On Sun, 1 Apr 2012, Nikolai Kondrashov wrote:
> > I will be travelling for the whole day tomorrow, so I will look into this
> > onboard the airplane and will try to come up with a fix.
>
> Great! Thank you :)!
Please let me know whether the patch below fixes the rebinding for your
drivers that replace the report descriptor. I believe it should. Thanks in
advance for testing.
From: Jiri Kosina <jkosina@xxxxxxx>
Subject: [PATCH] HID: make hid_parse() reentrant
It is possible to rebind the drivers on HID bus manually from userspace
(through sysfs bind/unbind facility). This way, we can easily allow drivers to
claim device IDs even if this doesn't happen automatically through explicit
hid_have_special_driver[] entry.
If driver is rebound, hid_parse() sees the HID_STATE_PARSED flag set, and
doesn't proceed parsing the report descriptor again.
This might however be unwanted in cases when the newly rebound driver does
a report descriptor fixup, as it doesn't get parsed again with the replaced
values.
Instead of bailing out directly when HID_STAT_PARSED flag is set, throw
away the old report descriptor stored in hid_device->rdesc, and let the
whole rdesc parsing be restarted (with ->report_fixup callback of the newly
rebound driver being called prior to the actual parsing).
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
---
include/linux/hid.h | 12 ++++++++++--
1 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 3a95da6..f771eba 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -807,8 +807,16 @@ static inline int __must_check hid_parse(struct hid_device *hdev)
{
int ret;
- if (hdev->status & HID_STAT_PARSED)
- return 0;
+ if (hdev->status & HID_STAT_PARSED) {
+ /*
+ * We want to be re-entrant to allow for dynamic driver
+ * rebinding and still allow rdescs to be replaced and
+ * and re-parsed once the driver has been dynamically
+ * rebound
+ */
+ kfree(hdev->rdesc);
+ hdev->status &= ~HID_STAT_PARSED;
+ }
ret = hdev->ll_driver->parse(hdev);
if (!ret)
--
Jiri Kosina
SUSE Labs
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