 ++
 kernel/dma/coherent.c                         |  11 +-
 26 files changed, 631 insertions(+), 129 deletions(-)

-- 
2.17.1

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[PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

[Jim Quinlan via iommu]

The new field in struct device 'dma_pfn_offset_map' is used to facilitate
the use of multiple pfn offsets between cpu addrs and dma addrs.  It
subsumes the role of dev->dma_pfn_offset -- a uniform offset -- and
designates the single offset a special case.

of_dma_configure() is the typical manner to set pfn offsets but there
are a number of ad hoc assignments to dev->dma_pfn_offset in the
kernel code.  These cases now invoke the function
attach_uniform_dma_pfn_offset(dev, pfn_offset).

Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
---
 arch/arm/include/asm/dma-mapping.h            |  9 +-
 arch/arm/mach-keystone/keystone.c             |  9 +-
 arch/sh/drivers/pci/pcie-sh7786.c             |  3 +-
 arch/sh/kernel/dma-coherent.c                 | 17 ++--
 arch/x86/pci/sta2x11-fixup.c                  |  7 +-
 drivers/acpi/arm64/iort.c                     |  5 +-
 drivers/gpu/drm/sun4i/sun4i_backend.c         |  7 +-
 drivers/iommu/io-pgtable-arm.c                |  2 +-
 .../platform/sunxi/sun4i-csi/sun4i_csi.c      |  5 +-
 .../platform/sunxi/sun6i-csi/sun6i_csi.c      |  5 +-
 drivers/of/address.c                          | 93 +++++++++++++++++--
 drivers/of/device.c                           |  8 +-
 drivers/remoteproc/remoteproc_core.c          |  2 +-
 .../staging/media/sunxi/cedrus/cedrus_hw.c    |  7 +-
 drivers/usb/core/message.c                    |  4 +-
 drivers/usb/core/usb.c                        |  2 +-
 include/linux/device.h                        |  4 +-
 include/linux/dma-direct.h                    | 16 +++-
 include/linux/dma-mapping.h                   | 45 +++++++++
 kernel/dma/coherent.c                         | 11 ++-
 20 files changed, 210 insertions(+), 51 deletions(-)

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index bdd80ddbca34..f1e72f99468b 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -35,8 +35,9 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 #ifndef __arch_pfn_to_dma
 static inline dma_addr_t pfn_to_dma(struct device *dev, unsigned long pfn)
 {
-	if (dev)
-		pfn -= dev->dma_pfn_offset;
+	if (dev && dev->dma_pfn_offset_map)
+		pfn -= dma_pfn_offset_from_phys_addr(dev, PFN_PHYS(pfn));
+
 	return (dma_addr_t)__pfn_to_bus(pfn);
 }
 
@@ -44,8 +45,8 @@ static inline unsigned long dma_to_pfn(struct device *dev, dma_addr_t addr)
 {
 	unsigned long pfn = __bus_to_pfn(addr);
 
-	if (dev)
-		pfn += dev->dma_pfn_offset;
+	if (dev && dev->dma_pfn_offset_map)
+		pfn += dma_pfn_offset_from_dma_addr(dev, addr);
 
 	return pfn;
 }
diff --git a/arch/arm/mach-keystone/keystone.c b/arch/arm/mach-keystone/keystone.c
index 638808c4e122..e7d3ee6e9cb5 100644
--- a/arch/arm/mach-keystone/keystone.c
+++ b/arch/arm/mach-keystone/keystone.c
@@ -8,6 +8,7 @@
  */
 #include <linux/io.h>
 #include <linux/of.h>
+#include <linux/dma-mapping.h>
 #include <linux/init.h>
 #include <linux/of_platform.h>
 #include <linux/of_address.h>
@@ -38,9 +39,11 @@ static int keystone_platform_notifier(struct notifier_block *nb,
 		return NOTIFY_BAD;
 
 	if (!dev->of_node) {
-		dev->dma_pfn_offset = keystone_dma_pfn_offset;
-		dev_err(dev, "set dma_pfn_offset%08lx\n",
-			dev->dma_pfn_offset);
+		int ret = attach_uniform_dma_pfn_offset
+				(dev, keystone_dma_pfn_offset);
+
+		dev_err(dev, "set dma_pfn_offset%08lx%s\n",
+			dev->dma_pfn_offset, ret ? " failed" : "");
 	}
 	return NOTIFY_OK;
 }
diff --git a/arch/sh/drivers/pci/pcie-sh7786.c b/arch/sh/drivers/pci/pcie-sh7786.c
index e0b568aaa701..2e832a5c58c1 100644
--- a/arch/sh/drivers/pci/pcie-sh7786.c
+++ b/arch/sh/drivers/pci/pcie-sh7786.c
@@ -12,6 +12,7 @@
 #include <linux/io.h>
 #include <linux/async.h>
 #include <linux/delay.h>
+#include <linux/dma-mapping.h>
 #include <linux/slab.h>
 #include <linux/clk.h>
 #include <linux/sh_clk.h>
@@ -487,7 +488,7 @@ int pcibios_map_platform_irq(const struct pci_dev *pdev, u8 slot, u8 pin)
 
 void pcibios_bus_add_device(struct pci_dev *pdev)
 {
-	pdev->dev.dma_pfn_offset = dma_pfn_offset;
+	attach_uniform_dma_pfn_offset(&pdev->dev, dma_pfn_offset);
 }
 
 static int __init sh7786_pcie_core_init(void)
diff --git a/arch/sh/kernel/dma-coherent.c b/arch/sh/kernel/dma-coherent.c
index d4811691b93c..5fc9e358b6c7 100644
--- a/arch/sh/kernel/dma-coherent.c
+++ b/arch/sh/kernel/dma-coherent.c
@@ -14,6 +14,8 @@ void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
 {
 	void *ret, *ret_nocache;
 	int order = get_order(size);
+	unsigned long pfn;
+	phys_addr_t phys;
 
 	gfp |= __GFP_ZERO;
 
@@ -34,11 +36,14 @@ void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
 		return NULL;
 	}
 
-	split_page(pfn_to_page(virt_to_phys(ret) >> PAGE_SHIFT), order);
+	phys = virt_to_phys(ret);
+	pfn =  phys >> PAGE_SHIFT;
+	split_page(pfn_to_page(pfn), order);
 
-	*dma_handle = virt_to_phys(ret);
-	if (!WARN_ON(!dev))
-		*dma_handle -= PFN_PHYS(dev->dma_pfn_offset);
+	*dma_handle = (dma_addr_t)phys;
+	if (!WARN_ON(!dev) && dev->dma_pfn_offset_map)
+		*dma_handle -= PFN_PHYS(
+			dma_pfn_offset_from_phys_addr(dev, phys));
 
 	return ret_nocache;
 }
@@ -50,8 +55,8 @@ void arch_dma_free(struct device *dev, size_t size, void *vaddr,
 	unsigned long pfn = (dma_handle >> PAGE_SHIFT);
 	int k;
 
-	if (!WARN_ON(!dev))
-		pfn += dev->dma_pfn_offset;
+	if (!WARN_ON(!dev) && dev->dma_pfn_offset_map)
+		pfn += dma_pfn_offset_from_dma_addr(dev, dma_handle);
 
 	for (k = 0; k < (1 << order); k++)
 		__free_pages(pfn_to_page(pfn + k), 0);
diff --git a/arch/x86/pci/sta2x11-fixup.c b/arch/x86/pci/sta2x11-fixup.c
index c313d784efab..4cdeca9f69b6 100644
--- a/arch/x86/pci/sta2x11-fixup.c
+++ b/arch/x86/pci/sta2x11-fixup.c
@@ -12,6 +12,7 @@
 #include <linux/export.h>
 #include <linux/list.h>
 #include <linux/dma-direct.h>
+#include <linux/dma-mapping.h>
 #include <asm/iommu.h>
 
 #define STA2X11_SWIOTLB_SIZE (4*1024*1024)
@@ -133,7 +134,7 @@ static void sta2x11_map_ep(struct pci_dev *pdev)
 	struct sta2x11_instance *instance = sta2x11_pdev_to_instance(pdev);
 	struct device *dev = &pdev->dev;
 	u32 amba_base, max_amba_addr;
-	int i;
+	int i, ret;
 
 	if (!instance)
 		return;
@@ -141,7 +142,9 @@ static void sta2x11_map_ep(struct pci_dev *pdev)
 	pci_read_config_dword(pdev, AHB_BASE(0), &amba_base);
 	max_amba_addr = amba_base + STA2X11_AMBA_SIZE - 1;
 
-	dev->dma_pfn_offset = PFN_DOWN(-amba_base);
+	ret = attach_uniform_dma_pfn_offset(dev, PFN_DOWN(-amba_base));
+	if (ret)
+		dev_err(dev, "sta2x11: could not set PFN offset\n");
 
 	dev->bus_dma_limit = max_amba_addr;
 	pci_set_consistent_dma_mask(pdev, max_amba_addr);
diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 28a6b387e80e..153661ddc74b 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -1142,8 +1142,9 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
 	*dma_addr = dmaaddr;
 	*dma_size = size;
 
-	dev->dma_pfn_offset = PFN_DOWN(offset);
-	dev_dbg(dev, "dma_pfn_offset(%#08llx)\n", offset);
+	ret = attach_uniform_dma_pfn_offset(dev, PFN_DOWN(offset));
+	dev_dbg(dev, "dma_pfn_offset(%#08llx)%s\n",
+		offset, ret ? " failed!" : "");
 }
 
 static void __init acpi_iort_register_irq(int hwirq, const char *name,
diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c b/drivers/gpu/drm/sun4i/sun4i_backend.c
index 072ea113e6be..3d41dfc7d178 100644
--- a/drivers/gpu/drm/sun4i/sun4i_backend.c
+++ b/drivers/gpu/drm/sun4i/sun4i_backend.c
@@ -11,6 +11,7 @@
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/of_graph.h>
+#include <linux/dma-mapping.h>
 #include <linux/platform_device.h>
 #include <linux/reset.h>
 
@@ -786,7 +787,7 @@ static int sun4i_backend_bind(struct device *dev, struct device *master,
 	const struct sun4i_backend_quirks *quirks;
 	struct resource *res;
 	void __iomem *regs;
-	int i, ret;
+	int i, ret = 0;
 
 	backend = devm_kzalloc(dev, sizeof(*backend), GFP_KERNEL);
 	if (!backend)
@@ -812,7 +813,9 @@ static int sun4i_backend_bind(struct device *dev, struct device *master,
 		 * on our device since the RAM mapping is at 0 for the DMA bus,
 		 * unlike the CPU.
 		 */
-		drm->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
+		ret = attach_uniform_dma_pfn_offset(dev, PHYS_PFN_OFFSET);
+		if (ret)
+			return ret;
 	}
 
 	backend->engine.node = dev->of_node;
diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 04fbd4bf0ff9..e9cc1c2d47cd 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -754,7 +754,7 @@ arm_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg)
 	if (cfg->oas > ARM_LPAE_MAX_ADDR_BITS)
 		return NULL;
 
-	if (!selftest_running && cfg->iommu_dev->dma_pfn_offset) {
+	if (!selftest_running && cfg->iommu_dev->dma_pfn_offset_map) {
 		dev_err(cfg->iommu_dev, "Cannot accommodate DMA offset for IOMMU page tables\n");
 		return NULL;
 	}
diff --git a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
index eff34ded6305..7212da5e1076 100644
--- a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
+++ b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/clk.h>
+#include <linux/dma-mapping.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
@@ -183,7 +184,9 @@ static int sun4i_csi_probe(struct platform_device *pdev)
 			return ret;
 	} else {
 #ifdef PHYS_PFN_OFFSET
-		csi->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
+		ret = attach_uniform_dma_pfn_offset(dev, PHYS_PFN_OFFSET);
+		if (ret)
+			return ret;
 #endif
 	}
 
diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
index 055eb0b8e396..2d66d415b6c3 100644
--- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
+++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
@@ -898,7 +898,10 @@ static int sun6i_csi_probe(struct platform_device *pdev)
 
 	sdev->dev = &pdev->dev;
 	/* The DMA bus has the memory mapped at 0 */
-	sdev->dev->dma_pfn_offset = PHYS_OFFSET >> PAGE_SHIFT;
+	ret = attach_uniform_dma_pfn_offset(sdev->dev,
+					    PHYS_OFFSET >> PAGE_SHIFT);
+	if (ret)
+		return ret;
 
 	ret = sun6i_csi_resource_request(sdev, pdev);
 	if (ret)
diff --git a/drivers/of/address.c b/drivers/of/address.c
index 96d8cfb14a60..c89333b0a5fb 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -918,6 +918,70 @@ void __iomem *of_io_request_and_map(struct device_node *np, int index,
 }
 EXPORT_SYMBOL(of_io_request_and_map);
 
+static int attach_dma_pfn_offset_map(struct device *dev,
+				     struct device_node *node, int num_ranges)
+{
+	struct of_range_parser parser;
+	struct of_range range;
+	struct dma_pfn_offset_region *r;
+
+	r = devm_kcalloc(dev, num_ranges + 1,
+			 sizeof(struct dma_pfn_offset_region), GFP_KERNEL);
+	if (!r)
+		return -ENOMEM;
+	dev->dma_pfn_offset_map = r;
+	of_dma_range_parser_init(&parser, node);
+
+	/*
+	 * Record all info for DMA ranges array.  We could
+	 * just use the of_range struct, but if we did that it
+	 * would require more calculations for phys_to_dma and
+	 * dma_to_phys conversions.
+	 */
+	for_each_of_range(&parser, &range) {
+		r->cpu_start = range.cpu_addr;
+		r->cpu_end = r->cpu_start + range.size - 1;
+		r->dma_start = range.bus_addr;
+		r->dma_end = r->dma_start + range.size - 1;
+		r->pfn_offset = PFN_DOWN(range.cpu_addr)
+			- PFN_DOWN(range.bus_addr);
+		r++;
+	}
+	return 0;
+}
+
+
+
+/**
+ * attach_dma_pfn_offset - Assign scalar offset for all addresses.
+ * @dev:	device pointer; only needed for a corner case.
+ * @dma_pfn_offset:	offset to apply when converting from phys addr
+ *			to dma addr and vice versa.
+ *
+ * It returns -ENOMEM if out of memory, otherwise 0.
+ */
+int attach_uniform_dma_pfn_offset(struct device *dev, unsigned long pfn_offset)
+{
+	struct dma_pfn_offset_region *r;
+
+	if (!dev)
+		return -ENODEV;
+
+	if (!pfn_offset)
+		return 0;
+
+	r = devm_kcalloc(dev, 1, sizeof(struct dma_pfn_offset_region),
+			 GFP_KERNEL);
+	if (!r)
+		return -ENOMEM;
+
+	r->uniform_offset = true;
+	r->pfn_offset = pfn_offset;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(attach_uniform_dma_pfn_offset);
+
 /**
  * of_dma_get_range - Get DMA range info
  * @dev:	device pointer; only needed for a corner case.
@@ -933,7 +997,7 @@ EXPORT_SYMBOL(of_io_request_and_map);
  *	CPU addr (phys_addr_t)	: pna cells
  *	size			: nsize cells
  *
- * It returns -ENODEV if "dma-ranges" property was not found
+ * It returns -ENODEV if !dev or "dma-ranges" property was not found
  * for this device in DT.
  */
 int of_dma_get_range(struct device *dev, struct device_node *np, u64 *dma_addr,
@@ -946,7 +1010,13 @@ int of_dma_get_range(struct device *dev, struct device_node *np, u64 *dma_addr,
 	bool found_dma_ranges = false;
 	struct of_range_parser parser;
 	struct of_range range;
+	phys_addr_t cpu_start = ~(phys_addr_t)0;
 	u64 dma_start = U64_MAX, dma_end = 0, dma_offset = 0;
+	bool dma_multi_pfn_offset = false;
+	int num_ranges = 0;
+
+	if (!dev)
+		return -ENODEV;
 
 	while (node) {
 		ranges = of_get_property(node, "dma-ranges", &len);
@@ -977,11 +1047,10 @@ int of_dma_get_range(struct device *dev, struct device_node *np, u64 *dma_addr,
 		pr_debug("dma_addr(%llx) cpu_addr(%llx) size(%llx)\n",
 			 range.bus_addr, range.cpu_addr, range.size);
 
-		if (dma_offset && range.cpu_addr - range.bus_addr != dma_offset) {
-			pr_warn("Can't handle multiple dma-ranges with different offsets on node(%pOF)\n", node);
-			/* Don't error out as we'd break some existing DTs */
-			continue;
-		}
+		num_ranges++;
+		if (dma_offset && range.cpu_addr - range.bus_addr != dma_offset)
+			dma_multi_pfn_offset = true;
+
 		dma_offset = range.cpu_addr - range.bus_addr;
 
 		/* Take lower and upper limits */
@@ -989,6 +1058,8 @@ int of_dma_get_range(struct device *dev, struct device_node *np, u64 *dma_addr,
 			dma_start = range.bus_addr;
 		if (range.bus_addr + range.size > dma_end)
 			dma_end = range.bus_addr + range.size;
+		if (range.cpu_addr < cpu_start)
+			cpu_start = range.cpu_addr;
 	}
 
 	if (dma_start >= dma_end) {
@@ -998,9 +1069,17 @@ int of_dma_get_range(struct device *dev, struct device_node *np, u64 *dma_addr,
 		goto out;
 	}
 
+	if (dma_multi_pfn_offset)
+		ret = attach_dma_pfn_offset_map(dev, node, num_ranges);
+	else if (dma_offset)
+		ret = attach_uniform_dma_pfn_offset(dev, PFN_DOWN(dma_offset));
+
+	if (ret)
+		goto out;
+
 	*dma_addr = dma_start;
 	*size = dma_end - dma_start;
-	*paddr = dma_start + dma_offset;
+	*paddr = cpu_start;
 
 	pr_debug("final: dma_addr(%llx) cpu_addr(%llx) size(%llx)\n",
 		 *dma_addr, *paddr, *size);
diff --git a/drivers/of/device.c b/drivers/of/device.c
index ef6a741f9f0b..91c50f40a82e 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -91,7 +91,6 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
 	u64 dma_addr, paddr, size = 0;
 	int ret;
 	bool coherent;
-	unsigned long offset;
 	const struct iommu_ops *iommu;
 	u64 mask, end;
 
@@ -105,10 +104,8 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
 		if (!force_dma)
 			return ret == -ENODEV ? 0 : ret;
 
-		dma_addr = offset = 0;
+		dma_addr = 0;
 	} else {
-		offset = PFN_DOWN(paddr - dma_addr);
-
 		/*
 		 * Add a work around to treat the size as mask + 1 in case
 		 * it is defined in DT as a mask.
@@ -123,7 +120,6 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
 			dev_err(dev, "Adjusted size 0x%llx invalid\n", size);
 			return -EINVAL;
 		}
-		dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset);
 	}
 
 	/*
@@ -142,8 +138,6 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
 	else if (!size)
 		size = 1ULL << 32;
 
-	dev->dma_pfn_offset = offset;
-
 	/*
 	 * Limit coherent and dma mask based on size and default mask
 	 * set by the driver.
diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index e12a54e67588..e49648f77261 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -518,7 +518,7 @@ static int rproc_handle_vdev(struct rproc *rproc, struct fw_rsc_vdev *rsc,
 	/* Initialise vdev subdevice */
 	snprintf(name, sizeof(name), "vdev%dbuffer", rvdev->index);
 	rvdev->dev.parent = rproc->dev.parent;
-	rvdev->dev.dma_pfn_offset = rproc->dev.parent->dma_pfn_offset;
+	rvdev->dev.dma_pfn_offset_map = rproc->dev.parent->dma_pfn_offset_map;
 	rvdev->dev.release = rproc_rvdev_release;
 	dev_set_name(&rvdev->dev, "%s#%s", dev_name(rvdev->dev.parent), name);
 	dev_set_drvdata(&rvdev->dev, rvdev);
diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_hw.c b/drivers/staging/media/sunxi/cedrus/cedrus_hw.c
index daf5f244f93b..29217e6e4153 100644
--- a/drivers/staging/media/sunxi/cedrus/cedrus_hw.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus_hw.c
@@ -171,8 +171,11 @@ int cedrus_hw_probe(struct cedrus_dev *dev)
 	 */
 
 #ifdef PHYS_PFN_OFFSET
-	if (!(variant->quirks & CEDRUS_QUIRK_NO_DMA_OFFSET))
-		dev->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
+	if (!(variant->quirks & CEDRUS_QUIRK_NO_DMA_OFFSET)) {
+		ret = attach_uniform_dma_pfn_offset(dev, PHYS_PFN_OFFSET);
+		if (ret)
+			return ret;
+	}
 #endif
 
 	ret = of_reserved_mem_device_init(dev->dev);
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 6197938dcc2d..071856000428 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1956,10 +1956,10 @@ int usb_set_configuration(struct usb_device *dev, int configuration)
 		intf->dev.groups = usb_interface_groups;
 		/*
 		 * Please refer to usb_alloc_dev() to see why we set
-		 * dma_mask and dma_pfn_offset.
+		 * dma_mask and dma_pfn_offset_map.
 		 */
 		intf->dev.dma_mask = dev->dev.dma_mask;
-		intf->dev.dma_pfn_offset = dev->dev.dma_pfn_offset;
+		intf->dev.dma_pfn_offset_map = dev->dev.dma_pfn_offset_map;
 		INIT_WORK(&intf->reset_ws, __usb_queue_reset_device);
 		intf->minor = -1;
 		device_initialize(&intf->dev);
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index f16c26dc079d..3fbc0c06ce9c 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -611,7 +611,7 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
 	 * mask for the entire HCD, so don't do that.
 	 */
 	dev->dev.dma_mask = bus->sysdev->dma_mask;
-	dev->dev.dma_pfn_offset = bus->sysdev->dma_pfn_offset;
+	dev->dev.dma_pfn_offset_map = bus->sysdev->dma_pfn_offset_map;
 	set_dev_node(&dev->dev, dev_to_node(bus->sysdev));
 	dev->state = USB_STATE_ATTACHED;
 	dev->lpm_disable_count = 1;
diff --git a/include/linux/device.h b/include/linux/device.h
index ac8e37cd716a..9c079643ff54 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -492,7 +492,7 @@ struct dev_links_info {
  * 		such descriptors.
  * @bus_dma_limit: Limit of an upstream bridge or bus which imposes a smaller
  *		DMA limit than the device itself supports.
- * @dma_pfn_offset: offset of DMA memory range relatively of RAM
+ * @dma_pfn_offset_map: offset map for DMA memory range relatively of RAM
  * @dma_parms:	A low level driver may set these to teach IOMMU code about
  * 		segment limitations.
  * @dma_pools:	Dma pools (if dma'ble device).
@@ -577,7 +577,7 @@ struct device {
 					     64 bit addresses for consistent
 					     allocations such descriptors. */
 	u64		bus_dma_limit;	/* upstream dma constraint */
-	unsigned long	dma_pfn_offset;
+	struct dma_pfn_offset_region *dma_pfn_offset_map;
 
 	struct device_dma_parameters *dma_parms;
 
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index 24b8684aa21d..3c3363a3925e 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -15,14 +15,26 @@ static inline dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
 {
 	dma_addr_t dev_addr = (dma_addr_t)paddr;
 
-	return dev_addr - ((dma_addr_t)dev->dma_pfn_offset << PAGE_SHIFT);
+	if (dev->dma_pfn_offset_map) {
+		unsigned long dma_pfn_offset
+			= dma_pfn_offset_from_phys_addr(dev, paddr);
+
+		dev_addr -= ((dma_addr_t)dma_pfn_offset << PAGE_SHIFT);
+	}
+	return dev_addr;
 }
 
 static inline phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t dev_addr)
 {
 	phys_addr_t paddr = (phys_addr_t)dev_addr;
 
-	return paddr + ((phys_addr_t)dev->dma_pfn_offset << PAGE_SHIFT);
+	if (dev->dma_pfn_offset_map) {
+		unsigned long dma_pfn_offset
+			= dma_pfn_offset_from_dma_addr(dev, dev_addr);
+
+		paddr += ((phys_addr_t)dma_pfn_offset << PAGE_SHIFT);
+	}
+	return paddr;
 }
 #endif /* !CONFIG_ARCH_HAS_PHYS_TO_DMA */
 
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 330ad58fbf4d..e0c2ec07c00a 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -256,6 +256,46 @@ static inline void dma_direct_sync_sg_for_cpu(struct device *dev,
 size_t dma_direct_max_mapping_size(struct device *dev);
 
 #ifdef CONFIG_HAS_DMA
+struct dma_pfn_offset_region {
+	bool		uniform_offset;
+	phys_addr_t	cpu_start;
+	phys_addr_t	cpu_end;
+	dma_addr_t	dma_start;
+	dma_addr_t	dma_end;
+	unsigned long	pfn_offset;
+};
+
+int attach_uniform_dma_pfn_offset(struct device *dev,
+				  unsigned long dma_pfn_offset);
+
+static inline unsigned long dma_pfn_offset_from_dma_addr(struct device *dev,
+							 dma_addr_t dma_addr)
+{
+	const struct dma_pfn_offset_region *m = dev->dma_pfn_offset_map;
+
+	if (m->uniform_offset)
+		return m->pfn_offset;
+
+	for (; m->cpu_end; m++)
+		if (dma_addr >= m->dma_start && dma_addr <= m->dma_end)
+			return m->pfn_offset;
+	return 0;
+}
+
+static inline unsigned long dma_pfn_offset_from_phys_addr(struct device *dev,
+							  phys_addr_t paddr)
+{
+	const struct dma_pfn_offset_region *m = dev->dma_pfn_offset_map;
+
+	if (m->uniform_offset)
+		return m->pfn_offset;
+
+	for (; m->cpu_end; m++)
+		if (paddr >= m->cpu_start && paddr <= m->cpu_end)
+			return m->pfn_offset;
+	return 0;
+}
+
 #include <asm/dma-mapping.h>
 
 static inline const struct dma_map_ops *get_dma_ops(struct device *dev)
@@ -463,6 +503,11 @@ u64 dma_get_required_mask(struct device *dev);
 size_t dma_max_mapping_size(struct device *dev);
 unsigned long dma_get_merge_boundary(struct device *dev);
 #else /* CONFIG_HAS_DMA */
+static inline int attach_uniform_dma_pfn_offset(struct device *dev,
+						unsigned long dma_pfn_offset)
+{
+	return -EIO;
+}
 static inline dma_addr_t dma_map_page_attrs(struct device *dev,
 		struct page *page, size_t offset, size_t size,
 		enum dma_data_direction dir, unsigned long attrs)
diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
index 2a0c4985f38e..20fc48d0b9d7 100644
--- a/kernel/dma/coherent.c
+++ b/kernel/dma/coherent.c
@@ -31,10 +31,13 @@ static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *de
 static inline dma_addr_t dma_get_device_base(struct device *dev,
 					     struct dma_coherent_mem * mem)
 {
-	if (mem->use_dev_dma_pfn_offset)
-		return (mem->pfn_base - dev->dma_pfn_offset) << PAGE_SHIFT;
-	else
-		return mem->device_base;
+	if (mem->use_dev_dma_pfn_offset && dev->dma_pfn_offset_map) {
+		unsigned long dma_pfn_offset = dma_pfn_offset_from_phys_addr
+			(dev, PFN_PHYS(mem->pfn_base));
+
+		return (mem->pfn_base - dma_pfn_offset) << PAGE_SHIFT;
+	}
+	return mem->device_base;
 }
 
 static int dma_init_coherent_memory(phys_addr_t phys_addr,
-- 
2.17.1

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Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

[Dan Carpenter]

On Wed, Jun 03, 2020 at 03:20:41PM -0400, Jim Quinlan wrote:
> @@ -786,7 +787,7 @@ static int sun4i_backend_bind(struct device *dev, struct device *master,
>  	const struct sun4i_backend_quirks *quirks;
>  	struct resource *res;
>  	void __iomem *regs;
> -	int i, ret;
> +	int i, ret = 0;

No need for this.

>  
>  	backend = devm_kzalloc(dev, sizeof(*backend), GFP_KERNEL);
>  	if (!backend)
> @@ -812,7 +813,9 @@ static int sun4i_backend_bind(struct device *dev, struct device *master,
>  		 * on our device since the RAM mapping is at 0 for the DMA bus,
>  		 * unlike the CPU.
>  		 */
> -		drm->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
> +		ret = attach_uniform_dma_pfn_offset(dev, PHYS_PFN_OFFSET);
> +		if (ret)
> +			return ret;
>  	}
>  
>  	backend->engine.node = dev->of_node;
> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index 04fbd4bf0ff9..e9cc1c2d47cd 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -754,7 +754,7 @@ arm_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg)
>  	if (cfg->oas > ARM_LPAE_MAX_ADDR_BITS)
>  		return NULL;
>  
> -	if (!selftest_running && cfg->iommu_dev->dma_pfn_offset) {
> +	if (!selftest_running && cfg->iommu_dev->dma_pfn_offset_map) {
>  		dev_err(cfg->iommu_dev, "Cannot accommodate DMA offset for IOMMU page tables\n");
>  		return NULL;
>  	}
> diff --git a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> index eff34ded6305..7212da5e1076 100644
> --- a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> +++ b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> @@ -7,6 +7,7 @@
>   */
>  
>  #include <linux/clk.h>
> +#include <linux/dma-mapping.h>
>  #include <linux/interrupt.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
> @@ -183,7 +184,9 @@ static int sun4i_csi_probe(struct platform_device *pdev)
>  			return ret;
>  	} else {
>  #ifdef PHYS_PFN_OFFSET
> -		csi->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
> +		ret = attach_uniform_dma_pfn_offset(dev, PHYS_PFN_OFFSET);
> +		if (ret)
> +			return ret;
>  #endif
>  	}
>  
> diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> index 055eb0b8e396..2d66d415b6c3 100644
> --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> @@ -898,7 +898,10 @@ static int sun6i_csi_probe(struct platform_device *pdev)
>  
>  	sdev->dev = &pdev->dev;
>  	/* The DMA bus has the memory mapped at 0 */
> -	sdev->dev->dma_pfn_offset = PHYS_OFFSET >> PAGE_SHIFT;
> +	ret = attach_uniform_dma_pfn_offset(sdev->dev,
> +					    PHYS_OFFSET >> PAGE_SHIFT);
> +	if (ret)
> +		return ret;
>  
>  	ret = sun6i_csi_resource_request(sdev, pdev);
>  	if (ret)
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index 96d8cfb14a60..c89333b0a5fb 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -918,6 +918,70 @@ void __iomem *of_io_request_and_map(struct device_node *np, int index,
>  }
>  EXPORT_SYMBOL(of_io_request_and_map);
>  
> +static int attach_dma_pfn_offset_map(struct device *dev,
> +				     struct device_node *node, int num_ranges)
> +{
> +	struct of_range_parser parser;
> +	struct of_range range;
> +	struct dma_pfn_offset_region *r;
> +
> +	r = devm_kcalloc(dev, num_ranges + 1,
> +			 sizeof(struct dma_pfn_offset_region), GFP_KERNEL);
> +	if (!r)
> +		return -ENOMEM;
> +	dev->dma_pfn_offset_map = r;
> +	of_dma_range_parser_init(&parser, node);
> +
> +	/*
> +	 * Record all info for DMA ranges array.  We could
> +	 * just use the of_range struct, but if we did that it
> +	 * would require more calculations for phys_to_dma and
> +	 * dma_to_phys conversions.
> +	 */
> +	for_each_of_range(&parser, &range) {
> +		r->cpu_start = range.cpu_addr;
> +		r->cpu_end = r->cpu_start + range.size - 1;
> +		r->dma_start = range.bus_addr;
> +		r->dma_end = r->dma_start + range.size - 1;
> +		r->pfn_offset = PFN_DOWN(range.cpu_addr)
> +			- PFN_DOWN(range.bus_addr);
> +		r++;
> +	}
> +	return 0;
> +}
> +
> +
> +
> +/**
> + * attach_dma_pfn_offset - Assign scalar offset for all addresses.
> + * @dev:	device pointer; only needed for a corner case.
> + * @dma_pfn_offset:	offset to apply when converting from phys addr
      ^^^^^^^^^^^^^^^
This parameter name does not match.

> + *			to dma addr and vice versa.
> + *
> + * It returns -ENOMEM if out of memory, otherwise 0.

It can also return -ENODEV.  Why are we passing NULL dev pointers to
all these functions anyway?

> + */
> +int attach_uniform_dma_pfn_offset(struct device *dev, unsigned long pfn_offset)
> +{
> +	struct dma_pfn_offset_region *r;
> +
> +	if (!dev)
> +		return -ENODEV;
> +
> +	if (!pfn_offset)
> +		return 0;
> +
> +	r = devm_kcalloc(dev, 1, sizeof(struct dma_pfn_offset_region),
> +			 GFP_KERNEL);

Use:	r = devm_kzalloc(dev, sizeof(*r), GFP_KERNEL);


> +	if (!r)
> +		return -ENOMEM;
> +
> +	r->uniform_offset = true;
> +	r->pfn_offset = pfn_offset;
> +
> +	return 0;
> +}

This function doesn't seem to do anything useful.  Is part of it
missing?

> +EXPORT_SYMBOL_GPL(attach_uniform_dma_pfn_offset);
> +

regards,
dan carpenter

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Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

[Jim Quinlan via iommu]

Hi Dan,

On Thu, Jun 4, 2020 at 7:06 AM Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> On Wed, Jun 03, 2020 at 03:20:41PM -0400, Jim Quinlan wrote:
> > @@ -786,7 +787,7 @@ static int sun4i_backend_bind(struct device *dev, struct device *master,
> >       const struct sun4i_backend_quirks *quirks;
> >       struct resource *res;
> >       void __iomem *regs;
> > -     int i, ret;
> > +     int i, ret = 0;
>
> No need for this.
Will fix.

>
> >
> >       backend = devm_kzalloc(dev, sizeof(*backend), GFP_KERNEL);
> >       if (!backend)
> > @@ -812,7 +813,9 @@ static int sun4i_backend_bind(struct device *dev, struct device *master,
> >                * on our device since the RAM mapping is at 0 for the DMA bus,
> >                * unlike the CPU.
> >                */
> > -             drm->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
> > +             ret = attach_uniform_dma_pfn_offset(dev, PHYS_PFN_OFFSET);
> > +             if (ret)
> > +                     return ret;
> >       }
> >
> >       backend->engine.node = dev->of_node;
> > diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> > index 04fbd4bf0ff9..e9cc1c2d47cd 100644
> > --- a/drivers/iommu/io-pgtable-arm.c
> > +++ b/drivers/iommu/io-pgtable-arm.c
> > @@ -754,7 +754,7 @@ arm_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg)
> >       if (cfg->oas > ARM_LPAE_MAX_ADDR_BITS)
> >               return NULL;
> >
> > -     if (!selftest_running && cfg->iommu_dev->dma_pfn_offset) {
> > +     if (!selftest_running && cfg->iommu_dev->dma_pfn_offset_map) {
> >               dev_err(cfg->iommu_dev, "Cannot accommodate DMA offset for IOMMU page tables\n");
> >               return NULL;
> >       }
> > diff --git a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> > index eff34ded6305..7212da5e1076 100644
> > --- a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> > +++ b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> > @@ -7,6 +7,7 @@
> >   */
> >
> >  #include <linux/clk.h>
> > +#include <linux/dma-mapping.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/module.h>
> >  #include <linux/mutex.h>
> > @@ -183,7 +184,9 @@ static int sun4i_csi_probe(struct platform_device *pdev)
> >                       return ret;
> >       } else {
> >  #ifdef PHYS_PFN_OFFSET
> > -             csi->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
> > +             ret = attach_uniform_dma_pfn_offset(dev, PHYS_PFN_OFFSET);
> > +             if (ret)
> > +                     return ret;
> >  #endif
> >       }
> >
> > diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > index 055eb0b8e396..2d66d415b6c3 100644
> > --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > @@ -898,7 +898,10 @@ static int sun6i_csi_probe(struct platform_device *pdev)
> >
> >       sdev->dev = &pdev->dev;
> >       /* The DMA bus has the memory mapped at 0 */
> > -     sdev->dev->dma_pfn_offset = PHYS_OFFSET >> PAGE_SHIFT;
> > +     ret = attach_uniform_dma_pfn_offset(sdev->dev,
> > +                                         PHYS_OFFSET >> PAGE_SHIFT);
> > +     if (ret)
> > +             return ret;
> >
> >       ret = sun6i_csi_resource_request(sdev, pdev);
> >       if (ret)
> > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > index 96d8cfb14a60..c89333b0a5fb 100644
> > --- a/drivers/of/address.c
> > +++ b/drivers/of/address.c
> > @@ -918,6 +918,70 @@ void __iomem *of_io_request_and_map(struct device_node *np, int index,
> >  }
> >  EXPORT_SYMBOL(of_io_request_and_map);
> >
> > +static int attach_dma_pfn_offset_map(struct device *dev,
> > +                                  struct device_node *node, int num_ranges)
> > +{
> > +     struct of_range_parser parser;
> > +     struct of_range range;
> > +     struct dma_pfn_offset_region *r;
> > +
> > +     r = devm_kcalloc(dev, num_ranges + 1,
> > +                      sizeof(struct dma_pfn_offset_region), GFP_KERNEL);
> > +     if (!r)
> > +             return -ENOMEM;
> > +     dev->dma_pfn_offset_map = r;
> > +     of_dma_range_parser_init(&parser, node);
> > +
> > +     /*
> > +      * Record all info for DMA ranges array.  We could
> > +      * just use the of_range struct, but if we did that it
> > +      * would require more calculations for phys_to_dma and
> > +      * dma_to_phys conversions.
> > +      */
> > +     for_each_of_range(&parser, &range) {
> > +             r->cpu_start = range.cpu_addr;
> > +             r->cpu_end = r->cpu_start + range.size - 1;
> > +             r->dma_start = range.bus_addr;
> > +             r->dma_end = r->dma_start + range.size - 1;
> > +             r->pfn_offset = PFN_DOWN(range.cpu_addr)
> > +                     - PFN_DOWN(range.bus_addr);
> > +             r++;
> > +     }
> > +     return 0;
> > +}
> > +
> > +
> > +
> > +/**
> > + * attach_dma_pfn_offset - Assign scalar offset for all addresses.
> > + * @dev:     device pointer; only needed for a corner case.
> > + * @dma_pfn_offset:  offset to apply when converting from phys addr
>       ^^^^^^^^^^^^^^^
> This parameter name does not match.
Will fix.

>
> > + *                   to dma addr and vice versa.
> > + *
> > + * It returns -ENOMEM if out of memory, otherwise 0.
>
> It can also return -ENODEV.  Why are we passing NULL dev pointers to
> all these functions anyway?
No one should be passing dev==NULL to these functions -- that is why I
have the error out for this case.  Actually, there is a case of
dev==NULL being passed -- drivers/of/unittest.c makes a call with  a
NULL device because it has no dev  in its context.  I wasn't sure how
to fix this.

>
> > + */
> > +int attach_uniform_dma_pfn_offset(struct device *dev, unsigned long pfn_offset)
> > +{
> > +     struct dma_pfn_offset_region *r;
> > +
> > +     if (!dev)
> > +             return -ENODEV;
> > +
> > +     if (!pfn_offset)
> > +             return 0;
> > +
> > +     r = devm_kcalloc(dev, 1, sizeof(struct dma_pfn_offset_region),
> > +                      GFP_KERNEL);
>
> Use:    r = devm_kzalloc(dev, sizeof(*r), GFP_KERNEL);
Will fix.

>
>
> > +     if (!r)
> > +             return -ENOMEM;
> > +
> > +     r->uniform_offset = true;
> > +     r->pfn_offset = pfn_offset;
> > +
> > +     return 0;
> > +}
>
> This function doesn't seem to do anything useful.  Is part of it
> missing?
No, the uniform pfn offset is a special case.  With it, there is only
one entry  in the "map" and 'uniform_offset' is set to true and the
pfn_offset is also set.  When the offset is to be computed, there are
no region bounds calculations needed -- the offset of the first entry
is returned immediately.  This special case was intentional to (a)
preserve backwards compatibility to  those using dev->dma_pfn_offset
and (b) it is faster than treating it as the general case -- I want to
minimize the execution cost of this case.  If this is deemed
unnecessary, I can remove the boolean and threat all cases in the same
way.

The other case is where multiple pfn offsets are needed for multiple
regions.  In this case the code checks the bounds for each successive
region, returning an  offset if there is a match.
>
> > +EXPORT_SYMBOL_GPL(attach_uniform_dma_pfn_offset);
> > +
>
> regards,
> dan carpenter
>

Thanks!
Jim Quinlan
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Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

[Dan Carpenter]

On Thu, Jun 04, 2020 at 09:48:49AM -0400, Jim Quinlan wrote:
> > > +     r = devm_kcalloc(dev, 1, sizeof(struct dma_pfn_offset_region),
> > > +                      GFP_KERNEL);
> >
> > Use:    r = devm_kzalloc(dev, sizeof(*r), GFP_KERNEL);
> Will fix.
> 
> >
> >
> > > +     if (!r)
> > > +             return -ENOMEM;
> > > +
> > > +     r->uniform_offset = true;
> > > +     r->pfn_offset = pfn_offset;
> > > +
> > > +     return 0;
> > > +}
> >
> > This function doesn't seem to do anything useful.  Is part of it
> > missing?
> No, the uniform pfn offset is a special case.

Sorry, I wasn't clear.  We're talking about different things.  The code
does:

	r = devm_kzalloc(dev, sizeof(*r), GFP_KERNEL);
	if (!r)
		return -ENOMEM;

	r->uniform_offset = true;
	r->pfn_offset = pfn_offset;

	return 0;

The code allocates "r" and then doesn't save it anywhere so there is
no point.

regards,
dan carpenter

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Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

[Jim Quinlan via iommu]

On Thu, Jun 4, 2020 at 10:20 AM Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> On Thu, Jun 04, 2020 at 09:48:49AM -0400, Jim Quinlan wrote:
> > > > +     r = devm_kcalloc(dev, 1, sizeof(struct dma_pfn_offset_region),
> > > > +                      GFP_KERNEL);
> > >
> > > Use:    r = devm_kzalloc(dev, sizeof(*r), GFP_KERNEL);
> > Will fix.
> >
> > >
> > >
> > > > +     if (!r)
> > > > +             return -ENOMEM;
> > > > +
> > > > +     r->uniform_offset = true;
> > > > +     r->pfn_offset = pfn_offset;
> > > > +
> > > > +     return 0;
> > > > +}
> > >
> > > This function doesn't seem to do anything useful.  Is part of it
> > > missing?
> > No, the uniform pfn offset is a special case.
>
> Sorry, I wasn't clear.  We're talking about different things.  The code
> does:
>
>         r = devm_kzalloc(dev, sizeof(*r), GFP_KERNEL);
>         if (!r)
>                 return -ENOMEM;
>
>         r->uniform_offset = true;
>         r->pfn_offset = pfn_offset;
>
>         return 0;
>
> The code allocates "r" and then doesn't save it anywhere so there is
> no point.
You are absolutely right, sorry I missed your point.  Will fix.

Thanks,
Jim Quinlan

>
> regards,
> dan carpenter
>
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Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

[Nicolas Saenz Julienne]

[-- Attachment #1.1: Type: text/plain, Size: 15878 bytes --]

Hi Jim,

On Wed, 2020-06-03 at 15:20 -0400, Jim Quinlan wrote:
> The new field in struct device 'dma_pfn_offset_map' is used to facilitate
> the use of multiple pfn offsets between cpu addrs and dma addrs.  It
> subsumes the role of dev->dma_pfn_offset -- a uniform offset -- and
> designates the single offset a special case.
> 
> of_dma_configure() is the typical manner to set pfn offsets but there
> are a number of ad hoc assignments to dev->dma_pfn_offset in the
> kernel code.  These cases now invoke the function
> attach_uniform_dma_pfn_offset(dev, pfn_offset).
> 
> Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
> ---
>  arch/arm/include/asm/dma-mapping.h            |  9 +-
>  arch/arm/mach-keystone/keystone.c             |  9 +-
>  arch/sh/drivers/pci/pcie-sh7786.c             |  3 +-
>  arch/sh/kernel/dma-coherent.c                 | 17 ++--
>  arch/x86/pci/sta2x11-fixup.c                  |  7 +-
>  drivers/acpi/arm64/iort.c                     |  5 +-
>  drivers/gpu/drm/sun4i/sun4i_backend.c         |  7 +-
>  drivers/iommu/io-pgtable-arm.c                |  2 +-
>  .../platform/sunxi/sun4i-csi/sun4i_csi.c      |  5 +-
>  .../platform/sunxi/sun6i-csi/sun6i_csi.c      |  5 +-
>  drivers/of/address.c                          | 93 +++++++++++++++++--
>  drivers/of/device.c                           |  8 +-
>  drivers/remoteproc/remoteproc_core.c          |  2 +-
>  .../staging/media/sunxi/cedrus/cedrus_hw.c    |  7 +-
>  drivers/usb/core/message.c                    |  4 +-
>  drivers/usb/core/usb.c                        |  2 +-
>  include/linux/device.h                        |  4 +-
>  include/linux/dma-direct.h                    | 16 +++-
>  include/linux/dma-mapping.h                   | 45 +++++++++
>  kernel/dma/coherent.c                         | 11 ++-
>  20 files changed, 210 insertions(+), 51 deletions(-)
> 
> diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-
> mapping.h
> index bdd80ddbca34..f1e72f99468b 100644
> --- a/arch/arm/include/asm/dma-mapping.h
> +++ b/arch/arm/include/asm/dma-mapping.h
> @@ -35,8 +35,9 @@ static inline const struct dma_map_ops
> *get_arch_dma_ops(struct bus_type *bus)
>  #ifndef __arch_pfn_to_dma
>  static inline dma_addr_t pfn_to_dma(struct device *dev, unsigned long pfn)
>  {
> -	if (dev)
> -		pfn -= dev->dma_pfn_offset;
> +	if (dev && dev->dma_pfn_offset_map)

Would it make sense to move the dev->dma_pfn_offset_map check into
dma_pfn_offset_from_phys_addr() and return 0 if not available? Same for the
opposite variant of the function. I think it'd make the code a little simpler on
some of the use cases, and overall less error prone if anyone starts using the
function elsewhere.

> +		pfn -= dma_pfn_offset_from_phys_addr(dev, PFN_PHYS(pfn));
> +
>  	return (dma_addr_t)__pfn_to_bus(pfn);
>  }
>  
> @@ -44,8 +45,8 @@ static inline unsigned long dma_to_pfn(struct device *dev,
> dma_addr_t addr)
>  {
>  	unsigned long pfn = __bus_to_pfn(addr);
>  
> -	if (dev)
> -		pfn += dev->dma_pfn_offset;
> +	if (dev && dev->dma_pfn_offset_map)
> +		pfn += dma_pfn_offset_from_dma_addr(dev, addr);
>  
>  	return pfn;
>  }
> diff --git a/arch/arm/mach-keystone/keystone.c b/arch/arm/mach-
> keystone/keystone.c
> index 638808c4e122..e7d3ee6e9cb5 100644
> --- a/arch/arm/mach-keystone/keystone.c
> +++ b/arch/arm/mach-keystone/keystone.c
> @@ -8,6 +8,7 @@
>   */
>  #include <linux/io.h>
>  #include <linux/of.h>
> +#include <linux/dma-mapping.h>
>  #include <linux/init.h>
>  #include <linux/of_platform.h>
>  #include <linux/of_address.h>
> @@ -38,9 +39,11 @@ static int keystone_platform_notifier(struct notifier_block
> *nb,
>  		return NOTIFY_BAD;
>  
>  	if (!dev->of_node) {
> -		dev->dma_pfn_offset = keystone_dma_pfn_offset;
> -		dev_err(dev, "set dma_pfn_offset%08lx\n",
> -			dev->dma_pfn_offset);
> +		int ret = attach_uniform_dma_pfn_offset
> +				(dev, keystone_dma_pfn_offset);
> +
> +		dev_err(dev, "set dma_pfn_offset%08lx%s\n",
> +			dev->dma_pfn_offset, ret ? " failed" : "");
>  	}
>  	return NOTIFY_OK;
>  }
> diff --git a/arch/sh/drivers/pci/pcie-sh7786.c b/arch/sh/drivers/pci/pcie-
> sh7786.c
> index e0b568aaa701..2e832a5c58c1 100644
> --- a/arch/sh/drivers/pci/pcie-sh7786.c
> +++ b/arch/sh/drivers/pci/pcie-sh7786.c
> @@ -12,6 +12,7 @@
>  #include <linux/io.h>
>  #include <linux/async.h>
>  #include <linux/delay.h>
> +#include <linux/dma-mapping.h>
>  #include <linux/slab.h>
>  #include <linux/clk.h>
>  #include <linux/sh_clk.h>
> @@ -487,7 +488,7 @@ int pcibios_map_platform_irq(const struct pci_dev *pdev,
> u8 slot, u8 pin)
>  
>  void pcibios_bus_add_device(struct pci_dev *pdev)
>  {
> -	pdev->dev.dma_pfn_offset = dma_pfn_offset;
> +	attach_uniform_dma_pfn_offset(&pdev->dev, dma_pfn_offset);
>  }
>  
>  static int __init sh7786_pcie_core_init(void)
> diff --git a/arch/sh/kernel/dma-coherent.c b/arch/sh/kernel/dma-coherent.c
> index d4811691b93c..5fc9e358b6c7 100644
> --- a/arch/sh/kernel/dma-coherent.c
> +++ b/arch/sh/kernel/dma-coherent.c
> @@ -14,6 +14,8 @@ void *arch_dma_alloc(struct device *dev, size_t size,
> dma_addr_t *dma_handle,
>  {
>  	void *ret, *ret_nocache;
>  	int order = get_order(size);
> +	unsigned long pfn;
> +	phys_addr_t phys;
>  
>  	gfp |= __GFP_ZERO;
>  
> @@ -34,11 +36,14 @@ void *arch_dma_alloc(struct device *dev, size_t size,
> dma_addr_t *dma_handle,
>  		return NULL;
>  	}
>  
> -	split_page(pfn_to_page(virt_to_phys(ret) >> PAGE_SHIFT), order);
> +	phys = virt_to_phys(ret);
> +	pfn =  phys >> PAGE_SHIFT;

nit: not sure it really pays off to have a pfn variable here.

> +	split_page(pfn_to_page(pfn), order);
>  
> -	*dma_handle = virt_to_phys(ret);
> -	if (!WARN_ON(!dev))
> -		*dma_handle -= PFN_PHYS(dev->dma_pfn_offset);
> +	*dma_handle = (dma_addr_t)phys;
> +	if (!WARN_ON(!dev) && dev->dma_pfn_offset_map)
> +		*dma_handle -= PFN_PHYS(
> +			dma_pfn_offset_from_phys_addr(dev, phys));

>  
>  	return ret_nocache;
>  }
> @@ -50,8 +55,8 @@ void arch_dma_free(struct device *dev, size_t size, void
> *vaddr,
>  	unsigned long pfn = (dma_handle >> PAGE_SHIFT);
>  	int k;
>  
> -	if (!WARN_ON(!dev))
> -		pfn += dev->dma_pfn_offset;
> +	if (!WARN_ON(!dev) && dev->dma_pfn_offset_map)
> +		pfn += dma_pfn_offset_from_dma_addr(dev, dma_handle);
>  
>  	for (k = 0; k < (1 << order); k++)
>  		__free_pages(pfn_to_page(pfn + k), 0);
> diff --git a/arch/x86/pci/sta2x11-fixup.c b/arch/x86/pci/sta2x11-fixup.c
> index c313d784efab..4cdeca9f69b6 100644
> --- a/arch/x86/pci/sta2x11-fixup.c
> +++ b/arch/x86/pci/sta2x11-fixup.c
> @@ -12,6 +12,7 @@
>  #include <linux/export.h>
>  #include <linux/list.h>
>  #include <linux/dma-direct.h>
> +#include <linux/dma-mapping.h>
>  #include <asm/iommu.h>
>  
>  #define STA2X11_SWIOTLB_SIZE (4*1024*1024)
> @@ -133,7 +134,7 @@ static void sta2x11_map_ep(struct pci_dev *pdev)
>  	struct sta2x11_instance *instance = sta2x11_pdev_to_instance(pdev);
>  	struct device *dev = &pdev->dev;
>  	u32 amba_base, max_amba_addr;
> -	int i;
> +	int i, ret;
>  
>  	if (!instance)
>  		return;
> @@ -141,7 +142,9 @@ static void sta2x11_map_ep(struct pci_dev *pdev)
>  	pci_read_config_dword(pdev, AHB_BASE(0), &amba_base);
>  	max_amba_addr = amba_base + STA2X11_AMBA_SIZE - 1;
>  
> -	dev->dma_pfn_offset = PFN_DOWN(-amba_base);
> +	ret = attach_uniform_dma_pfn_offset(dev, PFN_DOWN(-amba_base));
> +	if (ret)
> +		dev_err(dev, "sta2x11: could not set PFN offset\n");
>  
>  	dev->bus_dma_limit = max_amba_addr;
>  	pci_set_consistent_dma_mask(pdev, max_amba_addr);
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 28a6b387e80e..153661ddc74b 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -1142,8 +1142,9 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr,
> u64 *dma_size)
>  	*dma_addr = dmaaddr;
>  	*dma_size = size;
>  
> -	dev->dma_pfn_offset = PFN_DOWN(offset);
> -	dev_dbg(dev, "dma_pfn_offset(%#08llx)\n", offset);
> +	ret = attach_uniform_dma_pfn_offset(dev, PFN_DOWN(offset));
> +	dev_dbg(dev, "dma_pfn_offset(%#08llx)%s\n",
> +		offset, ret ? " failed!" : "");
>  }
>  
>  static void __init acpi_iort_register_irq(int hwirq, const char *name,
> diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c
> b/drivers/gpu/drm/sun4i/sun4i_backend.c
> index 072ea113e6be..3d41dfc7d178 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_backend.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_backend.c
> @@ -11,6 +11,7 @@
>  #include <linux/module.h>
>  #include <linux/of_device.h>
>  #include <linux/of_graph.h>
> +#include <linux/dma-mapping.h>
>  #include <linux/platform_device.h>
>  #include <linux/reset.h>
>  
> @@ -786,7 +787,7 @@ static int sun4i_backend_bind(struct device *dev, struct
> device *master,
>  	const struct sun4i_backend_quirks *quirks;
>  	struct resource *res;
>  	void __iomem *regs;
> -	int i, ret;
> +	int i, ret = 0;
>  
>  	backend = devm_kzalloc(dev, sizeof(*backend), GFP_KERNEL);
>  	if (!backend)
> @@ -812,7 +813,9 @@ static int sun4i_backend_bind(struct device *dev, struct
> device *master,
>  		 * on our device since the RAM mapping is at 0 for the DMA bus,
>  		 * unlike the CPU.
>  		 */
> -		drm->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
> +		ret = attach_uniform_dma_pfn_offset(dev, PHYS_PFN_OFFSET);
> +		if (ret)
> +			return ret;
>  	}
>  
>  	backend->engine.node = dev->of_node;
> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index 04fbd4bf0ff9..e9cc1c2d47cd 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -754,7 +754,7 @@ arm_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg)
>  	if (cfg->oas > ARM_LPAE_MAX_ADDR_BITS)
>  		return NULL;
>  
> -	if (!selftest_running && cfg->iommu_dev->dma_pfn_offset) {
> +	if (!selftest_running && cfg->iommu_dev->dma_pfn_offset_map) {
>  		dev_err(cfg->iommu_dev, "Cannot accommodate DMA offset for IOMMU
> page tables\n");
>  		return NULL;
>  	}
> diff --git a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> index eff34ded6305..7212da5e1076 100644
> --- a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> +++ b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> @@ -7,6 +7,7 @@
>   */
>  
>  #include <linux/clk.h>
> +#include <linux/dma-mapping.h>
>  #include <linux/interrupt.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
> @@ -183,7 +184,9 @@ static int sun4i_csi_probe(struct platform_device *pdev)
>  			return ret;
>  	} else {
>  #ifdef PHYS_PFN_OFFSET
> -		csi->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
> +		ret = attach_uniform_dma_pfn_offset(dev, PHYS_PFN_OFFSET);
> +		if (ret)
> +			return ret;
>  #endif
>  	}
>  
> diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> index 055eb0b8e396..2d66d415b6c3 100644
> --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> @@ -898,7 +898,10 @@ static int sun6i_csi_probe(struct platform_device *pdev)
>  
>  	sdev->dev = &pdev->dev;
>  	/* The DMA bus has the memory mapped at 0 */
> -	sdev->dev->dma_pfn_offset = PHYS_OFFSET >> PAGE_SHIFT;
> +	ret = attach_uniform_dma_pfn_offset(sdev->dev,
> +					    PHYS_OFFSET >> PAGE_SHIFT);
> +	if (ret)
> +		return ret;
>  
>  	ret = sun6i_csi_resource_request(sdev, pdev);
>  	if (ret)
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index 96d8cfb14a60..c89333b0a5fb 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -918,6 +918,70 @@ void __iomem *of_io_request_and_map(struct device_node
> *np, int index,
>  }
>  EXPORT_SYMBOL(of_io_request_and_map);
>  
> +static int attach_dma_pfn_offset_map(struct device *dev,
> +				     struct device_node *node, int num_ranges)

As with the previous review, please take this comment with a grain of salt.

I think there should be a clear split between what belongs to OF and what
belongs to the core device infrastructure.

OF's job should be to parse DT and provide a list/array of ranges, whereas the
core device infrastructure should provide an API to assign a list of
ranges/offset to a device.

As a concrete example, you're forcing devices like the sta2x11 to build with OF
support, which, being an Intel device, it's pretty odd. But I'm also thinking
of how will all this fit once an ACPI device wants to use it.

Expanding on this idea, once you have a split between the OF's and device core
roles, it transpires that of_dma_get_range()'s job should only be to provide
the ranges in a device understandable structure and of_dma_configre()'s to
actually assign the device's parameters. This would obsolete patch #7.

> +{
> +	struct of_range_parser parser;
> +	struct of_range range;
> +	struct dma_pfn_offset_region *r;
> +
> +	r = devm_kcalloc(dev, num_ranges + 1,
> +			 sizeof(struct dma_pfn_offset_region), GFP_KERNEL);
> +	if (!r)
> +		return -ENOMEM;
> +	dev->dma_pfn_offset_map = r;
> +	of_dma_range_parser_init(&parser, node);
> +
> +	/*
> +	 * Record all info for DMA ranges array.  We could
> +	 * just use the of_range struct, but if we did that it
> +	 * would require more calculations for phys_to_dma and
> +	 * dma_to_phys conversions.
> +	 */
> +	for_each_of_range(&parser, &range) {
> +		r->cpu_start = range.cpu_addr;
> +		r->cpu_end = r->cpu_start + range.size - 1;
> +		r->dma_start = range.bus_addr;
> +		r->dma_end = r->dma_start + range.size - 1;
> +		r->pfn_offset = PFN_DOWN(range.cpu_addr)
> +			- PFN_DOWN(range.bus_addr);
> +		r++;
> +	}
> +	return 0;
> +}
> +
> +
> +
> +/**
> + * attach_dma_pfn_offset - Assign scalar offset for all addresses.
> + * @dev:	device pointer; only needed for a corner case.

That's a huge corner :P

> + * @dma_pfn_offset:	offset to apply when converting from phys addr
> + *			to dma addr and vice versa.
> + *
> + * It returns -ENOMEM if out of memory, otherwise 0.
> + */
> +int attach_uniform_dma_pfn_offset(struct device *dev, unsigned long
> pfn_offset)

As I say above, does this really belong to of/address.c?

> +{
> +	struct dma_pfn_offset_region *r;
> +
> +	if (!dev)
> +		return -ENODEV;
> +
> +	if (!pfn_offset)
> +		return 0;
> +
> +	r = devm_kcalloc(dev, 1, sizeof(struct dma_pfn_offset_region),
> +			 GFP_KERNEL);
> +	if (!r)
> +		return -ENOMEM;

I think you're missing this:

	dev->dma_pfn_offset_map = r;

> +
> +	r->uniform_offset = true;
> +	r->pfn_offset = pfn_offset;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(attach_uniform_dma_pfn_offset);
> +
>  /**
>   * of_dma_get_range - Get DMA range info
>   * @dev:	device pointer; only needed for a corner case.
> @@ -933,7 +997,7 @@ EXPORT_SYMBOL(of_io_request_and_map);
>   *	CPU addr (phys_addr_t)	: pna cells
>   *	size			: nsize cells
>   *
> - * It returns -ENODEV if "dma-ranges" property was not found
> + * It returns -ENODEV if !dev or "dma-ranges" property was not found
>   * for this device in DT.
>   */
>  int of_dma_get_range(struct device *dev, struct device_node *np, u64
> *dma_addr,
> @@ -946,7 +1010,13 @@ int of_dma_get_range(struct device *dev, struct
> device_node *np, u64 *dma_addr,
>  	bool found_dma_ranges = false;
>  	struct of_range_parser parser;
>  	struct of_range range;
> +	phys_addr_t cpu_start = ~(phys_addr_t)0;
>  	u64 dma_start = U64_MAX, dma_end = 0, dma_offset = 0;
> +	bool dma_multi_pfn_offset = false;
> +	int num_ranges = 0;
> +
> +	if (!dev)
> +		return -ENODEV;

Shouldn't this be part of patch #7?

Regards,
Nicolas


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Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

[Jim Quinlan via iommu]

On Thu, Jun 4, 2020 at 9:53 AM Nicolas Saenz Julienne
<nsaenzjulienne@suse.de> wrote:
>
> Hi Jim,
>
> On Wed, 2020-06-03 at 15:20 -0400, Jim Quinlan wrote:
> > The new field in struct device 'dma_pfn_offset_map' is used to facilitate
> > the use of multiple pfn offsets between cpu addrs and dma addrs.  It
> > subsumes the role of dev->dma_pfn_offset -- a uniform offset -- and
> > designates the single offset a special case.
> >
> > of_dma_configure() is the typical manner to set pfn offsets but there
> > are a number of ad hoc assignments to dev->dma_pfn_offset in the
> > kernel code.  These cases now invoke the function
> > attach_uniform_dma_pfn_offset(dev, pfn_offset).
> >
> > Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
> > ---
> >  arch/arm/include/asm/dma-mapping.h            |  9 +-
> >  arch/arm/mach-keystone/keystone.c             |  9 +-
> >  arch/sh/drivers/pci/pcie-sh7786.c             |  3 +-
> >  arch/sh/kernel/dma-coherent.c                 | 17 ++--
> >  arch/x86/pci/sta2x11-fixup.c                  |  7 +-
> >  drivers/acpi/arm64/iort.c                     |  5 +-
> >  drivers/gpu/drm/sun4i/sun4i_backend.c         |  7 +-
> >  drivers/iommu/io-pgtable-arm.c                |  2 +-
> >  .../platform/sunxi/sun4i-csi/sun4i_csi.c      |  5 +-
> >  .../platform/sunxi/sun6i-csi/sun6i_csi.c      |  5 +-
> >  drivers/of/address.c                          | 93 +++++++++++++++++--
> >  drivers/of/device.c                           |  8 +-
> >  drivers/remoteproc/remoteproc_core.c          |  2 +-
> >  .../staging/media/sunxi/cedrus/cedrus_hw.c    |  7 +-
> >  drivers/usb/core/message.c                    |  4 +-
> >  drivers/usb/core/usb.c                        |  2 +-
> >  include/linux/device.h                        |  4 +-
> >  include/linux/dma-direct.h                    | 16 +++-
> >  include/linux/dma-mapping.h                   | 45 +++++++++
> >  kernel/dma/coherent.c                         | 11 ++-
> >  20 files changed, 210 insertions(+), 51 deletions(-)
> >
> > diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-
> > mapping.h
> > index bdd80ddbca34..f1e72f99468b 100644
> > --- a/arch/arm/include/asm/dma-mapping.h
> > +++ b/arch/arm/include/asm/dma-mapping.h
> > @@ -35,8 +35,9 @@ static inline const struct dma_map_ops
> > *get_arch_dma_ops(struct bus_type *bus)
> >  #ifndef __arch_pfn_to_dma
> >  static inline dma_addr_t pfn_to_dma(struct device *dev, unsigned long pfn)
> >  {
> > -     if (dev)
> > -             pfn -= dev->dma_pfn_offset;
> > +     if (dev && dev->dma_pfn_offset_map)
>
> Would it make sense to move the dev->dma_pfn_offset_map check into
> dma_pfn_offset_from_phys_addr() and return 0 if not available? Same for the
> opposite variant of the function. I think it'd make the code a little simpler on
> some of the use cases, and overall less error prone if anyone starts using the
> function elsewhere.

Yes it makes sense and I was debating doing it but I just wanted to
make it explicit that there was not much cost for this change for the
fastpath -- no dma_pfn_offset whatsoever -- as the cost goes from a
"pfn += dev->dma_pfn_offset"  to a "if (dev->dma_pfn_offset_map)".  I
will do what you suggest.
>
> > +             pfn -= dma_pfn_offset_from_phys_addr(dev, PFN_PHYS(pfn));
> > +
> >       return (dma_addr_t)__pfn_to_bus(pfn);
> >  }
> >
> > @@ -44,8 +45,8 @@ static inline unsigned long dma_to_pfn(struct device *dev,
> > dma_addr_t addr)
> >  {
> >       unsigned long pfn = __bus_to_pfn(addr);
> >
> > -     if (dev)
> > -             pfn += dev->dma_pfn_offset;
> > +     if (dev && dev->dma_pfn_offset_map)
> > +             pfn += dma_pfn_offset_from_dma_addr(dev, addr);
> >
> >       return pfn;
> >  }
> > diff --git a/arch/arm/mach-keystone/keystone.c b/arch/arm/mach-
> > keystone/keystone.c
> > index 638808c4e122..e7d3ee6e9cb5 100644
> > --- a/arch/arm/mach-keystone/keystone.c
> > +++ b/arch/arm/mach-keystone/keystone.c
> > @@ -8,6 +8,7 @@
> >   */
> >  #include <linux/io.h>
> >  #include <linux/of.h>
> > +#include <linux/dma-mapping.h>
> >  #include <linux/init.h>
> >  #include <linux/of_platform.h>
> >  #include <linux/of_address.h>
> > @@ -38,9 +39,11 @@ static int keystone_platform_notifier(struct notifier_block
> > *nb,
> >               return NOTIFY_BAD;
> >
> >       if (!dev->of_node) {
> > -             dev->dma_pfn_offset = keystone_dma_pfn_offset;
> > -             dev_err(dev, "set dma_pfn_offset%08lx\n",
> > -                     dev->dma_pfn_offset);
> > +             int ret = attach_uniform_dma_pfn_offset
> > +                             (dev, keystone_dma_pfn_offset);
> > +
> > +             dev_err(dev, "set dma_pfn_offset%08lx%s\n",
> > +                     dev->dma_pfn_offset, ret ? " failed" : "");
> >       }
> >       return NOTIFY_OK;
> >  }
> > diff --git a/arch/sh/drivers/pci/pcie-sh7786.c b/arch/sh/drivers/pci/pcie-
> > sh7786.c
> > index e0b568aaa701..2e832a5c58c1 100644
> > --- a/arch/sh/drivers/pci/pcie-sh7786.c
> > +++ b/arch/sh/drivers/pci/pcie-sh7786.c
> > @@ -12,6 +12,7 @@
> >  #include <linux/io.h>
> >  #include <linux/async.h>
> >  #include <linux/delay.h>
> > +#include <linux/dma-mapping.h>
> >  #include <linux/slab.h>
> >  #include <linux/clk.h>
> >  #include <linux/sh_clk.h>
> > @@ -487,7 +488,7 @@ int pcibios_map_platform_irq(const struct pci_dev *pdev,
> > u8 slot, u8 pin)
> >
> >  void pcibios_bus_add_device(struct pci_dev *pdev)
> >  {
> > -     pdev->dev.dma_pfn_offset = dma_pfn_offset;
> > +     attach_uniform_dma_pfn_offset(&pdev->dev, dma_pfn_offset);
> >  }
> >
> >  static int __init sh7786_pcie_core_init(void)
> > diff --git a/arch/sh/kernel/dma-coherent.c b/arch/sh/kernel/dma-coherent.c
> > index d4811691b93c..5fc9e358b6c7 100644
> > --- a/arch/sh/kernel/dma-coherent.c
> > +++ b/arch/sh/kernel/dma-coherent.c
> > @@ -14,6 +14,8 @@ void *arch_dma_alloc(struct device *dev, size_t size,
> > dma_addr_t *dma_handle,
> >  {
> >       void *ret, *ret_nocache;
> >       int order = get_order(size);
> > +     unsigned long pfn;
> > +     phys_addr_t phys;
> >
> >       gfp |= __GFP_ZERO;
> >
> > @@ -34,11 +36,14 @@ void *arch_dma_alloc(struct device *dev, size_t size,
> > dma_addr_t *dma_handle,
> >               return NULL;
> >       }
> >
> > -     split_page(pfn_to_page(virt_to_phys(ret) >> PAGE_SHIFT), order);
> > +     phys = virt_to_phys(ret);
> > +     pfn =  phys >> PAGE_SHIFT;
>
> nit: not sure it really pays off to have a pfn variable here.
Did it for readability; the compiler's optimization should take care
of any extra variables.  But I can switch if you insist.
>
> > +     split_page(pfn_to_page(pfn), order);
> >
> > -     *dma_handle = virt_to_phys(ret);
> > -     if (!WARN_ON(!dev))
> > -             *dma_handle -= PFN_PHYS(dev->dma_pfn_offset);
> > +     *dma_handle = (dma_addr_t)phys;
> > +     if (!WARN_ON(!dev) && dev->dma_pfn_offset_map)
> > +             *dma_handle -= PFN_PHYS(
> > +                     dma_pfn_offset_from_phys_addr(dev, phys));
>
> >
> >       return ret_nocache;
> >  }
> > @@ -50,8 +55,8 @@ void arch_dma_free(struct device *dev, size_t size, void
> > *vaddr,
> >       unsigned long pfn = (dma_handle >> PAGE_SHIFT);
> >       int k;
> >
> > -     if (!WARN_ON(!dev))
> > -             pfn += dev->dma_pfn_offset;
> > +     if (!WARN_ON(!dev) && dev->dma_pfn_offset_map)
> > +             pfn += dma_pfn_offset_from_dma_addr(dev, dma_handle);
> >
> >       for (k = 0; k < (1 << order); k++)
> >               __free_pages(pfn_to_page(pfn + k), 0);
> > diff --git a/arch/x86/pci/sta2x11-fixup.c b/arch/x86/pci/sta2x11-fixup.c
> > index c313d784efab..4cdeca9f69b6 100644
> > --- a/arch/x86/pci/sta2x11-fixup.c
> > +++ b/arch/x86/pci/sta2x11-fixup.c
> > @@ -12,6 +12,7 @@
> >  #include <linux/export.h>
> >  #include <linux/list.h>
> >  #include <linux/dma-direct.h>
> > +#include <linux/dma-mapping.h>
> >  #include <asm/iommu.h>
> >
> >  #define STA2X11_SWIOTLB_SIZE (4*1024*1024)
> > @@ -133,7 +134,7 @@ static void sta2x11_map_ep(struct pci_dev *pdev)
> >       struct sta2x11_instance *instance = sta2x11_pdev_to_instance(pdev);
> >       struct device *dev = &pdev->dev;
> >       u32 amba_base, max_amba_addr;
> > -     int i;
> > +     int i, ret;
> >
> >       if (!instance)
> >               return;
> > @@ -141,7 +142,9 @@ static void sta2x11_map_ep(struct pci_dev *pdev)
> >       pci_read_config_dword(pdev, AHB_BASE(0), &amba_base);
> >       max_amba_addr = amba_base + STA2X11_AMBA_SIZE - 1;
> >
> > -     dev->dma_pfn_offset = PFN_DOWN(-amba_base);
> > +     ret = attach_uniform_dma_pfn_offset(dev, PFN_DOWN(-amba_base));
> > +     if (ret)
> > +             dev_err(dev, "sta2x11: could not set PFN offset\n");
> >
> >       dev->bus_dma_limit = max_amba_addr;
> >       pci_set_consistent_dma_mask(pdev, max_amba_addr);
> > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> > index 28a6b387e80e..153661ddc74b 100644
> > --- a/drivers/acpi/arm64/iort.c
> > +++ b/drivers/acpi/arm64/iort.c
> > @@ -1142,8 +1142,9 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr,
> > u64 *dma_size)
> >       *dma_addr = dmaaddr;
> >       *dma_size = size;
> >
> > -     dev->dma_pfn_offset = PFN_DOWN(offset);
> > -     dev_dbg(dev, "dma_pfn_offset(%#08llx)\n", offset);
> > +     ret = attach_uniform_dma_pfn_offset(dev, PFN_DOWN(offset));
> > +     dev_dbg(dev, "dma_pfn_offset(%#08llx)%s\n",
> > +             offset, ret ? " failed!" : "");
> >  }
> >
> >  static void __init acpi_iort_register_irq(int hwirq, const char *name,
> > diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c
> > b/drivers/gpu/drm/sun4i/sun4i_backend.c
> > index 072ea113e6be..3d41dfc7d178 100644
> > --- a/drivers/gpu/drm/sun4i/sun4i_backend.c
> > +++ b/drivers/gpu/drm/sun4i/sun4i_backend.c
> > @@ -11,6 +11,7 @@
> >  #include <linux/module.h>
> >  #include <linux/of_device.h>
> >  #include <linux/of_graph.h>
> > +#include <linux/dma-mapping.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/reset.h>
> >
> > @@ -786,7 +787,7 @@ static int sun4i_backend_bind(struct device *dev, struct
> > device *master,
> >       const struct sun4i_backend_quirks *quirks;
> >       struct resource *res;
> >       void __iomem *regs;
> > -     int i, ret;
> > +     int i, ret = 0;
> >
> >       backend = devm_kzalloc(dev, sizeof(*backend), GFP_KERNEL);
> >       if (!backend)
> > @@ -812,7 +813,9 @@ static int sun4i_backend_bind(struct device *dev, struct
> > device *master,
> >                * on our device since the RAM mapping is at 0 for the DMA bus,
> >                * unlike the CPU.
> >                */
> > -             drm->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
> > +             ret = attach_uniform_dma_pfn_offset(dev, PHYS_PFN_OFFSET);
> > +             if (ret)
> > +                     return ret;
> >       }
> >
> >       backend->engine.node = dev->of_node;
> > diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> > index 04fbd4bf0ff9..e9cc1c2d47cd 100644
> > --- a/drivers/iommu/io-pgtable-arm.c
> > +++ b/drivers/iommu/io-pgtable-arm.c
> > @@ -754,7 +754,7 @@ arm_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg)
> >       if (cfg->oas > ARM_LPAE_MAX_ADDR_BITS)
> >               return NULL;
> >
> > -     if (!selftest_running && cfg->iommu_dev->dma_pfn_offset) {
> > +     if (!selftest_running && cfg->iommu_dev->dma_pfn_offset_map) {
> >               dev_err(cfg->iommu_dev, "Cannot accommodate DMA offset for IOMMU
> > page tables\n");
> >               return NULL;
> >       }
> > diff --git a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> > b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> > index eff34ded6305..7212da5e1076 100644
> > --- a/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> > +++ b/drivers/media/platform/sunxi/sun4i-csi/sun4i_csi.c
> > @@ -7,6 +7,7 @@
> >   */
> >
> >  #include <linux/clk.h>
> > +#include <linux/dma-mapping.h>
> >  #include <linux/interrupt.h>
> >  #include <linux/module.h>
> >  #include <linux/mutex.h>
> > @@ -183,7 +184,9 @@ static int sun4i_csi_probe(struct platform_device *pdev)
> >                       return ret;
> >       } else {
> >  #ifdef PHYS_PFN_OFFSET
> > -             csi->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
> > +             ret = attach_uniform_dma_pfn_offset(dev, PHYS_PFN_OFFSET);
> > +             if (ret)
> > +                     return ret;
> >  #endif
> >       }
> >
> > diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > index 055eb0b8e396..2d66d415b6c3 100644
> > --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > @@ -898,7 +898,10 @@ static int sun6i_csi_probe(struct platform_device *pdev)
> >
> >       sdev->dev = &pdev->dev;
> >       /* The DMA bus has the memory mapped at 0 */
> > -     sdev->dev->dma_pfn_offset = PHYS_OFFSET >> PAGE_SHIFT;
> > +     ret = attach_uniform_dma_pfn_offset(sdev->dev,
> > +                                         PHYS_OFFSET >> PAGE_SHIFT);
> > +     if (ret)
> > +             return ret;
> >
> >       ret = sun6i_csi_resource_request(sdev, pdev);
> >       if (ret)
> > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > index 96d8cfb14a60..c89333b0a5fb 100644
> > --- a/drivers/of/address.c
> > +++ b/drivers/of/address.c
> > @@ -918,6 +918,70 @@ void __iomem *of_io_request_and_map(struct device_node
> > *np, int index,
> >  }
> >  EXPORT_SYMBOL(of_io_request_and_map);
> >
> > +static int attach_dma_pfn_offset_map(struct device *dev,
> > +                                  struct device_node *node, int num_ranges)
>
> As with the previous review, please take this comment with a grain of salt.
>
> I think there should be a clear split between what belongs to OF and what
> belongs to the core device infrastructure.
>
> OF's job should be to parse DT and provide a list/array of ranges, whereas the
> core device infrastructure should provide an API to assign a list of
> ranges/offset to a device.
>
> As a concrete example, you're forcing devices like the sta2x11 to build with OF
> support, which, being an Intel device, it's pretty odd. But I'm also thinking
> of how will all this fit once an ACPI device wants to use it.
To fix this I only have to move attach_uniform_dma_pfn_offset() from
of/address.c to say include/linux/dma-mapping.h.  It has no
dependencies on OF.  Do you agree?

>
> Expanding on this idea, once you have a split between the OF's and device core
> roles, it transpires that of_dma_get_range()'s job should only be to provide
> the ranges in a device understandable structure and of_dma_configre()'s to
> actually assign the device's parameters. This would obsolete patch #7.

I think you mean patch #8.  I agree with you.  The reason I needed a
"struct device *"  in the call is because I wanted to make sure the
memory that is alloc'd belongs to the device that needs it.  If I do a
regular kzalloc(), this memory  will become a leak once someone starts
unbinding/binding their device.  Also, in  all uses of of_dma_rtange()
-- there is only one --  a dev is required as one can't attach an
offset map to NULL.

I do see that there are a number of functions in drivers/of/*.c that
take 'struct device *dev' as an argument so there is precedent for
something like this.  Regardless, I need an owner to the memory I
alloc().


>
> > +{
> > +     struct of_range_parser parser;
> > +     struct of_range range;
> > +     struct dma_pfn_offset_region *r;
> > +
> > +     r = devm_kcalloc(dev, num_ranges + 1,
> > +                      sizeof(struct dma_pfn_offset_region), GFP_KERNEL);
> > +     if (!r)
> > +             return -ENOMEM;
> > +     dev->dma_pfn_offset_map = r;
> > +     of_dma_range_parser_init(&parser, node);
> > +
> > +     /*
> > +      * Record all info for DMA ranges array.  We could
> > +      * just use the of_range struct, but if we did that it
> > +      * would require more calculations for phys_to_dma and
> > +      * dma_to_phys conversions.
> > +      */
> > +     for_each_of_range(&parser, &range) {
> > +             r->cpu_start = range.cpu_addr;
> > +             r->cpu_end = r->cpu_start + range.size - 1;
> > +             r->dma_start = range.bus_addr;
> > +             r->dma_end = r->dma_start + range.size - 1;
> > +             r->pfn_offset = PFN_DOWN(range.cpu_addr)
> > +                     - PFN_DOWN(range.bus_addr);
> > +             r++;
> > +     }
> > +     return 0;
> > +}
> > +
> > +
> > +
> > +/**
> > + * attach_dma_pfn_offset - Assign scalar offset for all addresses.
> > + * @dev:     device pointer; only needed for a corner case.
>
> That's a huge corner :P
Good point; I'm not really sure what percent of Linux configurations
require a dma_pfn_offset.  I'll drop the "corner".

>
> > + * @dma_pfn_offset:  offset to apply when converting from phys addr
> > + *                   to dma addr and vice versa.
> > + *
> > + * It returns -ENOMEM if out of memory, otherwise 0.
> > + */
> > +int attach_uniform_dma_pfn_offset(struct device *dev, unsigned long
> > pfn_offset)
>
> As I say above, does this really belong to of/address.c?
No it does not.  Will fix.

>
> > +{
> > +     struct dma_pfn_offset_region *r;
> > +
> > +     if (!dev)
> > +             return -ENODEV;
> > +
> > +     if (!pfn_offset)
> > +             return 0;
> > +
> > +     r = devm_kcalloc(dev, 1, sizeof(struct dma_pfn_offset_region),
> > +                      GFP_KERNEL);
> > +     if (!r)
> > +             return -ENOMEM;
>
> I think you're missing this:
>
>         dev->dma_pfn_offset_map = r;
>
That's a showstopper!  DanC also pointed it out but I still didn't see
it.  Thanks!

> > +
> > +     r->uniform_offset = true;
> > +     r->pfn_offset = pfn_offset;
> > +
> > +     return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(attach_uniform_dma_pfn_offset);
> > +
> >  /**
> >   * of_dma_get_range - Get DMA range info
> >   * @dev:     device pointer; only needed for a corner case.
> > @@ -933,7 +997,7 @@ EXPORT_SYMBOL(of_io_request_and_map);
> >   *   CPU addr (phys_addr_t)  : pna cells
> >   *   size                    : nsize cells
> >   *
> > - * It returns -ENODEV if "dma-ranges" property was not found
> > + * It returns -ENODEV if !dev or "dma-ranges" property was not found
> >   * for this device in DT.
> >   */
> >  int of_dma_get_range(struct device *dev, struct device_node *np, u64
> > *dma_addr,
> > @@ -946,7 +1010,13 @@ int of_dma_get_range(struct device *dev, struct
> > device_node *np, u64 *dma_addr,
> >       bool found_dma_ranges = false;
> >       struct of_range_parser parser;
> >       struct of_range range;
> > +     phys_addr_t cpu_start = ~(phys_addr_t)0;
> >       u64 dma_start = U64_MAX, dma_end = 0, dma_offset = 0;
> > +     bool dma_multi_pfn_offset = false;
> > +     int num_ranges = 0;
> > +
> > +     if (!dev)
> > +             return -ENODEV;
>
> Shouldn't this be part of patch #7?
Do you mean #8?  Do you mean the test for !dev?   It is not required
for #8 so I thought I'd keep these two changes separate.  I could
squash them.
>
> Regards,
> Nicolas
>
Many thanks!

Jim Quinlan
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Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

[Andy Shevchenko]

On Thu, Jun 04, 2020 at 10:35:12AM -0400, Jim Quinlan wrote:
> On Thu, Jun 4, 2020 at 9:53 AM Nicolas Saenz Julienne
> <nsaenzjulienne@suse.de> wrote:
> > On Wed, 2020-06-03 at 15:20 -0400, Jim Quinlan wrote:

...

> > > +     phys = virt_to_phys(ret);
> > > +     pfn =  phys >> PAGE_SHIFT;
> >
> > nit: not sure it really pays off to have a pfn variable here.
> Did it for readability; the compiler's optimization should take care
> of any extra variables.  But I can switch if you insist.

One side note: please, try to get familiar with existing helpers in the kernel.
For example, above line is like

	pfn = PFN_DOWN(phys);

...

> > > +     if (!WARN_ON(!dev) && dev->dma_pfn_offset_map)

> > > +             *dma_handle -= PFN_PHYS(
> > > +                     dma_pfn_offset_from_phys_addr(dev, phys));

Don't do such indentation, esp. we have now 100! :-)

-- 
With Best Regards,
Andy Shevchenko


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Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

[Jim Quinlan via iommu]

Hi Andy,

On Thu, Jun 4, 2020 at 11:05 AM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Thu, Jun 04, 2020 at 10:35:12AM -0400, Jim Quinlan wrote:
> > On Thu, Jun 4, 2020 at 9:53 AM Nicolas Saenz Julienne
> > <nsaenzjulienne@suse.de> wrote:
> > > On Wed, 2020-06-03 at 15:20 -0400, Jim Quinlan wrote:
>
> ...
>
> > > > +     phys = virt_to_phys(ret);
> > > > +     pfn =  phys >> PAGE_SHIFT;
> > >
> > > nit: not sure it really pays off to have a pfn variable here.
> > Did it for readability; the compiler's optimization should take care
> > of any extra variables.  But I can switch if you insist.
>
> One side note: please, try to get familiar with existing helpers in the kernel.
> For example, above line is like
>
>         pfn = PFN_DOWN(phys);
I just used the term in the original code; will change to PFN_DOWN().

>
> ...
>
> > > > +     if (!WARN_ON(!dev) && dev->dma_pfn_offset_map)
>
> > > > +             *dma_handle -= PFN_PHYS(
> > > > +                     dma_pfn_offset_from_phys_addr(dev, phys));
>
> Don't do such indentation, esp. we have now 100! :-)

Got it.  Thanks,
Jim Quinlan
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
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Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

[Nicolas Saenz Julienne]

[-- Attachment #1.1: Type: text/plain, Size: 9715 bytes --]

Hi Jim,

On Thu, 2020-06-04 at 10:35 -0400, Jim Quinlan wrote:

[...]

> > > --- a/arch/sh/kernel/dma-coherent.c
> > > +++ b/arch/sh/kernel/dma-coherent.c
> > > @@ -14,6 +14,8 @@ void *arch_dma_alloc(struct device *dev, size_t size,
> > > dma_addr_t *dma_handle,
> > >  {
> > >       void *ret, *ret_nocache;
> > >       int order = get_order(size);
> > > +     unsigned long pfn;
> > > +     phys_addr_t phys;
> > > 
> > >       gfp |= __GFP_ZERO;
> > > 
> > > @@ -34,11 +36,14 @@ void *arch_dma_alloc(struct device *dev, size_t size,
> > > dma_addr_t *dma_handle,
> > >               return NULL;
> > >       }
> > > 
> > > -     split_page(pfn_to_page(virt_to_phys(ret) >> PAGE_SHIFT), order);
> > > +     phys = virt_to_phys(ret);
> > > +     pfn =  phys >> PAGE_SHIFT;
> > 
> > nit: not sure it really pays off to have a pfn variable here.
> Did it for readability; the compiler's optimization should take care
> of any extra variables.  But I can switch if you insist.

No need.

[...]

> > > diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > > b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > > index 055eb0b8e396..2d66d415b6c3 100644
> > > --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > > +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > > @@ -898,7 +898,10 @@ static int sun6i_csi_probe(struct platform_device
> > > *pdev)
> > > 
> > >       sdev->dev = &pdev->dev;
> > >       /* The DMA bus has the memory mapped at 0 */
> > > -     sdev->dev->dma_pfn_offset = PHYS_OFFSET >> PAGE_SHIFT;
> > > +     ret = attach_uniform_dma_pfn_offset(sdev->dev,
> > > +                                         PHYS_OFFSET >> PAGE_SHIFT);
> > > +     if (ret)
> > > +             return ret;
> > > 
> > >       ret = sun6i_csi_resource_request(sdev, pdev);
> > >       if (ret)
> > > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > > index 96d8cfb14a60..c89333b0a5fb 100644
> > > --- a/drivers/of/address.c
> > > +++ b/drivers/of/address.c
> > > @@ -918,6 +918,70 @@ void __iomem *of_io_request_and_map(struct
> > > device_node
> > > *np, int index,
> > >  }
> > >  EXPORT_SYMBOL(of_io_request_and_map);
> > > 
> > > +static int attach_dma_pfn_offset_map(struct device *dev,
> > > +                                  struct device_node *node, int
> > > num_ranges)
> > 
> > As with the previous review, please take this comment with a grain of salt.
> > 
> > I think there should be a clear split between what belongs to OF and what
> > belongs to the core device infrastructure.
> > 
> > OF's job should be to parse DT and provide a list/array of ranges, whereas
> > the
> > core device infrastructure should provide an API to assign a list of
> > ranges/offset to a device.
> > 
> > As a concrete example, you're forcing devices like the sta2x11 to build with
> > OF
> > support, which, being an Intel device, it's pretty odd. But I'm also
> > thinking
> > of how will all this fit once an ACPI device wants to use it.
> To fix this I only have to move attach_uniform_dma_pfn_offset() from
> of/address.c to say include/linux/dma-mapping.h.  It has no
> dependencies on OF.  Do you agree?

Yes that seems nicer. In case you didn't had it in mind already, I'd change the
function name to match the naming scheme they use there.

On the other hand, I'd also move the non OF parts of the non unifom dma_offset
version of the function there.

> > Expanding on this idea, once you have a split between the OF's and device
> > core
> > roles, it transpires that of_dma_get_range()'s job should only be to provide
> > the ranges in a device understandable structure and of_dma_configre()'s to
> > actually assign the device's parameters. This would obsolete patch #7.
> 
> I think you mean patch #8.

Yes, my bad.

> I agree with you.  The reason I needed a "struct device *"  in the call is
> because I wanted to make sure the memory that is alloc'd belongs to the
> device that needs it.  If I do a regular kzalloc(), this memory  will become
> a leak once someone starts unbinding/binding their device.  Also, in  all
> uses of of_dma_rtange() -- there is only one --  a dev is required as one
> can't attach an offset map to NULL.
> 
> I do see that there are a number of functions in drivers/of/*.c that
> take 'struct device *dev' as an argument so there is precedent for
> something like this.  Regardless, I need an owner to the memory I
> alloc().

I understand the need for dev to be around, devm_*() is key. But also it's
important to keep the functions on purpose. And if of_dma_get_range() starts
setting ranges it calls, for the very least, for a function rename. Although
I'd rather split the parsing and setting of ranges as mentioned earlier. That
said, I get that's a more drastic move.

Talking about drastic moves. How about getting rid of the concept of
dma_pfn_offset for drivers altogether. Let them provide dma_pfn_offset_regions
(even when there is only one). I feel it's conceptually nicer, as you'd be
dealing only in one currency, so to speak, and you'd centralize the bus DMA
ranges setter function which is always easier to maintain.

I'd go as far as not creating a special case for uniform offsets. Let just set
cpu_end and dma_end to -1 so we always get a match. It's slightly more compute
heavy, but I don't think it's worth the optimization.

Just my two cents :)

> > > +{
> > > +     struct of_range_parser parser;
> > > +     struct of_range range;
> > > +     struct dma_pfn_offset_region *r;
> > > +
> > > +     r = devm_kcalloc(dev, num_ranges + 1,
> > > +                      sizeof(struct dma_pfn_offset_region), GFP_KERNEL);
> > > +     if (!r)
> > > +             return -ENOMEM;
> > > +     dev->dma_pfn_offset_map = r;
> > > +     of_dma_range_parser_init(&parser, node);
> > > +
> > > +     /*
> > > +      * Record all info for DMA ranges array.  We could
> > > +      * just use the of_range struct, but if we did that it
> > > +      * would require more calculations for phys_to_dma and
> > > +      * dma_to_phys conversions.
> > > +      */
> > > +     for_each_of_range(&parser, &range) {
> > > +             r->cpu_start = range.cpu_addr;
> > > +             r->cpu_end = r->cpu_start + range.size - 1;
> > > +             r->dma_start = range.bus_addr;
> > > +             r->dma_end = r->dma_start + range.size - 1;
> > > +             r->pfn_offset = PFN_DOWN(range.cpu_addr)
> > > +                     - PFN_DOWN(range.bus_addr);
> > > +             r++;
> > > +     }
> > > +     return 0;
> > > +}
> > > +
> > > +
> > > +
> > > +/**
> > > + * attach_dma_pfn_offset - Assign scalar offset for all addresses.
> > > + * @dev:     device pointer; only needed for a corner case.
> > 
> > That's a huge corner :P
> Good point; I'm not really sure what percent of Linux configurations
> require a dma_pfn_offset.  I'll drop the "corner".
> 
> > > + * @dma_pfn_offset:  offset to apply when converting from phys addr
> > > + *                   to dma addr and vice versa.
> > > + *
> > > + * It returns -ENOMEM if out of memory, otherwise 0.
> > > + */
> > > +int attach_uniform_dma_pfn_offset(struct device *dev, unsigned long
> > > pfn_offset)
> > 
> > As I say above, does this really belong to of/address.c?
> No it does not.  Will fix.
> 
> > > +{
> > > +     struct dma_pfn_offset_region *r;
> > > +
> > > +     if (!dev)
> > > +             return -ENODEV;
> > > +
> > > +     if (!pfn_offset)
> > > +             return 0;
> > > +
> > > +     r = devm_kcalloc(dev, 1, sizeof(struct dma_pfn_offset_region),
> > > +                      GFP_KERNEL);
> > > +     if (!r)
> > > +             return -ENOMEM;
> > 
> > I think you're missing this:
> > 
> >         dev->dma_pfn_offset_map = r;
> > 
> That's a showstopper!  DanC also pointed it out but I still didn't see
> it.  Thanks!
> 
> > > +
> > > +     r->uniform_offset = true;
> > > +     r->pfn_offset = pfn_offset;
> > > +
> > > +     return 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(attach_uniform_dma_pfn_offset);
> > > +
> > >  /**
> > >   * of_dma_get_range - Get DMA range info
> > >   * @dev:     device pointer; only needed for a corner case.
> > > @@ -933,7 +997,7 @@ EXPORT_SYMBOL(of_io_request_and_map);
> > >   *   CPU addr (phys_addr_t)  : pna cells
> > >   *   size                    : nsize cells
> > >   *
> > > - * It returns -ENODEV if "dma-ranges" property was not found
> > > + * It returns -ENODEV if !dev or "dma-ranges" property was not found
> > >   * for this device in DT.
> > >   */
> > >  int of_dma_get_range(struct device *dev, struct device_node *np, u64
> > > *dma_addr,
> > > @@ -946,7 +1010,13 @@ int of_dma_get_range(struct device *dev, struct
> > > device_node *np, u64 *dma_addr,
> > >       bool found_dma_ranges = false;
> > >       struct of_range_parser parser;
> > >       struct of_range range;
> > > +     phys_addr_t cpu_start = ~(phys_addr_t)0;
> > >       u64 dma_start = U64_MAX, dma_end = 0, dma_offset = 0;
> > > +     bool dma_multi_pfn_offset = false;
> > > +     int num_ranges = 0;
> > > +
> > > +     if (!dev)
> > > +             return -ENODEV;
> > 
> > Shouldn't this be part of patch #7?
> Do you mean #8?  Do you mean the test for !dev?   It is not required
> for #8 so I thought I'd keep these two changes separate.  I could
> squash them.

#8, of course.

It's more of a subjective matter, but to me it fits better #8's description and
keeps this one more focused. That said, it's just a comment, do as you please.

Regads,
Nicolas


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Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

[Jim Quinlan via iommu]

Hi Nicolas,

On Thu, Jun 4, 2020 at 12:52 PM Nicolas Saenz Julienne
<nsaenzjulienne@suse.de> wrote:
>
> Hi Jim,
>
> On Thu, 2020-06-04 at 10:35 -0400, Jim Quinlan wrote:
>
> [...]
>
> > > > --- a/arch/sh/kernel/dma-coherent.c
> > > > +++ b/arch/sh/kernel/dma-coherent.c
> > > > @@ -14,6 +14,8 @@ void *arch_dma_alloc(struct device *dev, size_t size,
> > > > dma_addr_t *dma_handle,
> > > >  {
> > > >       void *ret, *ret_nocache;
> > > >       int order = get_order(size);
> > > > +     unsigned long pfn;
> > > > +     phys_addr_t phys;
> > > >
> > > >       gfp |= __GFP_ZERO;
> > > >
> > > > @@ -34,11 +36,14 @@ void *arch_dma_alloc(struct device *dev, size_t size,
> > > > dma_addr_t *dma_handle,
> > > >               return NULL;
> > > >       }
> > > >
> > > > -     split_page(pfn_to_page(virt_to_phys(ret) >> PAGE_SHIFT), order);
> > > > +     phys = virt_to_phys(ret);
> > > > +     pfn =  phys >> PAGE_SHIFT;
> > >
> > > nit: not sure it really pays off to have a pfn variable here.
> > Did it for readability; the compiler's optimization should take care
> > of any extra variables.  But I can switch if you insist.
>
> No need.
>
> [...]
>
> > > > diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > > > b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > > > index 055eb0b8e396..2d66d415b6c3 100644
> > > > --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > > > +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> > > > @@ -898,7 +898,10 @@ static int sun6i_csi_probe(struct platform_device
> > > > *pdev)
> > > >
> > > >       sdev->dev = &pdev->dev;
> > > >       /* The DMA bus has the memory mapped at 0 */
> > > > -     sdev->dev->dma_pfn_offset = PHYS_OFFSET >> PAGE_SHIFT;
> > > > +     ret = attach_uniform_dma_pfn_offset(sdev->dev,
> > > > +                                         PHYS_OFFSET >> PAGE_SHIFT);
> > > > +     if (ret)
> > > > +             return ret;
> > > >
> > > >       ret = sun6i_csi_resource_request(sdev, pdev);
> > > >       if (ret)
> > > > diff --git a/drivers/of/address.c b/drivers/of/address.c
> > > > index 96d8cfb14a60..c89333b0a5fb 100644
> > > > --- a/drivers/of/address.c
> > > > +++ b/drivers/of/address.c
> > > > @@ -918,6 +918,70 @@ void __iomem *of_io_request_and_map(struct
> > > > device_node
> > > > *np, int index,
> > > >  }
> > > >  EXPORT_SYMBOL(of_io_request_and_map);
> > > >
> > > > +static int attach_dma_pfn_offset_map(struct device *dev,
> > > > +                                  struct device_node *node, int
> > > > num_ranges)
> > >
> > > As with the previous review, please take this comment with a grain of salt.
> > >
> > > I think there should be a clear split between what belongs to OF and what
> > > belongs to the core device infrastructure.
> > >
> > > OF's job should be to parse DT and provide a list/array of ranges, whereas
> > > the
> > > core device infrastructure should provide an API to assign a list of
> > > ranges/offset to a device.
> > >
> > > As a concrete example, you're forcing devices like the sta2x11 to build with
> > > OF
> > > support, which, being an Intel device, it's pretty odd. But I'm also
> > > thinking
> > > of how will all this fit once an ACPI device wants to use it.
> > To fix this I only have to move attach_uniform_dma_pfn_offset() from
> > of/address.c to say include/linux/dma-mapping.h.  It has no
> > dependencies on OF.  Do you agree?
>
> Yes that seems nicer. In case you didn't had it in mind already, I'd change the
> function name to match the naming scheme they use there.
>
> On the other hand, I'd also move the non OF parts of the non unifom dma_offset
> version of the function there.
>
> > > Expanding on this idea, once you have a split between the OF's and device
> > > core
> > > roles, it transpires that of_dma_get_range()'s job should only be to provide
> > > the ranges in a device understandable structure and of_dma_configre()'s to
> > > actually assign the device's parameters. This would obsolete patch #7.
> >
> > I think you mean patch #8.
>
> Yes, my bad.
>
> > I agree with you.  The reason I needed a "struct device *"  in the call is
> > because I wanted to make sure the memory that is alloc'd belongs to the
> > device that needs it.  If I do a regular kzalloc(), this memory  will become
> > a leak once someone starts unbinding/binding their device.  Also, in  all
> > uses of of_dma_rtange() -- there is only one --  a dev is required as one
> > can't attach an offset map to NULL.
> >
> > I do see that there are a number of functions in drivers/of/*.c that
> > take 'struct device *dev' as an argument so there is precedent for
> > something like this.  Regardless, I need an owner to the memory I
> > alloc().
>
> I understand the need for dev to be around, devm_*() is key. But also it's
> important to keep the functions on purpose. And if of_dma_get_range() starts
> setting ranges it calls, for the very least, for a function rename. Although
> I'd rather split the parsing and setting of ranges as mentioned earlier. That
> said, I get that's a more drastic move.

I agree with you.  I could do this from device.c:

        of_dma_get_num_ranges(..., &num_ranges); /* new function */
        r = devm_kcalloc(dev, num_ranges + 1, sizeof(*r), GFP_KERNEL);
        of_dma_get_range(np, &dma_addr, &paddr, &size, r, num_ranges);

The problem here is that there could be four ranges, all with
offset=0.  My current code would optimize this case out but the above
would have us holding useless memory and looping through the four
ranges on every dma <=> phys conversion only to add 0.

>
> Talking about drastic moves. How about getting rid of the concept of
> dma_pfn_offset for drivers altogether. Let them provide dma_pfn_offset_regions
> (even when there is only one). I feel it's conceptually nicer, as you'd be
> dealing only in one currency, so to speak, and you'd centralize the bus DMA
> ranges setter function which is always easier to maintain.
Do you agree that we have to somehow hang this info on the struct
device structure?  Because in the dma2phys() and phys2dma() all you
have is the dev parameter.  I don't see how this  can be done w/o
involving dev.
>
> I'd go as far as not creating a special case for uniform offsets. Let just set
> cpu_end and dma_end to -1 so we always get a match. It's slightly more compute
> heavy, but I don't think it's worth the optimization.
Well, there are two subcases here.  One where we do know the bounds
and one where we do not.  I suppose for the latter I could have the
drivers calling it with begin=0 and end=~(dma_addr_t)0.  Let me give
this some thought...

>
> Just my two cents :)

Worth much more than $0.02 IMO :-)

BTW, I tried putting the "if (dev->dma_pfn_offset_map)" clause inside
the inline functions but the problem is that it slows the fastpath;
consider the following code from dma-direct.h

        if (dev->dma_pfn_offset_map) {
                unsigned long dma_pfn_offset =
dma_pfn_offset_from_phys_addr(dev, paddr);

                dev_addr -= ((dma_addr_t)dma_pfn_offset << PAGE_SHIFT);
        }
        return dev_addr;

becomes

        unsigned long dma_pfn_offset  =
dma_pfn_offset_from_phys_addr(dev, paddr);

        dev_addr -= ((dma_addr_t)dma_pfn_offset << PAGE_SHIFT);
        return dev_addr;

So those configurations that  have no dma_pfn_offsets are doing an
unnecessary shift and add.

Thanks much,
Jim Quinlan

>
> > > > +{
> > > > +     struct of_range_parser parser;
> > > > +     struct of_range range;
> > > > +     struct dma_pfn_offset_region *r;
> > > > +
> > > > +     r = devm_kcalloc(dev, num_ranges + 1,
> > > > +                      sizeof(struct dma_pfn_offset_region), GFP_KERNEL);
> > > > +     if (!r)
> > > > +             return -ENOMEM;
> > > > +     dev->dma_pfn_offset_map = r;
> > > > +     of_dma_range_parser_init(&parser, node);
> > > > +
> > > > +     /*
> > > > +      * Record all info for DMA ranges array.  We could
> > > > +      * just use the of_range struct, but if we did that it
> > > > +      * would require more calculations for phys_to_dma and
> > > > +      * dma_to_phys conversions.
> > > > +      */
> > > > +     for_each_of_range(&parser, &range) {
> > > > +             r->cpu_start = range.cpu_addr;
> > > > +             r->cpu_end = r->cpu_start + range.size - 1;
> > > > +             r->dma_start = range.bus_addr;
> > > > +             r->dma_end = r->dma_start + range.size - 1;
> > > > +             r->pfn_offset = PFN_DOWN(range.cpu_addr)
> > > > +                     - PFN_DOWN(range.bus_addr);
> > > > +             r++;
> > > > +     }
> > > > +     return 0;
> > > > +}
> > > > +
> > > > +
> > > > +
> > > > +/**
> > > > + * attach_dma_pfn_offset - Assign scalar offset for all addresses.
> > > > + * @dev:     device pointer; only needed for a corner case.
> > >
> > > That's a huge corner :P
> > Good point; I'm not really sure what percent of Linux configurations
> > require a dma_pfn_offset.  I'll drop the "corner".
> >
> > > > + * @dma_pfn_offset:  offset to apply when converting from phys addr
> > > > + *                   to dma addr and vice versa.
> > > > + *
> > > > + * It returns -ENOMEM if out of memory, otherwise 0.
> > > > + */
> > > > +int attach_uniform_dma_pfn_offset(struct device *dev, unsigned long
> > > > pfn_offset)
> > >
> > > As I say above, does this really belong to of/address.c?
> > No it does not.  Will fix.
> >
> > > > +{
> > > > +     struct dma_pfn_offset_region *r;
> > > > +
> > > > +     if (!dev)
> > > > +             return -ENODEV;
> > > > +
> > > > +     if (!pfn_offset)
> > > > +             return 0;
> > > > +
> > > > +     r = devm_kcalloc(dev, 1, sizeof(struct dma_pfn_offset_region),
> > > > +                      GFP_KERNEL);
> > > > +     if (!r)
> > > > +             return -ENOMEM;
> > >
> > > I think you're missing this:
> > >
> > >         dev->dma_pfn_offset_map = r;
> > >
> > That's a showstopper!  DanC also pointed it out but I still didn't see
> > it.  Thanks!
> >
> > > > +
> > > > +     r->uniform_offset = true;
> > > > +     r->pfn_offset = pfn_offset;
> > > > +
> > > > +     return 0;
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(attach_uniform_dma_pfn_offset);
> > > > +
> > > >  /**
> > > >   * of_dma_get_range - Get DMA range info
> > > >   * @dev:     device pointer; only needed for a corner case.
> > > > @@ -933,7 +997,7 @@ EXPORT_SYMBOL(of_io_request_and_map);
> > > >   *   CPU addr (phys_addr_t)  : pna cells
> > > >   *   size                    : nsize cells
> > > >   *
> > > > - * It returns -ENODEV if "dma-ranges" property was not found
> > > > + * It returns -ENODEV if !dev or "dma-ranges" property was not found
> > > >   * for this device in DT.
> > > >   */
> > > >  int of_dma_get_range(struct device *dev, struct device_node *np, u64
> > > > *dma_addr,
> > > > @@ -946,7 +1010,13 @@ int of_dma_get_range(struct device *dev, struct
> > > > device_node *np, u64 *dma_addr,
> > > >       bool found_dma_ranges = false;
> > > >       struct of_range_parser parser;
> > > >       struct of_range range;
> > > > +     phys_addr_t cpu_start = ~(phys_addr_t)0;
> > > >       u64 dma_start = U64_MAX, dma_end = 0, dma_offset = 0;
> > > > +     bool dma_multi_pfn_offset = false;
> > > > +     int num_ranges = 0;
> > > > +
> > > > +     if (!dev)
> > > > +             return -ENODEV;
> > >
> > > Shouldn't this be part of patch #7?
> > Do you mean #8?  Do you mean the test for !dev?   It is not required
> > for #8 so I thought I'd keep these two changes separate.  I could
> > squash them.
>
> #8, of course.
>
> It's more of a subjective matter, but to me it fits better #8's description and
> keeps this one more focused. That said, it's just a comment, do as you please.
>
> Regads,
> Nicolas
>
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Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

[Nicolas Saenz Julienne]

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Hi Christoph,
a question arouse, is there a real value to dealing with PFNs (as opposed to
real addresses) in the core DMA code/structures? I see that in some cases it
eases interacting with mm, but the overwhelming usage of say,
dev->dma_pfn_offset, involves shifting it.

Hi Jim,
On Thu, 2020-06-04 at 14:01 -0400, Jim Quinlan wrote:
> Hi Nicolas,

[...]

> > I understand the need for dev to be around, devm_*() is key. But also it's
> > important to keep the functions on purpose. And if of_dma_get_range() starts
> > setting ranges it calls, for the very least, for a function rename. Although
> > I'd rather split the parsing and setting of ranges as mentioned earlier.
> > That
> > said, I get that's a more drastic move.
> 
> I agree with you.  I could do this from device.c:
> 
>         of_dma_get_num_ranges(..., &num_ranges); /* new function */
>         r = devm_kcalloc(dev, num_ranges + 1, sizeof(*r), GFP_KERNEL);
>         of_dma_get_range(np, &dma_addr, &paddr, &size, r, num_ranges);
> 
> The problem here is that there could be four ranges, all with
> offset=0.  My current code would optimize this case out but the above
> would have us holding useless memory and looping through the four
> ranges on every dma <=> phys conversion only to add 0.

Point taken. Ultimately it's setting the device's dma ranges in
of_dma_get_range() that was really bothering me, so if we have to pass the
device pointer for allocations, be it.

> > Talking about drastic moves. How about getting rid of the concept of
> > dma_pfn_offset for drivers altogether. Let them provide
> > dma_pfn_offset_regions
> > (even when there is only one). I feel it's conceptually nicer, as you'd be
> > dealing only in one currency, so to speak, and you'd centralize the bus DMA
> > ranges setter function which is always easier to maintain.
> Do you agree that we have to somehow hang this info on the struct
> device structure?  Because in the dma2phys() and phys2dma() all you
> have is the dev parameter.  I don't see how this  can be done w/o
> involving dev.

Sorry I didn't make myself clear here. What bothers me is having two functions
setting the same device parameter trough different means, I'd be happy to get
rid of attach_uniform_dma_pfn_offset(), and always use the same function to set
a device's bus dma regions. Something the likes of this comes to mind:

dma_attach_pfn_offset_region(struct device *dev, struct dma_pfn_offset_regions *r)

We could maybe use some helper macros for the linear case. But that's the gist
of it.

Also, it goes hand in hand with the comment below. Why having a special case
for non sparse DMA offsets in struct dma_pfn_offset_regions? The way I see it,
in this case, code simplicity is more interesting than a small optimization.

> > I'd go as far as not creating a special case for uniform offsets. Let just
> > set
> > cpu_end and dma_end to -1 so we always get a match. It's slightly more
> > compute
> > heavy, but I don't think it's worth the optimization.
> Well, there are two subcases here.  One where we do know the bounds
> and one where we do not.  I suppose for the latter I could have the
> drivers calling it with begin=0 and end=~(dma_addr_t)0.  Let me give
> this some thought...
> 
> > Just my two cents :)
> 
> Worth much more than $0.02 IMO :-)

BTW, would you consider renaming the DMA offset struct to something simpler
like, struct bus_dma_region? It complements 'dev->bus_dma_limit' better IMO.

> BTW, I tried putting the "if (dev->dma_pfn_offset_map)" clause inside
> the inline functions but the problem is that it slows the fastpath;
> consider the following code from dma-direct.h
> 
>         if (dev->dma_pfn_offset_map) {
>                 unsigned long dma_pfn_offset =
dma_pfn_offset_from_phys_addr(dev, paddr);
> 
>                 dev_addr -= ((dma_addr_t)dma_pfn_offset << PAGE_SHIFT);
>         }
>         return dev_addr;
> 
> becomes
> 
>         unsigned long dma_pfn_offset = dma_pfn_offset_from_phys_addr(dev,
paddr);
> 
>         dev_addr -= ((dma_addr_t)dma_pfn_offset << PAGE_SHIFT);
>         return dev_addr;
> 
> So those configurations that  have no dma_pfn_offsets are doing an
> unnecessary shift and add.

Fair enough. Still not a huge difference, but I see the value being the most
common case.

Regards,
Nicolas


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Re: [PATCH v3 09/13] device core: Introduce multiple dma pfn offsets

[Jim Quinlan via iommu]

On Fri, Jun 5, 2020 at 1:27 PM Nicolas Saenz Julienne
<nsaenzjulienne@suse.de> wrote:
>
> Hi Christoph,
> a question arouse, is there a real value to dealing with PFNs (as opposed to
> real addresses) in the core DMA code/structures? I see that in some cases it
> eases interacting with mm, but the overwhelming usage of say,
> dev->dma_pfn_offset, involves shifting it.
>
> Hi Jim,
> On Thu, 2020-06-04 at 14:01 -0400, Jim Quinlan wrote:
> > Hi Nicolas,
>
> [...]
>
> > > I understand the need for dev to be around, devm_*() is key. But also it's
> > > important to keep the functions on purpose. And if of_dma_get_range() starts
> > > setting ranges it calls, for the very least, for a function rename. Although
> > > I'd rather split the parsing and setting of ranges as mentioned earlier.
> > > That
> > > said, I get that's a more drastic move.
> >
> > I agree with you.  I could do this from device.c:
> >
> >         of_dma_get_num_ranges(..., &num_ranges); /* new function */
> >         r = devm_kcalloc(dev, num_ranges + 1, sizeof(*r), GFP_KERNEL);
> >         of_dma_get_range(np, &dma_addr, &paddr, &size, r, num_ranges);
> >
> > The problem here is that there could be four ranges, all with
> > offset=0.  My current code would optimize this case out but the above
> > would have us holding useless memory and looping through the four
> > ranges on every dma <=> phys conversion only to add 0.
>
> Point taken. Ultimately it's setting the device's dma ranges in
> of_dma_get_range() that was really bothering me, so if we have to pass the
> device pointer for allocations, be it.
>
> > > Talking about drastic moves. How about getting rid of the concept of
> > > dma_pfn_offset for drivers altogether. Let them provide
> > > dma_pfn_offset_regions
> > > (even when there is only one). I feel it's conceptually nicer, as you'd be
> > > dealing only in one currency, so to speak, and you'd centralize the bus DMA
> > > ranges setter function which is always easier to maintain.
> > Do you agree that we have to somehow hang this info on the struct
> > device structure?  Because in the dma2phys() and phys2dma() all you
> > have is the dev parameter.  I don't see how this  can be done w/o
> > involving dev.
>
> Sorry I didn't make myself clear here. What bothers me is having two functions
> setting the same device parameter trough different means, I'd be happy to get
> rid of attach_uniform_dma_pfn_offset(), and always use the same function to set
> a device's bus dma regions. Something the likes of this comes to mind:
>
> dma_attach_pfn_offset_region(struct device *dev, struct dma_pfn_offset_regions *r)
>
> We could maybe use some helper macros for the linear case. But that's the gist
> of it.
>
> Also, it goes hand in hand with the comment below. Why having a special case
> for non sparse DMA offsets in struct dma_pfn_offset_regions? The way I see it,
> in this case, code simplicity is more interesting than a small optimization.
I've removed the special case and also need for 'dev' in
of_dma_get_range().  v4 is comming...
>
> > > I'd go as far as not creating a special case for uniform offsets. Let just
> > > set
> > > cpu_end and dma_end to -1 so we always get a match. It's slightly more
> > > compute
> > > heavy, but I don't think it's worth the optimization.
> > Well, there are two subcases here.  One where we do know the bounds
> > and one where we do not.  I suppose for the latter I could have the
> > drivers calling it with begin=0 and end=~(dma_addr_t)0.  Let me give
> > this some thought...
> >
> > > Just my two cents :)
> >
> > Worth much more than $0.02 IMO :-)
>
> BTW, would you consider renaming the DMA offset struct to something simpler
> like, struct bus_dma_region? It complements 'dev->bus_dma_limit' better IMO.
Will do

Thanks,
Jim
>
> > BTW, I tried putting the "if (dev->dma_pfn_offset_map)" clause inside
> > the inline functions but the problem is that it slows the fastpath;
> > consider the following code from dma-direct.h
> >
> >         if (dev->dma_pfn_offset_map) {
> >                 unsigned long dma_pfn_offset =
> dma_pfn_offset_from_phys_addr(dev, paddr);
> >
> >                 dev_addr -= ((dma_addr_t)dma_pfn_offset << PAGE_SHIFT);
> >         }
> >         return dev_addr;
> >
> > becomes
> >
> >         unsigned long dma_pfn_offset = dma_pfn_offset_from_phys_addr(dev,
> paddr);
> >
> >         dev_addr -= ((dma_addr_t)dma_pfn_offset << PAGE_SHIFT);
> >         return dev_addr;
> >
> > So those configurations that  have no dma_pfn_offsets are doing an
> > unnecessary shift and add.
>
> Fair enough. Still not a huge difference, but I see the value being the most
> common case.
>
> Regards,
> Nicolas
>
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