Messages in this thread Patch in this message | | | Date | Wed, 11 May 2011 12:06:55 +0200 | From | Erik Slagter <> | Subject | [PATCH 001/001]: USB: cdc_acm: Fix oops when Droids MuIn LCD is connected |
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From: Erik Slagter <erik@slagter.name>
The Droids MuIn LCD operates like a serial remote terminal. Data received are displayed directly on the LCD. This patch fixes the kernel null pointer oops when it is plugged in.
Add NO_DATA_INTERFACE quirk to tell the driver that "control" and "data" interfaces are not separated for this device, which prevents dereferencing a null pointer in the device probe code.
Signed-off-by: Erik Slagter <erik@slagter.name> Signed-off-by: Maxin B. John <maxin.john@gmail.com> Tested-by: Erik Slagter <erik@slagter.name> --- This patch applies to vanilla kernel 2.6.38.2, but I am quite confident it will apply to any recent kernel. It was created by Maxin John after I located the problem, slightly modified by me and tested by me, so blame me if it breaks anything.
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index e057e53..caa2535 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -946,7 +946,7 @@ static int acm_probe(struct usb_interface *intf, u8 ac_management_function = 0; u8 call_management_function = 0; int call_interface_num = -1; - int data_interface_num; + int data_interface_num = -1; unsigned long quirks; int num_rx_buf; int i; @@ -1030,7 +1030,11 @@ next_desc: if (!union_header) { if (call_interface_num > 0) { dev_dbg(&intf->dev, "No union descriptor, using call management descriptor\n"); - data_interface = usb_ifnum_to_if(usb_dev, (data_interface_num = call_interface_num)); + /* quirks for Droids MuIn LCD */ + if (quirks & NO_DATA_INTERFACE) + data_interface = usb_ifnum_to_if(usb_dev, 0); + else + data_interface = usb_ifnum_to_if(usb_dev, (data_interface_num = call_interface_num)); control_interface = intf; } else { if (intf->cur_altsetting->desc.bNumEndpoints != 3) { @@ -1622,6 +1626,11 @@ static const struct usb_device_id acm_ids[] = { .driver_info = NOT_A_MODEM, },
+ /* Support for Droids MuIn LCD */ + { USB_DEVICE(0x04d8, 0x000b), + .driver_info = NO_DATA_INTERFACE, + }, + /* control interfaces without any protocol set */ { USB_INTERFACE_INFO(USB_CLASS_COMM, USB_CDC_SUBCLASS_ACM, USB_CDC_PROTO_NONE) }, diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h index b4ea54d..683104a 100644 --- a/drivers/usb/class/cdc-acm.h +++ b/drivers/usb/class/cdc-acm.h @@ -137,3 +137,4 @@ struct acm { #define SINGLE_RX_URB 2 #define NO_CAP_LINE 4 #define NOT_A_MODEM 8 +#define NO_DATA_INTERFACE 16
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