Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752296Ab0FWLP1 (ORCPT ); Wed, 23 Jun 2010 07:15:27 -0400 Received: from ch-smtp01.sth.basefarm.net ([80.76.149.212]:40818 "EHLO ch-smtp01.sth.basefarm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751217Ab0FWLP0 (ORCPT ); Wed, 23 Jun 2010 07:15:26 -0400 From: "Henrik Rydberg" To: Dmitry Torokhov Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Jiri Kosina , Ping Cheng , Benjamin Tissoires , Chase Douglas , Rafi Rubin , Henrik Rydberg Subject: [PATCH 2/5] input: Use driver hint to compute the evdev buffer size (rev3) Date: Wed, 23 Jun 2010 13:14:43 +0200 Message-Id: <1277291686-7153-3-git-send-email-rydberg@euromail.se> X-Mailer: git-send-email 1.6.3.3 In-Reply-To: <1277291686-7153-2-git-send-email-rydberg@euromail.se> References: <1277291686-7153-1-git-send-email-rydberg@euromail.se> <1277291686-7153-2-git-send-email-rydberg@euromail.se> X-Originating-IP: 83.248.196.134 X-Scan-Result: No virus found in message 1ORNv3-0007Mx-5J. X-Scan-Signature: ch-smtp01.sth.basefarm.net 1ORNv3-0007Mx-5J d3311891412231fabe1aa659c46ffe05 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2790 Lines: 79 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 | 17 +++++++++++++++++ 2 files changed, 21 insertions(+), 1 deletions(-) diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c index 5d84e59..728802f 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 @@ -51,7 +52,9 @@ static DEFINE_MUTEX(evdev_table_mutex); 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); } static void evdev_pass_event(struct evdev_client *client, diff --git a/include/linux/input.h b/include/linux/input.h index 20e4eac..9e024b6 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 +1441,21 @@ 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); +/** + * input_set_events_per_packet - tell handlers about the driver event rate + * @dev: the input device used by the driver + * @nev: 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 approriate 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 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/