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From: "H. Peter Anvin" <hpa@zytor.com>
To: Oliver Neukum <oneukum@suse.com>
Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	gregkh@linuxfoundation.org, Jiri Slaby <jirislaby@kernel.org>,
	linux-serial@vger.kernel.org
Subject: USB cdc-acm driver: break and command
Date: Tue, 15 Jul 2025 14:00:10 -0700	[thread overview]
Message-ID: <ce54ae11-72bb-4ac7-980b-c1cbc798a209@zytor.com> (raw)

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.

	-hpa


             reply	other threads:[~2025-07-15 21:00 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-15 21:00 H. Peter Anvin [this message]
2025-07-16  6:58 ` Greg KH
2025-07-16  8:29 ` Oliver Neukum
2025-07-16 15:06   ` H. Peter Anvin
2025-07-16 16:17     ` Oliver Neukum
2025-07-16 17:30       ` H. Peter Anvin
2025-07-17 11:32         ` Oliver Neukum
2025-07-16 17:49       ` H. Peter Anvin
2025-07-17 11:28         ` Oliver Neukum

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