From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Henrik Rydberg" Subject: [PATCH 3/3] input: use driver hint to compute the evdev buffer size Date: Sat, 29 May 2010 17:57:44 +0200 Message-ID: <1275148664-6238-4-git-send-email-rydberg@euromail.se> References: <1275148664-6238-1-git-send-email-rydberg@euromail.se> <1275148664-6238-2-git-send-email-rydberg@euromail.se> <1275148664-6238-3-git-send-email-rydberg@euromail.se> Return-path: Received: from ch-smtp03.sth.basefarm.net ([80.76.149.214]:51301 "EHLO ch-smtp03.sth.basefarm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757544Ab0E2P6y (ORCPT ); Sat, 29 May 2010 11:58:54 -0400 In-Reply-To: <1275148664-6238-3-git-send-email-rydberg@euromail.se> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Dmitry Torokhov Cc: linux-input@vger.kernel.org, Jiri Kosina , Mika Kuoppala , Benjamin Tissoires , Rafi Rubin , Henrik Rydberg Some devices, in particular MT devices, produce a lot of data. This leads to a high frequency of lost packets in evdev, which by default uses a fairly small event buffer. Let the drivers hint the average number of events per packet for the device by calling the input_set_events_per_packet(), and use that information when computing the evdev buffer size. Signed-off-by: Henrik Rydberg --- drivers/input/evdev.c | 5 ++++- include/linux/input.h | 7 +++++++ 2 files changed, 11 insertions(+), 1 deletions(-) diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c index 327f821..fdddb43 100644 --- a/drivers/input/evdev.c +++ b/drivers/input/evdev.c @@ -11,6 +11,7 @@ #define EVDEV_MINOR_BASE 64 #define EVDEV_MINORS 32 #define EVDEV_MIN_BUFFER_SIZE 64 +#define EVDEV_BUF_PACKETS 8 #include #include @@ -807,7 +808,9 @@ static void evdev_cleanup(struct evdev *evdev) static int evdev_compute_buffer_size(struct input_dev *dev) { - return EVDEV_MIN_BUFFER_SIZE; + int nev = dev->hint_events_per_packet * EVDEV_BUF_PACKETS; + nev = max(nev, EVDEV_MIN_BUFFER_SIZE); + return roundup_pow_of_two(nev); } /* diff --git a/include/linux/input.h b/include/linux/input.h index bd00786..35b015d 100644 --- a/include/linux/input.h +++ b/include/linux/input.h @@ -1162,6 +1162,8 @@ 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; @@ -1439,6 +1441,11 @@ static inline void input_mt_slot(struct input_dev *dev, int slot) void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int code); +static inline void input_set_events_per_packet(struct input_dev *dev, int nev) +{ + dev->hint_events_per_packet = nev; +} + 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; -- 1.6.3.3