diff options
| -rw-r--r-- | drivers/input/evdev.c | 9 | ||||
| -rw-r--r-- | include/linux/input.h | 21 |
2 files changed, 28 insertions, 2 deletions
diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c index cff7bf9351a8..30836c05edd7 100644 --- a/drivers/input/evdev.c +++ b/drivers/input/evdev.c @@ -10,7 +10,8 @@ #define EVDEV_MINOR_BASE 64 #define EVDEV_MINORS 32 -#define EVDEV_MIN_BUFFER_SIZE 64 +#define EVDEV_MIN_BUFFER_SIZE 64U +#define EVDEV_BUF_PACKETS 8 #include <linux/poll.h> #include <linux/sched.h> @@ -245,7 +246,11 @@ static int evdev_release(struct inode *inode, struct file *file) static unsigned int evdev_compute_buffer_size(struct input_dev *dev) { - return EVDEV_MIN_BUFFER_SIZE; + unsigned int n_events = + max(dev->hint_events_per_packet * EVDEV_BUF_PACKETS, + EVDEV_MIN_BUFFER_SIZE); + + return roundup_pow_of_two(n_events); } static int evdev_open(struct inode *inode, struct file *file) diff --git a/include/linux/input.h b/include/linux/input.h index 6fcc9101beeb..cc524c8b6703 100644 --- a/include/linux/input.h +++ b/include/linux/input.h @@ -1063,6 +1063,10 @@ struct ff_effect { * @sndbit: bitmap of sound effects supported by the device * @ffbit: bitmap of force feedback effects supported by the device * @swbit: bitmap of switches present on the device + * @hint_events_per_packet: average number of events generated by the + * device in a packet (between EV_SYN/SYN_REPORT events). Used by + * event handlers to estimate size of the buffer needed to hold + * events. * @keycodemax: size of keycode table * @keycodesize: size of elements in keycode table * @keycode: map of scancodes to keycodes for this device @@ -1140,6 +1144,8 @@ struct input_dev { unsigned long ffbit[BITS_TO_LONGS(FF_CNT)]; unsigned long swbit[BITS_TO_LONGS(SW_CNT)]; + unsigned int hint_events_per_packet; + unsigned int keycodemax; unsigned int keycodesize; void *keycode; @@ -1408,6 +1414,21 @@ static inline void input_mt_sync(struct input_dev *dev) void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int code); +/** + * input_set_events_per_packet - tell handlers about the driver event rate + * @dev: the input device used by the driver + * @n_events: the average number of events between calls to input_sync() + * + * If the event rate sent from a device is unusually large, use this + * function to set the expected event rate. This will allow handlers + * to set up an appropriate buffer size for the event stream, in order + * to minimize information loss. + */ +static inline void input_set_events_per_packet(struct input_dev *dev, int n_events) +{ + dev->hint_events_per_packet = n_events; +} + static inline void input_set_abs_params(struct input_dev *dev, int axis, int min, int max, int fuzz, int flat) { dev->absmin[axis] = min; |