The CDC NCM specification describes the alternate settings that a CDC
NCM interface must support. Alternate setting 0 does not allow any
network traffic but allows configuration of the interface. Alternate 1
allows network traffic but doesn't allow configuration of some of the
interface properties.
This change provides #defines for there two numbers to clarify why
usb_set_interface is being called.
Signed-off-by: Toby Gray <toby.gray@xxxxxxxxxxx>
---
drivers/net/usb/cdc_ncm.c | 11 +++++++++--
1 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 3a539a9..3df51ee 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -87,6 +87,13 @@
(sizeof(struct usb_cdc_ncm_nth16) + sizeof(struct usb_cdc_ncm_ndp16) + \
(CDC_NCM_DPT_DATAGRAMS_MAX + 1) * sizeof(struct usb_cdc_ncm_dpe16))
+/* CDC NCM ch. 5.3 describes alternate setting 0 as having no
+ * endpoints and therefore not allowing any networking traffic. */
+#define CDC_NCM_ALTSETTING_RESET 0
+/* CDC NCM ch. 5.3 describes alternate setting 1 as having the
+ * required bulk endpoints for normal operation. */
+#define CDC_NCM_ALTSETTING_DATA 1
+
struct cdc_ncm_data {
struct usb_cdc_ncm_nth16 nth16;
struct usb_cdc_ncm_ndp16 ndp16;
@@ -549,7 +556,7 @@ advance:
iface_no = ctx->data->cur_altsetting->desc.bInterfaceNumber;
/* reset data interface */
- temp = usb_set_interface(dev->udev, iface_no, 0);
+ temp = usb_set_interface(dev->udev, iface_no, CDC_NCM_ALTSETTING_RESET);
if (temp)
goto error2;
@@ -558,7 +565,7 @@ advance:
goto error2;
/* configure data interface */
- temp = usb_set_interface(dev->udev, iface_no, 1);
+ temp = usb_set_interface(dev->udev, iface_no, CDC_NCM_ALTSETTING_DATA);
if (temp)
goto error2;
--
1.7.0.4
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