Commit:     7461b60afa62b26943e97861d87b9f9a32d7fd9c
Parent:     f238085415c56618e042252894f2fcc971add645
Author:     Russell King <[EMAIL PROTECTED]>
AuthorDate: Wed Nov 29 21:18:04 2006 +0000
Committer:  Greg Kroah-Hartman <[EMAIL PROTECTED]>
CommitDate: Wed Dec 20 10:54:41 2006 -0800

    PCI: use /sys/bus/pci/drivers/<driver>/new_id first
    Unfortunately, the .../new_id feature does not work with the 8250_pci
    The reason for this comes down to the way .../new_id is implemented.
    When PCI tries to match a driver to a device, it checks the modules
    static device ID tables _before_ checking the dynamic new_id tables.
    When a driver is capable of matching by ID, and falls back to matching
    by class (as 8250_pci does), this makes it absolutely impossible to
    specify a board by ID, and as such the correct driver_data value to
    use with it.
    Let's say you have a serial board with vendor 0x1234 and device 0x5678.
    It's class is set to PCI_CLASS_COMMUNICATION_SERIAL.
    On boot, this card is matched to the 8250_pci driver, which tries to
    probe it because it matched using the class entry.  The driver finds
    that it is unable to automatically detect the correct settings to use,
    so it returns -ENODEV.
    You know that the information the driver needs is to match this card
    using a device_data value of '7'.  So you echo 1234 5678 0 0 0 0 7
    into new_id.
    The kernel attempts to re-bind 8250_pci to this device.  However,
    because it scans the PCI driver tables, it _again_ matches the class
    entry which has the wrong device_data.  It fails.
    End of story.  You can't support the card without rebuilding the
    kernel (or writing a specific PCI probe module to support it.)
    So, can we make new_id override the driver-internal PCI ID tables?
    IOW, like this:
    From: Russell King <[EMAIL PROTECTED]>
    Signed-off-by: Greg Kroah-Hartman <[EMAIL PROTECTED]>
 drivers/pci/pci-driver.c |   10 +++-------
 1 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index e5ae3a0..de5b901 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -162,14 +162,9 @@ const struct pci_device_id *pci_match_id(const struct 
pci_device_id *ids,
 const struct pci_device_id *pci_match_device(struct pci_driver *drv,
                                             struct pci_dev *dev)
-       const struct pci_device_id *id;
        struct pci_dynid *dynid;
-       id = pci_match_id(drv->id_table, dev);
-       if (id)
-               return id;
-       /* static ids didn't match, lets look at the dynamic ones */
+       /* Look at the dynamic ids first, before the static ones */
        list_for_each_entry(dynid, &drv->dynids.list, node) {
                if (pci_match_one_device(&dynid->id, dev)) {
@@ -178,7 +173,8 @@ const struct pci_device_id *pci_match_device(struct 
pci_driver *drv,
-       return NULL;
+       return pci_match_id(drv->id_table, dev);
 static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev,
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