net: cdc_ncm: workaround NTB input size firmware bug (dad957d7) · Commits · 戴 / test

Some devices do not support the 8 byte variants of the NTB input size control messages despite announcing such support in their NCM or MBIM functional descriptor. According to the NCM specification, all devices must support the 4 byte variant regardless of whether or not the flag is set: If bit D5 is set in the bmNetworkCapabilities field of function’s NCM Functional Descriptor, the host may set wLength either to 4 or to 8. If wLength is 4, the function shall assume that wNtbInMaxDatagrams is to be set to zero. If wLength is 8, then the function shall use the provided value as the limit. The function shall return an error response (a STALL PID) if wLength is set to any other value. We do not set wNtbInMaxDatagrams in any case, so we can just as well unconditionally use the 4 byte variant without losing any functionality. This works around the known firmware bug, and simplifies the code considerably. Signed-off-by:

Bjørn Mork <bjorn@mork.no> Signed-off-by:

David S. Miller <davem@davemloft.net>

drivers/net/usb/cdc_ncm.c

+13 −33

Original line number	Diff line number	Diff line
		@@ -215,33 +215,14 @@ static u8 cdc_ncm_setup(struct cdc_ncm_ctx *ctx)

		/* inform device about NTB input size changes */
		if (ctx->rx_max != le32_to_cpu(ctx->ncm_parm.dwNtbInMaxSize)) {

		if (flags & USB_CDC_NCM_NCAP_NTB_INPUT_SIZE) {
		struct usb_cdc_ncm_ndp_input_size *ndp_in_sz;

		ndp_in_sz = kzalloc(sizeof(*ndp_in_sz), GFP_KERNEL);
		if (!ndp_in_sz) {
		err = -ENOMEM;
		goto size_err;
		}

		err = usb_control_msg(ctx->udev,
		usb_sndctrlpipe(ctx->udev, 0),
		USB_CDC_SET_NTB_INPUT_SIZE,
		USB_TYPE_CLASS \| USB_DIR_OUT
		\| USB_RECIP_INTERFACE,
		0, iface_no, ndp_in_sz, 8, 1000);
		kfree(ndp_in_sz);
		} else {
		__le32 *dwNtbInMaxSize;
		dwNtbInMaxSize = kzalloc(sizeof(*dwNtbInMaxSize),
		GFP_KERNEL);

		dwNtbInMaxSize = kzalloc(sizeof(*dwNtbInMaxSize), GFP_KERNEL);
		if (!dwNtbInMaxSize) {
		err = -ENOMEM;
		goto size_err;
		}
		*dwNtbInMaxSize = cpu_to_le32(ctx->rx_max);

		err = usb_control_msg(ctx->udev,
		usb_sndctrlpipe(ctx->udev, 0),
		USB_CDC_SET_NTB_INPUT_SIZE,
		@@ -249,7 +230,6 @@ static u8 cdc_ncm_setup(struct cdc_ncm_ctx *ctx)
		\| USB_RECIP_INTERFACE,
		0, iface_no, dwNtbInMaxSize, 4, 1000);
		kfree(dwNtbInMaxSize);
		}
		size_err:
		if (err < 0)
		pr_debug("Setting NTB Input Size failed\n");

Admin message