kernel.git/drivers/usb/serial/ch341.c, branch linux-5.8.y

USB: serial: ch341: add new Product ID for CH340

2020-06-23T08:57:27Z

Add PID for CH340 that's found on some ESP8266 dev boards made by LilyGO. The specific device that contains such serial converter can be seen here: https://github.com/LilyGO/LILYGO-T-OI. Apparently, it's a regular CH340, but I've confirmed with others that also bought this board that the PID found on this device (0x7522) differs from other devices with the "same" converter (0x7523). Simply adding its PID to the driver and rebuilding it made it work as expected. Signed-off-by: Igor Moura Cc: stable@vger.kernel.org Signed-off-by: Johan Hovold

USB: serial: ch341: fix lockup of devices with limited prescaler

2020-05-27T13:01:05Z

Michael Hanselmann reports that [a] subset of all CH341 devices stop responding to bulk transfers, usually after the third byte, when the highest prescaler bit (0b100) is set. There is one exception, namely a prescaler of exactly 0b111 (fact=1, ps=3). Fix this by forcing a lower base clock (fact = 0) whenever needed. This specifically makes the standard rates 110, 134 and 200 bps work again with these devices. Fixes: 35714565089e ("USB: serial: ch341: reimplement line-speed handling") Cc: stable # 5.5 Reported-by: Michael Hanselmann Link: https://lore.kernel.org/r/20200514141743.GE25962@localhost Signed-off-by: Johan Hovold

USB: serial: ch341: add basis for quirk detection

2020-05-27T13:00:56Z

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. This patch adds a detection function which will be extended to set quirk flags as they're implemented. The author's affected device has an imprint of "340" on the turquoise-colored plug, but not all such devices appear to be affected. Signed-off-by: Michael Hanselmann Link: https://lore.kernel.org/r/1e1ae0da6082bb528a44ef323d4e1d3733d38858.1585697281.git.public@hansmi.ch [ johan: use long type for quirks; rephrase and use port device for messages; handle short reads; set quirk flags directly in helper function ] Cc: stable # 5.5 Signed-off-by: Johan Hovold

USB: serial: ch341: fix receiver regression

2020-02-10T09:10:35Z

While assumed not to make a difference, not using the factor-2 prescaler makes the receiver more susceptible to errors. Specifically, there have been reports of problems with devices that cannot generate a 115200 rate with a smaller error than 2.1% (e.g. 117647 bps). But this can also be reproduced with a low-speed RS232 tranceiver at 115200 when the input rate matches the nominal rate. So whenever possible, enable the factor-2 prescaler and halve the divisor in order to use settings closer to that of the previous algorithm. Fixes: 35714565089e ("USB: serial: ch341: reimplement line-speed handling") Cc: stable # 5.5 Reported-by: Jakub Nantl Tested-by: Jakub Nantl Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold

USB: serial: ch341: handle unbound port at reset_resume

2020-01-17T15:22:45Z

Check for NULL port data in reset_resume() to avoid dereferencing a NULL pointer in case the port device isn't bound to a driver (e.g. after a failed control request at port probe). Fixes: 1ded7ea47b88 ("USB: ch341 serial: fix port number changed after resume") Cc: stable # 2.6.30 Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold

USB: serial: ch341: reimplement line-speed handling

2019-11-04T11:49:51Z

The current ch341 divisor algorithm was known to give inaccurate results for certain higher line speeds. Jonathan Olds investigated this, determined the basic equations used to derive the divisors and confirmed them experimentally [1]. The equations Jonathan used could be generalised further to: baudrate = 48000000 / (2^(12 - 3 * ps - fact) * div), where 0 <= ps <= 3, 0 <= fact <= 1, 2 <= div <= 256 if fact = 0, or 9 <= div <= 256 if fact = 1 which will also give better results for lower rates. Notably the error is reduced for the following standard rates: 1152000 (4.0% instead of 15% error) 921600 (0.16% instead of -7.5% error) 576000 (-0.80% instead of -5.6% error) 200 (0.16% instead of -0.69% error) 134 (-0.05% instead of -0.63% error) 110 (0.03% instead of -0.44% error) but also for many non-standard ones. The current algorithm also suffered from rounding issues (e.g. requesting 2950000 Bd resulted in a rate of 2 MBd instead of 3 MBd and thus a -32% instead of 1.7% error). The new algorithm was inspired by the current vendor driver even if that one only handles two higher rates that require fact=1 by hard coding the corresponding divisors [2]. Michael Dreher also did a similar generalisation of Jonathan's work and has published his results with a very good summary that provides further insights into how this device works [3]. [1] https://lkml.kernel.org/r/000001d51f34$bad6afd0$30840f70$@co.nz [2] http://www.wch.cn/download/CH341SER_LINUX_ZIP.html [3] https://github.com/nospam2000/ch341-baudrate-calculation Reported-by: Jonathan Olds Tested-by: Jonathan Olds Cc: Michael Dreher Signed-off-by: Johan Hovold

USB: serial: ch341: fix type promotion bug in ch341_control_in()

2018-07-04T13:40:54Z

The "r" variable is an int and "bufsize" is an unsigned int so the comparison is type promoted to unsigned. If usb_control_msg() returns a negative that is treated as a high positive value and the error handling doesn't work. Fixes: 2d5a9c72d0c4 ("USB: serial: ch341: fix control-message error handling") Signed-off-by: Dan Carpenter Cc: stable Signed-off-by: Johan Hovold

USB: serial: fix module-license macros

2017-11-04T10:58:00Z

Several GPL-2.0 drivers used "GPL" rather than "GPL v2" in their MODULE_LICENSE macros; fix the macros to match the licenses. Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: serial: Remove redundant license text

2017-11-04T10:55:38Z

Now that the SPDX tag is in all USB files, that identifies the license in a specific and legally-defined manner. So the extra GPL text wording can be removed as it is no longer needed at all. This is done on a quest to remove the 700+ different ways that files in the kernel describe the GPL license text. And there's unneeded stuff like the address (sometimes incorrect) for the FSF which is never needed. No copyright headers or other non-license-description text was removed. Signed-off-by: Greg Kroah-Hartman Acked-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: add SPDX identifiers to all remaining files in drivers/usb/

2017-11-04T10:48:02Z

It's good to have SPDX identifiers in all files to make it easier to audit the kernel tree for correct licenses. Update the drivers/usb/ and include/linux/usb* files with the correct SPDX license identifier based on the license text in the file itself. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This work is based on a script and data from Thomas Gleixner, Philippe Ombredanne, and Kate Stewart. Cc: Thomas Gleixner Cc: Kate Stewart Cc: Philippe Ombredanne Signed-off-by: Greg Kroah-Hartman Acked-by: Felipe Balbi Acked-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman