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

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

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