This is a note to let you know that I've just added the patch titled
usb: Make DELAY_INIT quirk wait 100ms between Get Configuration
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From d86db25e53fa69e3e97f3b55dd82a70689787c5d Mon Sep 17 00:00:00 2001
From: Julius Werner <jwerner@xxxxxxxxxxxx>
Date: Tue, 4 Mar 2014 11:27:38 -0800
Subject: usb: Make DELAY_INIT quirk wait 100ms between Get Configuration
requests
The DELAY_INIT quirk only reduces the frequency of enumeration failures
with the Logitech HD Pro C920 and C930e webcams, but does not quite
eliminate them. We have found that adding a delay of 100ms between the
first and second Get Configuration request makes the device enumerate
perfectly reliable even after several weeks of extensive testing. The
reasons for that are anyone's guess, but since the DELAY_INIT quirk
already delays enumeration by a whole second, wating for another 10th of
that isn't really a big deal for the one other device that uses it, and
it will resolve the problems with these webcams.
Signed-off-by: Julius Werner <jwerner@xxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/core/config.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
index 8d72f0c65937..062967c90b2a 100644
--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -717,6 +717,10 @@ int usb_get_configuration(struct usb_device *dev)
result = -ENOMEM;
goto err;
}
+
+ if (dev->quirks & USB_QUIRK_DELAY_INIT)
+ msleep(100);
+
result = usb_get_descriptor(dev, USB_DT_CONFIG, cfgno,
bigbuffer, length);
if (result < 0) {
--
1.9.0
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