On Wed, May 25, 2016 at 3:41 PM, Bjørn Mork <bjorn@xxxxxxx> wrote: > Narasimha M <mnarasimha786@xxxxxxxxx> writes: > >> Thanks for explanation. Here data is getting corrupted before it comes >> to the usbnet itself, so after it reaches to usbnet and go through >> network stack, it is failing in tcp checksum and packet is getting >> dropped. Same driver is working with linux-3.10.20 but not working >> with linux-2.6.32.Not able to find the exact function in driver which >> sends receive packet to usbnet, not able to proceed further. Please >> suggest some pointers to proceed further. > > This is no surprise. There is no "send receive packet to usbnet". > > usbnet allocates a receive buffer and hands it to the USB host > controller. This happens in rx_submit(). Understood this. >The host controller calls the > rx_complete() callback when it gets data from the device. Here i want the help that where will be this host controller ? and how to it calls the rx_complete () callback ? Whet is the function in host controller does this. ? Ehat is the exact meaning of when device gets the data ? These things i am not able to understand. BTW iam using some 4g dongle as usb and usb driver is gobinet to support this and i am checking this on one router which has 2.6.32 kernel. I tried to use usbmon also, i got the raw data. I am trying to process it. Meanwhile i am not clear about the above explanation. Please try to explain me if you are not irritated. >This callback > will trigger further handling in the usbnet_bh() tasklet, calling > rx_process(). This again calls the minidriver specific rx_fixup() > callback if there is any, which is GobiNet's only chance of inspecting > and possibly modifying the buffer. But normally it will not touch the > buffer, since there is no fixup necessary for Gobi devices in 802.3 mode > (they transmit plain ethernet packets). rx_process() ends up calling > usbnet_skb_return() which hands the buffer over the the networking stack > using netif_rx(). > Understood > So, if we ignore the possible firmware bug workarounds in rx_fixup(), > then nothing ever touches the receive buffer in usbnet. It's just a > handle being passed around. > Understood. > Note that I don't remember, or care, what 2.6.32 might have done. It's too > outdated to be relevant. But the usbnet design is much older and > haven't changed drastically, so I assume most of the above is valid > there too. > > > Bjørn -- Narasimha _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
