[PATCH v2 2/6] hid: Parse the device before adding it

From: Henrik Rydberg
Date: Sun Apr 22 2012 - 02:04:08 EST

The hid bus is populated by devices created by the usb and bluetooth
subsystems. The hid device is then broadcast to userland via uevents.
Currently, the parsing of the hid reports is done during probe of
the hid device, after the device has been broadcast. In order to
allow for the report descriptors to influence the device properties,
it is desirable to parse the device _before_ it is broadcast to

Specific in-kernel device drivers, in particular those with report
fixup routines, are not affected by this patch. Out-of-tree drivers
with fixups is a known issue still to be addressed.

Signed-off-by: Henrik Rydberg <rydberg@xxxxxxxxxxx>
drivers/hid/hid-core.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 3ed13b4..5378cf6 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -662,7 +662,7 @@ int hid_parse_report(struct hid_device *device, __u8 *start,

- if (device->driver->report_fixup)
+ if (device->driver && device->driver->report_fixup)
start = device->driver->report_fixup(device, start, &size);

device->rdesc = kmemdup(start, size, GFP_KERNEL);
@@ -2095,6 +2095,17 @@ int hid_add_device(struct hid_device *hdev)
&& (hid_ignore(hdev) || (hdev->quirks & HID_QUIRK_IGNORE)))
return -ENODEV;

+ /*
+ * Parse generically handled devices early to allow for
+ * report-defined device groups.
+ */
+ if (hid_ignore_special_drivers ||
+ !hid_match_id(hdev, hid_have_special_driver)) {
+ ret = hid_parse(hdev);
+ if (ret)
+ return ret;
+ }
/* XXX hack, any other cleaner solution after the driver core
* is converted to allow more than 20 bytes as the device name? */
dev_set_name(&hdev->dev, "%04X:%04X:%04X.%04X", hdev->bus,

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