From d86db25e53fa69e3e97f3b55dd82a70689787c5d Mon Sep 17 00:00:00 2001 From: Julius Werner Date: Tue, 4 Mar 2014 11:27:38 -0800 Subject: [PATCH] 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 Cc: stable Signed-off-by: Greg Kroah-Hartman --- 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) { -- 2.20.1