stmf0: Do not send more data than requested for GET_DESCRIPTOR

When Linux boots, it asks for only the first 8 bytes of the device
descriptor; we must limit the amount of data sent back to that amount
or USB will get wedged.

Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/src/stmf0/ao_usb_stm.c b/src/stmf0/ao_usb_stm.c
index a67fc868f63db8e5c557a33ef0fa1e1f23686e3b..63b35b249b55217074033b557d72867db422997d 100644 (file)
--- a/src/stmf0/ao_usb_stm.c
+++ b/src/stmf0/ao_usb_stm.c
@@ -683,7 +683,7 @@ ao_usb_serial_init(void)
 /* Walk through the list of descriptors and find a match
  */
 static void
-ao_usb_get_descriptor(uint16_t value)
+ao_usb_get_descriptor(uint16_t value, uint16_t length)
 {
        const uint8_t           *descriptor;
        uint8_t         type = value >> 8;
@@ -704,6 +704,8 @@ ao_usb_get_descriptor(uint16_t value)
                                len = sizeof (ao_usb_serial);
                        }
 #endif
+                       if (len > length)
+                               len = length;
                        ao_usb_ep0_in_set(descriptor, len);
                        break;
                }
@@ -748,7 +750,7 @@ ao_usb_ep0_setup(void)
                                break;
                        case AO_USB_REQ_GET_DESCRIPTOR:
                                debug ("get descriptor %d\n", ao_usb_setup.value);
-                               ao_usb_get_descriptor(ao_usb_setup.value);
+                               ao_usb_get_descriptor(ao_usb_setup.value, ao_usb_setup.length);
                                break;
                        case AO_USB_REQ_GET_CONFIGURATION:
                                debug ("get configuration %d\n", ao_usb_configuration);