@@ -84,12 +84,13 @@ static int huawei_cdc_ncm_bind(struct usbnet *usbnet_dev,
ctx = drvstate->ctx;
if (usbnet_dev->status)
- /* CDC-WMC r1.1 requires wMaxCommand to be "at least 256
- * decimal (0x100)"
+ /* The wMaxCommand buffer must be big enough to hold
+ * any message from the modem. Experience has shown
+ * that some replies are more than 256 bytes long
*/
subdriver = usb_cdc_wdm_register(ctx->control,
&usbnet_dev->status->desc,
- 256, /* wMaxCommand */
+ 1024, /* wMaxCommand */
huawei_cdc_ncm_wdm_manage_power);
if (IS_ERR(subdriver)) {
ret = PTR_ERR(subdriver);
This is a note to let you know that I have just added a patch titled net: huawei_cdc_ncm: increase command buffer size to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11.6. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 622a712fec9241edfa1a7893939ca83c76f17ad4 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B8rn=20Mork?= <bjorn@mork.no> Date: Wed, 18 Jun 2014 14:21:24 +0200 Subject: net: huawei_cdc_ncm: increase command buffer size MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Upstream commit 3acc74619b0175b7a154cf8dc54813f6faf97aa9 ] Messages from the modem exceeding 256 bytes cause communication failure. The WDM protocol is strictly "read on demand", meaning that we only poll for unread data after receiving a notification from the modem. Since we have no way to know how much data the modem has to send, we must make sure that the buffer we provide is "big enough". Message truncation does not work. Truncated messages are left unread until the modem has another message to send. Which often won't happen until the userspace application has given up waiting for the final part of the last message, and therefore sends another command. With a proper CDC WDM function there is a descriptor telling us which buffer size the modem uses. But with this vendor specific implementation there is no known way to calculate the exact "big enough" number. It is an unknown property of the modem firmware. Experience has shown that 256 is too small. The discussion of this failure ended up concluding that 512 might be too small as well. So 1024 seems like a reasonable value for now. Fixes: 41c47d8cfd68 ("net: huawei_cdc_ncm: Introduce the huawei_cdc_ncm driver") Cc: Enrico Mioso <mrkiko.rs@gmail.com> Reported-by: Dan Williams <dcbw@redhat.com> Signed-off-by: Bjørn Mork <bjorn@mork.no> Acked-By: Enrico Mioso <mrkiko.rs@gmail.com> Tested-by: Dan Williams <dcbw@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/net/usb/huawei_cdc_ncm.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) -- 1.9.1