linux-kernel - Re: [PATCH v8 21/22] PCI: add match_driver in struct pci

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Date:	Sun, 13 Jan 2013 21:01:43 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Jiang Liu <liuj97@...il.com>
Cc:	Yinghai Lu <yinghai@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Len Brown <lenb@...nel.org>,
	Taku Izumi <izumi.taku@...fujitsu.com>,
	Jiang Liu <jiang.liu@...wei.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: [PATCH v8 21/22] PCI: add match_driver in struct pci_dev

On Sunday, January 13, 2013 11:40:12 PM Jiang Liu wrote:
> On 01/13/2013 07:49 AM, Rafael J. Wysocki wrote:
> > On Friday, January 11, 2013 02:40:48 PM Yinghai Lu wrote:
> >> with that we could move out attaching driver for pci device,
> >> out of device_add for pci hot add path.
> >>
> >> pci_bus_attach_device() will attach driver to pci device.
> > 
> > Clever, but I wonder why exactly we need to do that?
> Hi Rafael,
> 	To make following sequence possible,
> 1) Create PCI device objects for hot-added PCI host bridge
> 2) Create IOMMU devices for DMAR units belong to the hot-added PCI host bridge
> 3) Bind and start all PCI devices connected to the PCI host bridge.

OK, but why exactly isn't it possible without that change?

Rafael


> >> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> >> ---
> >>  drivers/pci/bus.c        |   10 ++++++++++
> >>  drivers/pci/pci-driver.c |    6 +++++-
> >>  include/linux/pci.h      |    1 +
> >>  3 files changed, 16 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
> >> index 5f9c728..1f5916a 100644
> >> --- a/drivers/pci/bus.c
> >> +++ b/drivers/pci/bus.c
> >> @@ -160,6 +160,15 @@ pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
> >>  
> >>  void __weak pcibios_resource_survey_bus(struct pci_bus *bus) { }
> >>  
> >> +static void pci_bus_attach_device(struct pci_dev *dev)
> >> +{
> >> +	int ret;
> >> +
> >> +	dev->match_driver = true;
> >> +	ret = device_attach(&dev->dev);
> >> +	WARN_ON(ret < 0);
> >> +}
> >> +
> >>  /**
> >>   * pci_bus_add_device - add a single device
> >>   * @dev: device to add
> >> @@ -181,6 +190,7 @@ int pci_bus_add_device(struct pci_dev *dev)
> >>  	if (retval)
> >>  		return retval;
> >>  
> >> +	pci_bus_attach_device(dev);
> >>  	dev->is_added = 1;
> >>  	pci_proc_attach_device(dev);
> >>  	pci_create_sysfs_dev_files(dev);
> >> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> >> index f79cbcd..acdcc3c 100644
> >> --- a/drivers/pci/pci-driver.c
> >> +++ b/drivers/pci/pci-driver.c
> >> @@ -1186,9 +1186,13 @@ pci_dev_driver(const struct pci_dev *dev)
> >>  static int pci_bus_match(struct device *dev, struct device_driver *drv)
> >>  {
> >>  	struct pci_dev *pci_dev = to_pci_dev(dev);
> >> -	struct pci_driver *pci_drv = to_pci_driver(drv);
> >> +	struct pci_driver *pci_drv;
> >>  	const struct pci_device_id *found_id;
> >>  
> >> +	if (!pci_dev->match_driver)
> >> +		return 0;
> >> +
> >> +	pci_drv = to_pci_driver(drv);
> >>  	found_id = pci_match_device(pci_drv, pci_dev);
> >>  	if (found_id)
> >>  		return 1;
> >> diff --git a/include/linux/pci.h b/include/linux/pci.h
> >> index 907b455..d73af08 100644
> >> --- a/include/linux/pci.h
> >> +++ b/include/linux/pci.h
> >> @@ -286,6 +286,7 @@ struct pci_dev {
> >>  	unsigned int	irq;
> >>  	struct resource resource[DEVICE_COUNT_RESOURCE]; /* I/O and memory regions + expansion ROMs */
> >>  
> >> +	bool match_driver;
> >>  	/* These fields are used by common fixups */
> >>  	unsigned int	transparent:1;	/* Transparent PCI bridge */
> >>  	unsigned int	multifunction:1;/* Part of multi-function device */
> >>
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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