Number of NTB buffers configuration option (IEC-251)

[ctag-fh-kiel]

Is your feature request related to a problem?

With the current NTB buffer settings, USB-NCM does not seem to work properly and does not achieve optimal performance.
In my setup the following error occurs quite frequently:
tud_network_can_xmit: request blocked

Describe the solution you'd like.

Add configuration option for CFG_TUD_NCM_OUT_NTB_N and CFG_TUD_NCM_IN_NTB_N via component config.
I.e. enhancing tusb_config.h of the component with:
#define CFG_TUD_NCM_IN_NTB_N CONFIG_TINYUSB_NCM_IN_NTB_N
#define CFG_TUD_NCM_OUT_NTB_N CONFIG_TINYUSB_NCM_OUT_NTB_N

and adding to KConfig relevant lines to configure it.

Describe alternatives you've considered.

No response

Additional context.

No response

[peter-marcisovsky]

Hi @ctag-fh-kiel
Thanks for the report, we will take a look.

Could you please specify which chip and which version of Tinyusb are you using?
In the meanwhile, could you please take a look a the #107 and see if the issue is relevant to yours?

[ctag-fh-kiel]

#107 may be relevant, I posted this in the relevant thread.
I am using esp32-s3 and the Tinyusb version bundled with
espressif/esp_tinyusb:
version: "^1.6.0"

[peter-marcisovsky]

Thank's for the info. I can observe the same behavior.

I presume, you did try to change CFG_TUD_NCM_IN_NTB_N and CFG_TUD_NCM_OUT_NTB_N settings, If yes, how many buffers did you have to use to stop seeing the (II) tud_network_can_xmit: request blocked ?

In the TInyUSB ncm.h it's stated that, for RPi RP2040, the CFG_TUD_NCM_IN_NTB_N shall be set to 3, to mitigate the (II) tud_network_can_xmit: request blocked warning

I biriefly ran iperf with both buffer counts set to 2 and the warning message was not preset anymore.
But, on the other hand, I used esp32s3 as NCM Network Adapter for my Laptop and I had to set the buffer count very high to mitigate the warning (but I was browsing google maps to induce a higher traffic, which is bit extreme case).

[ctag-fh-kiel]

I have set
CFG_TUD_NCM_IN_NTB_N=3
CFG_TUD_NCM_OUT_NTB_N=2
as per recommendation in ncm.h