From: Michael Hanselmann <public@hansmi.ch>
To: linux-usb@vger.kernel.org, Johan Hovold <johan@kernel.org>
Cc: Michael Hanselmann <public@hansmi.ch>,
Michael Dreher <michael@5dot1.de>,
Jonathan Olds <jontio@i4free.co.nz>
Subject: [PATCH v2 0/6] USB: serial: ch341: Add support for limited chips (was: Add support for HL340 devices)
Date: Tue, 31 Mar 2020 23:37:16 +0000 [thread overview]
Message-ID: <cover.1585697281.git.public@hansmi.ch> (raw)
A subset of CH341 devices does not support all features, namely the
prescaler is limited to a reduced precision and there is no support for
sending a RS232 break condition.
These devices can usually be identified by an imprint of "340" on the
turquoise-colored plug. They're also sometimes called "HL340", but not
all such devices are affected.
This series takes multiple steps to support the limited chips:
* Remove special cases from clock prescaler computation
* Detect limited devices by trying to read a register related to sending
a break condition
* Amend clock prescaler computation to only use working values on
limited chips
* Simulate an RS232 break condition by temporarily lowering the baud
rate and sending a NUL byte
Michael Hanselmann (6):
USB: serial: ch341: Reduce special cases in clock calculation
USB: serial: ch341: Add basis for quirk detection
USB: serial: ch341: Limit prescaler on quirky chips
USB: serial: ch341: Name prescaler, divisor registers
USB: serial: ch341: Compute minimum baud rate
USB: serial: ch341: Simulate break condition if not supported
drivers/usb/serial/ch341.c | 294 ++++++++++++++++++++++++++++++-------
1 file changed, 244 insertions(+), 50 deletions(-)
--
2.20.1
next reply other threads:[~2020-03-31 23:37 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-31 23:37 Michael Hanselmann [this message]
2020-03-31 23:37 ` [PATCH v2 1/6] USB: serial: ch341: Reduce special cases in clock calculation Michael Hanselmann
2020-03-31 23:37 ` [PATCH v2 2/6] USB: serial: ch341: Add basis for quirk detection Michael Hanselmann
2020-05-14 14:09 ` Johan Hovold
2020-03-31 23:37 ` [PATCH v2 3/6] USB: serial: ch341: Limit prescaler on quirky chips Michael Hanselmann
2020-05-14 14:17 ` Johan Hovold
2020-05-27 13:16 ` Johan Hovold
2020-05-27 15:41 ` Michael Hanselmann
2020-05-29 7:15 ` Johan Hovold
2020-03-31 23:37 ` [PATCH v2 4/6] USB: serial: ch341: Name prescaler, divisor registers Michael Hanselmann
2020-05-14 14:24 ` Johan Hovold
2020-05-27 20:59 ` Michael Hanselmann
2020-06-29 9:51 ` Johan Hovold
2020-03-31 23:37 ` [PATCH v2 5/6] USB: serial: ch341: Compute minimum baud rate Michael Hanselmann
2020-05-27 22:19 ` Michael Hanselmann
2020-06-30 9:57 ` Johan Hovold
2020-03-31 23:37 ` [PATCH v2 6/6] USB: serial: ch341: Simulate break condition if not supported Michael Hanselmann
2020-05-14 14:47 ` Johan Hovold
2020-05-27 22:21 ` Michael Hanselmann
2020-06-30 11:39 ` Johan Hovold
2020-07-04 18:25 ` Michael Hanselmann
2020-07-06 9:31 ` Johan Hovold
2020-05-14 14:02 ` [PATCH v2 0/6] USB: serial: ch341: Add support for limited chips (was: Add support for HL340 devices) Johan Hovold
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