Hi,
>
>> > pci_bus_add_devices (platform/amba)(_device_create/driver_register)
>> > | |
>> > pci_bus_add_device (device_add/driver_register)
>> > | |
>> > device_attach device_initial_probe
>> > | |
>> > __device_attach_driver __device_attach_driver
>> > |
>> > driver_probe_device
>> > |
>> > really_probe
>> > |
>> > dma_configure
>> >
>> > Similarly on the device/driver_unregister path __device_release_driver is
>> > called which inturn calls dma_deconfigure.
>> >
>> > Signed-off-by: Sricharan R <sricharan@xxxxxxxxxxxxxx>
>> > ---
>> > * Removed the dma configuration for the pci devices in case of DT
>> > from pci_dma_configure which was hanging outside separately and
>> > doing it in dma_configure function itself.
>> >
>> > drivers/base/dd.c | 9 +++++++++
>> > drivers/base/dma-mapping.c | 32 ++++++++++++++++++++++++++++++++
>> > drivers/of/platform.c | 5 +----
>> > drivers/pci/probe.c | 5 +----
>> > include/linux/dma-mapping.h | 3 +++
>> > 5 files changed, 46 insertions(+), 8 deletions(-)
>> >
>> > diff --git a/drivers/base/dd.c b/drivers/base/dd.c
>> > index a1fbf55..4882f06 100644
>> > --- a/drivers/base/dd.c
>> > +++ b/drivers/base/dd.c
>> > @@ -19,6 +19,7 @@
>> >
>> > #include <linux/device.h>
>> > #include <linux/delay.h>
>> > +#include <linux/dma-mapping.h>
>> > #include <linux/module.h>
>> > #include <linux/kthread.h>
>> > #include <linux/wait.h>
>> > @@ -356,6 +357,10 @@ 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 (driver_sysfs_add(dev)) {
>> > printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
>> > __func__, dev_name(dev));
>> > @@ -417,6 +422,8 @@ static int really_probe(struct device *dev, struct device_driver *drv)
>> > goto done;
>> >
>> > probe_failed:
>> > + dma_deconfigure(dev);
>> > +dma_failed:
>> > if (dev->bus)
>> > blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
>> > BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
>> > @@ -826,6 +833,8 @@ static void __device_release_driver(struct device *dev, struct device *parent)
>> > drv->remove(dev);
>> >
>> > device_links_driver_cleanup(dev);
>> > + dma_deconfigure(dev);
>> > +
>> > devres_release_all(dev);
>> > dev->driver = NULL;
>> > dev_set_drvdata(dev, NULL);
>> > diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
>> > index efd71cf..dfe6fd7 100644
>> > --- a/drivers/base/dma-mapping.c
>> > +++ b/drivers/base/dma-mapping.c
>> > @@ -10,6 +10,7 @@
>> > #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>
>> >
>> > @@ -341,3 +342,34 @@ 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 *_dev = dev;
>> > + int is_pci = dev_is_pci(dev);
>> > +
>> > + if (is_pci) {
>> > + _dev = pci_get_host_bridge_device(to_pci_dev(dev));
>> > + if (IS_ENABLED(CONFIG_OF) && _dev->parent &&
>> > + _dev->parent->of_node)
>> > + _dev = _dev->parent;
>> > + }
>> > +
>> > + if (_dev->of_node)
>> > + of_dma_configure(dev, _dev->of_node);
>> > +
>> > + if (is_pci)
>> > + pci_put_host_bridge_device(_dev);
>>
>> There's a fun bug here - at this point _dev is the *parent* of the
>> bridge device, so we put the refcount on the wrong device (the platform
>> device representing the host controller, rather than the PCI device
>> representing its insides), which frees the guy we're in the middle of
>> probing, and things rapidly go wrong afterwards:
>>
>> [ 1.461026] bus: 'platform': driver_probe_device: matched device
>> 40000000.pcie-controller with driver pci-host-generic
>> [ 1.471640] bus: 'platform': really_probe: probing driver
>> pci-host-generic with device 40000000.pcie-controller
>> [ 1.481678] OF: PCI: host bridge /pcie-controller@40000000 ranges:
>>
>> ...
>>
>> [ 2.158259] bus: 'pci': driver_probe_device: matched device
>> 0000:02:10.0 with driver pcieport
>> [ 2.166716] bus: 'pci': really_probe: probing driver pcieport with
>> device 0000:02:10.0
>> [ 2.174590] pci 0000:02:10.0: Driver pcieport requests probe deferral
>> [ 2.180978] pci 0000:02:10.0: Added to deferred list
>> [ 2.185915] bus: 'pci': driver_probe_device: matched device
>> 0000:02:1f.0 with driver pcieport
>> [ 2.194366] bus: 'pci': really_probe: probing driver pcieport with
>> device 0000:02:1f.0
>> [ 2.202237] pci 0000:02:1f.0: Driver pcieport requests probe deferral
>> [ 2.208625] pci 0000:02:1f.0: Added to deferred list
>> [ 2.213582] driver: 'pci-host-generic': driver_bound: bound to device
>> '���v����.pcie-controller'
>> [ 2.222293] bus: 'platform': really_probe: bound device
>> ���v����.pcie-controller to driver pci-host-generic
>> [ 2.232041] Unable to handle kernel NULL pointer dereference at
>> virtual address 00000000
>>
>> I recall debugging this same issue before, and I seem to have a local
>> version of this commit dated about 6 weeks ago where dma_configure()
>> looks like this:
>>
>> --->8---
>> int dma_configure(struct device *dev)
>> {
>> struct device *bridge = NULL, *dma_dev = dev;
>>
>> if (dev_is_pci(dev)) {
>> bridge = pci_get_host_bridge_device(to_pci_dev(dev));
>> dma_dev = bridge->parent;
>
>This would break ACPI, dma_dev would be NULL here, so from
>this standpoint (ACPI) the current patch is correct (but those [dev,_dev]
>should be renamed, they are extremely misleading so naming as
>in this hunk, which fixes DT too, is very welcome).
>
Ya, I was also thinking about the _ variable names in first place.
So i will use the names that Robin showed in his hunk and fix the
DT case that he pointed out.
Regards,
Sricharan
>On ACPI the DMA attributes are checked on the bridge's companion
>(ie its associated acpi_device).
--
To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
