Messages in this thread Patch in this message | | | Subject | Re: [PATCH] dma-mapping: move dma configuration to bus infrastructure | From | Robin Murphy <> | Date | Tue, 13 Mar 2018 11:35:58 +0000 |
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On 12/03/18 15:24, Nipun Gupta wrote: > The change introduces 'dma_configure' & 'dma_deconfigure'as > bus callback functions so each bus can choose to implement > its own dma configuration function. > This eases the addition of new busses w.r.t. adding the dma > configuration functionality.
It's probably worth clarifying - either in the commit message, the kerneldoc, or both - that the bus-specific aspect is that of mapping between a given device on the bus and the relevant firmware description of its DMA configuration.
> The change also updates the PCI, Platform and ACPI bus to use > new introduced callbacks. > > Signed-off-by: Nipun Gupta <nipun.gupta@nxp.com> > --- > - This patch is based on the comments on: > https://patchwork.kernel.org/patch/10259087/ > - I have validated for PCI and platform, but not for AMBA as I > do not have infrastructure to validate it. > Can anyone please validate them on AMBA? > > drivers/amba/bus.c | 38 ++++++++++++++++++++++++----- > drivers/base/dd.c | 14 +++++++---- > drivers/base/dma-mapping.c | 41 ------------------------------- > drivers/base/platform.c | 36 ++++++++++++++++++++++----- > drivers/pci/pci-driver.c | 59 ++++++++++++++++++++++++++++++++++++--------- > include/linux/device.h | 6 +++++ > include/linux/dma-mapping.h | 12 --------- > 7 files changed, 124 insertions(+), 82 deletions(-) > > diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c > index 594c228..58241d2 100644 > --- a/drivers/amba/bus.c > +++ b/drivers/amba/bus.c > @@ -20,6 +20,8 @@ > #include <linux/sizes.h> > #include <linux/limits.h> > #include <linux/clk/clk-conf.h> > +#include <linux/acpi.h> > +#include <linux/of_device.h> > > #include <asm/irq.h> > > @@ -171,6 +173,28 @@ static int amba_pm_runtime_resume(struct device *dev) > } > #endif /* CONFIG_PM */ > > +int amba_dma_configure(struct device *dev) > +{ > + enum dev_dma_attr attr; > + int ret = 0; > + > + if (dev->of_node) { > + ret = of_dma_configure(dev, dev->of_node); > + } else if (has_acpi_companion(dev)) { > + attr = acpi_get_dma_attr(to_acpi_device_node(dev->fwnode)); > + if (attr != DEV_DMA_NOT_SUPPORTED) > + ret = acpi_dma_configure(dev, attr); > + } > + > + return ret; > +}
I would be inclined to have amba_bustype just reference platform_dma_configure() directly rather than duplicate it like this, since there's no sensible reason for them to ever differ.
> + > +void amba_dma_deconfigure(struct device *dev) > +{ > + of_dma_deconfigure(dev); > + acpi_dma_deconfigure(dev); > +} > + > static const struct dev_pm_ops amba_pm = { > .suspend = pm_generic_suspend, > .resume = pm_generic_resume, > @@ -190,12 +214,14 @@ static int amba_pm_runtime_resume(struct device *dev) > * so we call the bus "amba". > */ > struct bus_type amba_bustype = { > - .name = "amba", > - .dev_groups = amba_dev_groups, > - .match = amba_match, > - .uevent = amba_uevent, > - .pm = &amba_pm, > - .force_dma = true, > + .name = "amba", > + .dev_groups = amba_dev_groups, > + .match = amba_match, > + .uevent = amba_uevent, > + .pm = &amba_pm, > + .dma_configure = amba_dma_configure, > + .dma_deconfigure = amba_dma_deconfigure, > + .force_dma = true,
This patch should also be removing force_dma because it no longer makes sense. If DMA configuration is now done by a bus-level callback, then a bus which wants its children to get DMA configuration needs to implement that callback; there's nowhere to force a "default" global behaviour any more.
> }; > > static int __init amba_init(void) > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index de6fd09..f124f3f 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -421,9 +421,11 @@ static int really_probe(struct device *dev, struct device_driver *drv) > if (ret) > goto pinctrl_bind_failed; > > - ret = dma_configure(dev); > - if (ret) > - goto dma_failed; > + if (dev->bus->dma_configure) { > + ret = dev->bus->dma_configure(dev); > + if (ret) > + goto dma_failed; > + } > > if (driver_sysfs_add(dev)) { > printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n", > @@ -486,7 +488,8 @@ static int really_probe(struct device *dev, struct device_driver *drv) > goto done; > > probe_failed: > - dma_deconfigure(dev); > + if (dev->bus->dma_deconfigure) > + dev->bus->dma_deconfigure(dev); > dma_failed: > if (dev->bus) > blocking_notifier_call_chain(&dev->bus->p->bus_notifier, > @@ -895,7 +898,8 @@ static void __device_release_driver(struct device *dev, struct device *parent) > drv->remove(dev); > > device_links_driver_cleanup(dev); > - dma_deconfigure(dev); > + if (dev->bus->dma_deconfigure) > + dev->bus->dma_deconfigure(dev); > > devres_release_all(dev); > dev->driver = NULL; > diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c > index 3b11835..f16bd49 100644 > --- a/drivers/base/dma-mapping.c > +++ b/drivers/base/dma-mapping.c > @@ -6,11 +6,9 @@ > * Copyright (c) 2006 Tejun Heo <teheo@suse.de> > */ > > -#include <linux/acpi.h> > #include <linux/dma-mapping.h> > #include <linux/export.h> > #include <linux/gfp.h> > -#include <linux/of_device.h> > #include <linux/slab.h> > #include <linux/vmalloc.h> > > @@ -329,42 +327,3 @@ void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags) > vunmap(cpu_addr); > } > #endif > - > -/* > - * Common configuration to enable DMA API use for a device > - */ > -#include <linux/pci.h> > - > -int dma_configure(struct device *dev) > -{ > - struct device *bridge = NULL, *dma_dev = dev; > - enum dev_dma_attr attr; > - int ret = 0; > - > - if (dev_is_pci(dev)) { > - bridge = pci_get_host_bridge_device(to_pci_dev(dev)); > - dma_dev = bridge; > - if (IS_ENABLED(CONFIG_OF) && dma_dev->parent && > - dma_dev->parent->of_node) > - dma_dev = dma_dev->parent; > - } > - > - if (dma_dev->of_node) { > - ret = of_dma_configure(dev, dma_dev->of_node); > - } else if (has_acpi_companion(dma_dev)) { > - attr = acpi_get_dma_attr(to_acpi_device_node(dma_dev->fwnode)); > - if (attr != DEV_DMA_NOT_SUPPORTED) > - ret = acpi_dma_configure(dev, attr); > - } > - > - if (bridge) > - pci_put_host_bridge_device(bridge); > - > - return ret; > -} > - > -void dma_deconfigure(struct device *dev) > -{ > - of_dma_deconfigure(dev); > - acpi_dma_deconfigure(dev); > -} > diff --git a/drivers/base/platform.c b/drivers/base/platform.c > index f1bf7b3..adf94eb 100644 > --- a/drivers/base/platform.c > +++ b/drivers/base/platform.c > @@ -1130,6 +1130,28 @@ int platform_pm_restore(struct device *dev) > > #endif /* CONFIG_HIBERNATE_CALLBACKS */ > > +int platform_dma_configure(struct device *dev) > +{ > + enum dev_dma_attr attr; > + int ret = 0; > + > + if (dev->of_node) { > + ret = of_dma_configure(dev, dev->of_node); > + } else if (has_acpi_companion(dev)) { > + attr = acpi_get_dma_attr(to_acpi_device_node(dev->fwnode)); > + if (attr != DEV_DMA_NOT_SUPPORTED) > + ret = acpi_dma_configure(dev, attr); > + } > + > + return ret; > +} > + > +void platform_dma_deconfigure(struct device *dev) > +{ > + of_dma_deconfigure(dev); > + acpi_dma_deconfigure(dev); > +} > + > static const struct dev_pm_ops platform_dev_pm_ops = { > .runtime_suspend = pm_generic_runtime_suspend, > .runtime_resume = pm_generic_runtime_resume, > @@ -1137,12 +1159,14 @@ int platform_pm_restore(struct device *dev) > }; > > struct bus_type platform_bus_type = { > - .name = "platform", > - .dev_groups = platform_dev_groups, > - .match = platform_match, > - .uevent = platform_uevent, > - .pm = &platform_dev_pm_ops, > - .force_dma = true, > + .name = "platform", > + .dev_groups = platform_dev_groups, > + .match = platform_match, > + .uevent = platform_uevent, > + .pm = &platform_dev_pm_ops, > + .dma_configure = platform_dma_configure, > + .dma_deconfigure = platform_dma_deconfigure, > + .force_dma = true, > }; > EXPORT_SYMBOL_GPL(platform_bus_type); > > diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c > index 3bed6be..4a77814 100644 > --- a/drivers/pci/pci-driver.c > +++ b/drivers/pci/pci-driver.c > @@ -18,6 +18,8 @@ > #include <linux/pm_runtime.h> > #include <linux/suspend.h> > #include <linux/kexec.h> > +#include <linux/acpi.h> > +#include <linux/of_device.h> > #include "pci.h" > > struct pci_dynid { > @@ -1522,19 +1524,52 @@ static int pci_bus_num_vf(struct device *dev) > return pci_num_vf(to_pci_dev(dev)); > } > > +int pci_dma_configure(struct device *dev) > +{ > + struct device *bridge, *dma_dev;
You don't need dma_dev here; see the code removed in 09515ef5ddad for how the logic originally worked.
> + enum dev_dma_attr attr; > + int ret = 0; > + > + bridge = pci_get_host_bridge_device(to_pci_dev(dev)); > + dma_dev = bridge; > + if (IS_ENABLED(CONFIG_OF) && dma_dev->parent && > + dma_dev->parent->of_node) > + dma_dev = dma_dev->parent; > + > + if (dma_dev->of_node) { > + ret = of_dma_configure(dev, dma_dev->of_node); > + } else if (has_acpi_companion(dma_dev)) { > + attr = acpi_get_dma_attr(to_acpi_device_node(dma_dev->fwnode)); > + if (attr != DEV_DMA_NOT_SUPPORTED) > + ret = acpi_dma_configure(dev, attr); > + } > + > + pci_put_host_bridge_device(bridge); > + > + return ret; > +} > + > +void pci_dma_deconfigure(struct device *dev) > +{ > + of_dma_deconfigure(dev); > + acpi_dma_deconfigure(dev); > +} > + > struct bus_type pci_bus_type = { > - .name = "pci", > - .match = pci_bus_match, > - .uevent = pci_uevent, > - .probe = pci_device_probe, > - .remove = pci_device_remove, > - .shutdown = pci_device_shutdown, > - .dev_groups = pci_dev_groups, > - .bus_groups = pci_bus_groups, > - .drv_groups = pci_drv_groups, > - .pm = PCI_PM_OPS_PTR, > - .num_vf = pci_bus_num_vf, > - .force_dma = true, > + .name = "pci", > + .match = pci_bus_match, > + .uevent = pci_uevent, > + .probe = pci_device_probe, > + .remove = pci_device_remove, > + .shutdown = pci_device_shutdown, > + .dev_groups = pci_dev_groups, > + .bus_groups = pci_bus_groups, > + .drv_groups = pci_drv_groups, > + .pm = PCI_PM_OPS_PTR, > + .num_vf = pci_bus_num_vf, > + .dma_configure = pci_dma_configure, > + .dma_deconfigure = pci_dma_deconfigure, > + .force_dma = true, > }; > EXPORT_SYMBOL(pci_bus_type); > > diff --git a/include/linux/device.h b/include/linux/device.h > index b093405..9b2dcf6 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -88,6 +88,9 @@ extern int __must_check bus_create_file(struct bus_type *, > * @resume: Called to bring a device on this bus out of sleep mode. > * @num_vf: Called to find out how many virtual functions a device on this > * bus supports. > + * @dma_configure: Called to setup DMA configuration on a device on > + this bus. > + * @dma_deconfigure: Called to tear down the DMA configuration. > * @pm: Power management operations of this bus, callback the specific > * device driver's pm-ops. > * @iommu_ops: IOMMU specific operations for this bus, used to attach IOMMU > @@ -130,6 +133,9 @@ struct bus_type { > > int (*num_vf)(struct device *dev); > > + int (*dma_configure)(struct device *dev); > + void (*dma_deconfigure)(struct device *dev);
Seeing it laid out in the patch, I really don't think we need a deconfigure callback like this - the fact that we're just copy-pasting the existing implementation everywhere is a big hint, but more conceptually I can't see a good reason for it to ever need bus-specific behaviour in the same way that configure does.
Maybe that means we keep dma_configure() around for the sake of symmetry, but just reduce it to:
int dma_configure(struct device *dev) { if (dev->bus->dma_configure) return dev->bus->dma_configure(dev); return 0; }
Realistically though, dma_deconfigure() only exists for the sake of calling arch_teardown_dma_ops(), and that only really exists for the sake of the old ARM IOMMU code, so I'm not inclined to pretend it's anywhere near as important as the dma_configure() path in design terms.
Robin.
> + > const struct dev_pm_ops *pm; > > const struct iommu_ops *iommu_ops; > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h > index eb9eab4..039224b 100644 > --- a/include/linux/dma-mapping.h > +++ b/include/linux/dma-mapping.h > @@ -761,18 +761,6 @@ void *dma_mark_declared_memory_occupied(struct device *dev, > } > #endif /* CONFIG_HAVE_GENERIC_DMA_COHERENT */ > > -#ifdef CONFIG_HAS_DMA > -int dma_configure(struct device *dev); > -void dma_deconfigure(struct device *dev); > -#else > -static inline int dma_configure(struct device *dev) > -{ > - return 0; > -} > - > -static inline void dma_deconfigure(struct device *dev) {} > -#endif > - > /* > * Managed DMA API > */ >
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