| Message ID | 20211221101630.1146385-1-ewhac@ewhac.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] Input: spaceball - fix parsing of movement data packets | expand |
On Tue, Dec 21, 2021 at 02:16:31AM -0800, 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... > > Signed-off-by: Leo L. Schwab <ewhac@ewhac.org> Applied, thank you.
diff --git a/drivers/input/joystick/spaceball.c b/drivers/input/joystick/spaceball.c index 429411c6c0a8..10e09c86e067 100644 --- a/drivers/input/joystick/spaceball.c +++ b/drivers/input/joystick/spaceball.c @@ -19,6 +19,7 @@ #include <linux/module.h> #include <linux/input.h> #include <linux/serio.h> +#include <asm/unaligned.h> #define DRIVER_DESC "SpaceTec SpaceBall 2003/3003/4000 FLX driver" @@ -74,10 +75,16 @@ 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++) + data += 3; + for (i = 0; i < ARRAY_SIZE(spaceball_axes); ++i) { input_report_abs(dev, spaceball_axes[i], - (__s16)((data[2 * i + 3] << 8) | data[2 * i + 2])); + (__s16)get_unaligned_be16(&data[i * 2])); + } break; case 'K': /* Button data */
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... Signed-off-by: Leo L. Schwab <ewhac@ewhac.org> --- Changes in v2: - Coding style changes requested by <dmitry.torokhov@gmail.com>. drivers/input/joystick/spaceball.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)