Re: Unitech USB barcode scanner issues

On Sun, 29 Apr 2007, Bret Towe wrote:

> > There might be various reasons for this, most probably the report 
> > descriptor of the device is broken. It might then be easy to fix the 
> > report descriptor on the fly before it gets parsed, we are doing this 
> > for various broken hardware already.
> so this is a rather common issue then?

Hi Bret,

well not that common, but there are a few devices out there which have 
broken report descriptors and we are fixing them before they enter the 
parser. (some logitech keyboards, certain cymotion keyboard, etc.)

> > What product ID and vendor ID does your device have please? (you can 
> > find out from the output of lsusb command).
> Bus 005 Device 002: ID 04b4:de64 Cypress Semiconductor Corp.
> this is one of the new ones that have the broken upper case bit I'll dig 
> around see if I can find a working old one to see if its id changed 
> since old and new were both broken with hid

Please try the patch below (against 2.6.21), it could solve your problem. 
If it does, I would be interested in all other product IDs you are able to 
reproduce this bug with, so that I can prepare proper patch, handling all 
cypress hardware which is broken in the same way.

diff --git a/drivers/usb/input/hid-core.c b/drivers/usb/input/hid-core.c
index 827a75a..7cfee8d 100644
--- a/drivers/usb/input/hid-core.c
+++ b/drivers/usb/input/hid-core.c
@@ -1053,6 +1053,30 @@ static void hid_fixup_s510_descriptor(un
 	}
 }
 
+#define rdesc_swap(n1,n2) 	tmp = rdesc[n2]; \
+				rdesc[n2] = rdesc[n1]; \
+				rdesc[n1] = tmp;
+static void hid_fixup_cypress_descriptor(unsigned char *rdesc, int rsize)
+{
+	char tmp;
+
+	if (rdesc[10] == 0x29 && rdesc[12] == 0x19 &&
+	    rdesc[36] == 0x29 && rdesc[38] == 0x19 &&
+	    rdesc[59] == 0x29 && rdesc[61] == 0x19 &&
+	    rdesc[74] == 0x29 && rdesc[76] == 0x19 &&
+	    rdesc[86] == 0x29 && rdesc[88] == 0x19) {
+		info("Fixing up Cypress report descriptor\n");
+		rdesc[10] = rdesc[36] = rdesc[59] = rdesc[74] = rdesc[86] = 0x19;
+		rdesc[12] = rdesc[38] = rdesc[61] = rdesc[76] = rdesc[88] = 0x29;
+		rdesc_swap(11, 13);
+		rdesc_swap(37, 39);
+		rdesc_swap(60, 62);
+		rdesc_swap(75, 77);
+		rdesc_swap(87, 89);
+	} else
+		info("Not fixing Cypress report descriptor");
+}
+
 static struct hid_device *usb_hid_configure(struct usb_interface *intf)
 {
 	struct usb_host_interface *interface = intf->cur_altsetting;
@@ -1129,6 +1153,10 @@ static struct hid_device *usb_hid_config
 	if (quirks & HID_QUIRK_LOGITECH_S510_DESCRIPTOR)
 		hid_fixup_s510_descriptor(rdesc, rsize);
 
+	if (le16_to_cpu(dev->descriptor.idVendor) == 0x04b4 &&
+			le16_to_cpu(dev->descriptor.idProduct == 0xde64))
+			hid_fixup_cypress_descriptor(rdesc, rsize);
+
 #ifdef CONFIG_HID_DEBUG
 	printk(KERN_DEBUG __FILE__ ": report descriptor (size %u, read %d) = ", rsize, n);
 	for (n = 0; n < rsize; n++)

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