Hi Michel, and sorry about the late feedback on this one. On Tue, Mar 31, 2020 at 11:37:16PM +0000, Michael Hanselmann wrote: > 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 Good summary, and generally clean overall. I know you replied to my earlier comments mentioning what you had done for v2, but its good always include a short changelog here when resending a series. > 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(-) Johan
