Re: USB cdc-acm driver: break and command

[Greg KH]

On Tue, Jul 15, 2025 at 02:00:10PM -0700, H. Peter Anvin wrote:
> Hi,
> 
> I noticed looking at the CDC-ACM driver that it uses the assert/local
> delay/deassert method of sending BREAK.  Given that the CDC model has a
> delay specifier in the command packet, is there any reason not to set
> TTY_DRIVER_HARDWARE_BREAK and sending only one packet?
> 
> I'm also wondering if it would make sense to support the
> SEND_ENCAPSULATED_COMMAND and GET_ENCAPSULATED_RESPONSE commands, presumably
> via an ioctl().  I'm not 100% sure because I'm not sure there aren't
> potential security issues.
> 
> I'm guessing both of these could be of some use to embedded devices that
> emulate a ttyACM serial port.

No idea why this is that way, sorry.  Try making the change and see if
it actually works?

thanks,

greg k-h