Hi Leo, On Mon, Jul 26, 2021 at 09:06:24PM -0700, Leo L. Schwab wrote: > The spaceball.c module was not properly parsing the movement reports > coming from the device. The code read axis data as signed 16-bit > little-endian values starting at offset 2. > > In fact, axis data in Spaceball movement reports are signed 16-bit > big-endian values starting at offset 3. This was determined first by > visually inspecting the data packets, and later verified by consulting: > http://spacemice.org/pdf/SpaceBall_2003-3003_Protocol.pdf > > If this ever worked properly, it was in the time before Git... Thank you for the patch. > > Signed-off-by: Leo L. Schwab <ewhac@xxxxxxxxx> > --- > drivers/input/joystick/spaceball.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/drivers/input/joystick/spaceball.c b/drivers/input/joystick/spaceball.c > index 429411c6c0a8..43bfb3d2fa8a 100644 > --- a/drivers/input/joystick/spaceball.c > +++ b/drivers/input/joystick/spaceball.c > @@ -74,10 +74,20 @@ static void spaceball_process_packet(struct spaceball* spaceball) > switch (spaceball->data[0]) { > > case 'D': /* Ball data */ > + /* > + * Skip first three bytes; read six axes worth of data. > + * Axis values are signed 16-bit big-endian. > + */ > if (spaceball->idx != 15) return; > - for (i = 0; i < 6; i++) > - input_report_abs(dev, spaceball_axes[i], > - (__s16)((data[2 * i + 3] << 8) | data[2 * i + 2])); > + data += 3; > + for (i = 0; > + i < ARRAY_SIZE(spaceball_axes); > + ++i, data += sizeof(__s16)) { > + input_report_abs( > + dev, > + spaceball_axes[i], > + (__s16)((data[0] << 8) | data[1])); > + } Could we write for (i == 0; i < ARRAY_SIZE(spaceball_axes); i++) input_report_abs(dev, spaceball_axes[i], (__s16)(get_unaligned_be16(&data[i * 2]); instead? Thanks! -- Dmitry
