Bug 217290

Summary:	issues with cdc ncm host class driver
Product:	Networking	Reporter:	Kaushal Purohit (kaushal.purohit)
Component:	Other	Assignee:	Stephen Hemminger (stephen)
Status:	RESOLVED CODE_FIX
Severity:	normal	CC:	kaushal.purohit, linux-usb, oliver, regressions
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	6.2.9	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	NCM capabilities description patch checking capability check for capability before filtering (improved)

Description Kaushal Purohit 2023-04-03 06:21:36 UTC

Created attachment 304078 [details]
NCM capabilities description

Hi,

Referring to patch with commit ID (e10dcb1b6ba714243ad5a35a11b91cc14103a9a9). 

This is a spec violation for CDC NCM class driver. Driver clearly says the significance of network capabilities. (snapshot attached)

https://www.usb.org/sites/default/files/NCM10_012011.zip (Spec)

However, with the mentioned patch these values are disrespected and commands specific to these capabilities are sent from the host regardless of device' capabilities to handle them.

Currently we are setting these bits to 0 indicating no capabilities on our device and still we observe that Host (Linux kernel host cdc driver) has been sending requests specific to these capabilities.

Please let me know if there is a better way to indicate host that device does not have these capabilities.

Thanks,
Kaushal

Comment 1 Oliver Neukum 2023-04-04 19:49:39 UTC

Created attachment 304084 [details]
patch checking capability

Comment 2 Oliver Neukum 2023-04-05 10:52:23 UTC

Created attachment 304086 [details]
check for capability before filtering (improved)

use symbolic constants for capability

Comment 3 The Linux kernel's regression tracker (Thorsten Leemhuis) 2023-05-22 09:21:25 UTC

This look stuck. 

Kaushal Purohit: did you ever try that patch? Or did you stop caring?

Comment 4 Kaushal Purohit 2023-06-27 06:46:30 UTC

Yes attached patch was working well. I did not see set filter params request after applying this patch.

Thanks for fixing it,
Kaushal