• Frank Schäfer's avatar
    USB: pl2303: distinguish between original and cloned HX chips · 7d26a78f
    Frank Schäfer authored
    According to Prolific, several (unauthorized) cheap and less functional
    clones of the PL2303HX chip are in circulation. [1]
    I've had the chance to test such a cloned device and it turned out that
    it doesn't support any baud rates above 115200 baud (original: 6 Mbaud)
    It also doesn't support the divisior based baud rate encoding method,
    so no continuous baud rate adjustment is possible.
    Nevertheless, these devices have been working (unintentionally) with
    the driver up to commit 61fa8d69 ("pl2303: also use the divisor based
    baud rate encoding method for baud rates < 115200 with HX chips"), and
    this commit broke support for them.
    Fortunately, it is pretty simple to distinguish between the original
    and the cloned HX chips, so I've added a check and an extra chip type
    to keep the clones working.
    The same check is used by the latest Prolific Windows driver, so it
    should be solid.
    
    [1] http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=225&pcid=41Signed-off-by: default avatarFrank Schäfer <fschaefer.oss@googlemail.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    7d26a78f
pl2303.c 29 KB