Callback to set default link state?

[morse-cedricvandenbergh]

Hi,

What would be the best way to set ncm_interface.link_is_up in netd_init, if the link state could be either up or down?

I have noted that if the host reboots, the USB device isn;t alwasys powered down, which in turn means the phycial link state remains the same befoire as after the reboot. However, because netd_init resets the ncm_interface.link_is_up state to CFG_TUD_NCM_DEFAULT_LINK_UP (down in our case), tinyUSB will report the link state as down.

I wonder what the suggested mechanism to fix this would be. I see a number of options.

• Use a weak callback into the application to set the value in netd_init
• Change the CFG_TUD_NCM_DEFAULT_LINK_UP macro to call a function (feels like a hack)
• Have the application call tud_network_link_state at some other USB event (tud_mount_cb perhaps?)

I have implemented the first option and that appears to work well on both Ubuntu (24.04 on a Dell Latitude laptop) and Windows (on a dell XPS).

[HiFiPhile]

I prefer a weak callback with default value set to CFG_TUD_NCM_DEFAULT_LINK_UP

[morse-cedricvandenbergh]

Ok. Thanks.

Having tested in more detail (and checked the logs), I am starting to think that simply calling tud_network_link_state() from tud_mount_cb() should be sufficient. Our implementation has an unrelated issue which was adding to my confusion.

If it turns out more is needed, I'll go with the weak callback approach.

Thanks again for the quick advice

Cedric

[morse-cedricvandenbergh]

Eventually implemented the weak call back after all.