diff options
| author | Leo L. Schwab <ewhac@ewhac.org> | 2021-12-30 21:05:00 -0800 |
|---|---|---|
| committer | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2021-12-30 21:09:29 -0800 |
| commit | bc7ec91718c49d938849697cfad98fcd9877cc26 (patch) | |
| tree | bceeff1678637822caf77d00c30f752535dfb710 | |
| parent | 9f3ccdc3f6ef10084ceb3a47df0961bec6196fd0 (diff) | |
Input: spaceball - fix parsing of movement data packets
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>
Link: https://lore.kernel.org/r/20211221101630.1146385-1-ewhac@ewhac.org
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
| -rw-r--r-- | drivers/input/joystick/spaceball.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/input/joystick/spaceball.c b/drivers/input/joystick/spaceball.c index 429411c6c0a8..a85a4f33aea8 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" @@ -75,9 +76,15 @@ static void spaceball_process_packet(struct spaceball* spaceball) case 'D': /* Ball data */ if (spaceball->idx != 15) return; - for (i = 0; i < 6; i++) + /* + * Skip first three bytes; read six axes worth of data. + * Axis values are signed 16-bit big-endian. + */ + 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 */ |