Hello,

On 5/10/21 2:40 AM, Johan Hovold wrote:

On Thu, Apr 22, 2021 at 07:28:51PM -0500, Frank Zago wrote:

quoted

From: frank zago <frank@zago.net>

The 0x5512 USB PID is for the I2C/GPIO/SPI interfaces. UART is 
still present but only the TX and RX pins are available; DTS, DTR, 
... are used for other things. Remove the PID, and let a I2C
driver bind to it.

Existing CH341 boards usually have physical jumpers to switch 
between the 3 modes.

This reverts commit 46ee4abb10a07bd8f8ce910ee6b4ae6a947d7f63.

You can't just revert something which people clearly depend on and 
therefore added to the kernel in the first place.

That device in UART mode was already supported by the serial driver. The 
original submitter just had to move a jumper on his board. There was no 
need to patch the kernel.

That product ID also supports UART but in a limited way, as only the RX and TX
pins are available. However it is the only one that supports i2c/spi/gpio, and
that's why I have to revert the patch. 

If that's desired, the new driver could add support for that as well, but I don't
think it's worth the effort.

Can you reprogram the device with a newly allocated PID to be used 
for i2c-only instead?

It is possible if the device has an SPI flash connected to it, but none of
the cheap boards have that.

Frank.